Saturday, April 9, 2011
8th Grade-Unit7-Physical/Chemical Changes
 8th Grade Science Physical and Chemical ChangesIndicators and Objectives for this Unit 4. 7. D. Physical and Chemical Changes 1. Cite evidence to support the fact that some substances can be separated into the original substances from which they were made.  components. · Magnetism · Boiling Point · Solubility in water b. Based on data gathered, identify and describe various processes used to separate mixtures. · Filtration · Evaporation · Paper Chromatography 4. 8. D. Physical and Chemical Changes 2. Cite evidence and give examples of chemical properties of substances. a. Based on data from investigations and research, identify and describe chemical properties of common substances. · Reacts with oxygen (rusting/tarnishing and burning · Reacts with acids (dissolves metal) · Reacts with bases (forms soap) b. Use information gathered from investigations using indicators and the pH scale to classify materials as acidic, basic, or neutral. 4. 8. D. Physical and Chemical changes 3. Provide evidence to support the fact that common substances have the ability to change into new substances. a. Investigate and describe the occurrence of chemical reactions using the following evidence: · Color change · Formation of a precipitate or gas · Release of heat or light e. Provide examples to explain the difference between a physical change and a chemical change. Matter can be identified through its properties. Properties of matter can be physical or chemical. |
§ Changes in matter can be described in terms of physical changes and chemical changes.
§ Energy can cause physical changes in matter. It is needed to change the volume, temperature or pressure of matter.
§ A chemical change involves making and breaking chemical bonds to form a new substance. Chemical changes can either absorb or release energy. In chemical reactions molecules break apart, rearrange, and join together to form different substances.
§ A mixture is a substance made by combining two or more different materials with no chemical reaction occurring. It is a combination of two or more substances that are not chemically united and do not exist in fixed proportions to each other. It can be physically separated into pure compounds or elements. Most natural substances are mixtures.
§ Characteristic properties can be used to separate a mixture.
Physical property
Chemical property
Extensive/extrinsic property
Intensive/intrinsic property
Boiling point
Freezing point
Melting point
Solubility
Mixture
Homogeneous mixture
Heterogeneous mixture
Solution
Solute
Solvent
Soluble insoluble
Vaporization
Condensation
Evaporation
Filtration
Magnetism
Paper chromatography
Chemical change/chemical reaction
Physical change
Chemical equation
Reactants
Products
Combustion
Acids
Bases
Salts
Neutral
Indicator
ph scale
ph meter
Temperature
Thermal energy
Thermal expansion
§ Physical properties of matter: The characteristics of matter that can be observed without causing.
§ Mass: Mass is the quantity of matter contained in a body.
§ Density: It is the mass of a substance per unit volume.
§ Elasticity: It is the ability of a substance to return to its original shape and size after being bent, stretched or compressed. Ex. Rubber band, spring balance.
§ Hardness: The ability to any change to the matter are collectively called its physical properties. E.g. color, size, shape, density, hardness, strength, flexibility, electrical conductivity, thermal conductivity, boiling point, melting point etc. are all physical propertieswithstand wear and tear and scratches. Ex. Diamond
§ Strength: The ability to support heavy load without tearing and breaking. Ex. Steel
§ Solubility: It is the maximum quantity of the solute which can be dissolved in a given quantity of solvent. For example 30g of sugar is soluble in 100 cubic cm of water.
§ Melting point: It is the temperature at which a substance changes from solid to liquid states. Ex. Ice changes to water at 0 degree Celsius.
§ Boiling point: It is the temperature at which a substance changes from liquid to vapor state. Ex. Water changes to water vapor at 100 degree Celsius.
§ Electrical conductivity: It is the measure of readiness for electricity to flow through a substance. Ex. Wood, rubber etc are poor conductors of electricity.
§ Thermal conductivity: The readiness of a substance to allow heat to flow through. Metals are good conductors of heat. So we use them for cooking.
§ Flexibility: The extent to which the substance changes its shape without breaking even when force is applied on it. Aluminum and many plastic are flexible substances.
§ Transparency: It is the ability of a substance to allow light to pass through it. Glass and some plastic films are more transparent than brick or wood.
§ Viscosity: It can be described as the ease with which a fluid flows. Higher the viscosity, less easy is the flow. Oil is more viscous than water. (Oil flows slower than water.)
Assignment=Please copy this into your journal and answer the questions there
PRE TEST
|
| ||||
|
| ||||
|
| ||||
|
| ||||
|
Size and shape
State of matter
Appearance
All of the abovePRETEST
|
| ||||
|
| ||||
|
| ||||
|
|
| 8th grade chemistry |
 |
| 1. | Chemical weathering occurs when rain mixes with (acids, Filtration, Thermal expansion) in rocks. | |
| 2. | The (Combustion, Acids, magnetism) between the magnet and the paper clip was strong. | |
| 3. | Acids and bases are (Thermal energy, reactants, Filtration) . | |
| 4. | Acids and (Thermal energy, bases, Acids) are reactants. | |
| 5. | (Indicator, Acids, Physical change) and bases are reactants. | |
| 6. | The products of a (Magnetism, combustion, Physical change) reaction are carbon dioxide and water vapor. | |
| 7. | (Salts, Magnetism, Filtration) keeps kitchen magnets attached to a refrigerator door. | |
| 8. | The (indicator, Filtration, Thermal energy) showed that the pH was very acidic. | |
| 9. | Generic brands are considered inferior to brand named (Physical change, ph scale, products) . | |
| 10. | When a substance bursts into flames by itself, we say that the process of spontaneous (Acids, combustion, Reactants) has occurred. | |
| 11. | In (filtration, Acids, Indicator) , dirty water is passed through layers of sand and gravel. | |
| 12. | The mystery box showed no (Physical change, Chemical change, magnetism) when the student checked it for magna etic objects. | |
| 13. | Household cleaning (products, Chemical change, Magnetism) can be dangerous since they are flammable. |
| How Matter Changes By Cindy Grigg | |
1 Changes in matter happen around you every day. Some changes make matter look different. Other changes make one kind of matter become another kind of matter.2 When you scrunch a sheet of paper up into a ball, it is still paper. It only changed shape. You can cut a large, rectangular piece of paper into many small triangles. It changed shape and size, but it is still paper. These kinds of changes are called physical changes.
3 Physical changes are changes in the way matter looks. Changes in size and shape, like the changes in the cut pieces of paper, are physical changes. Physical changes are changes in the size, shape, state, or appearance of matter.
4 Another kind of physical change happens when matter changes from one state to another state. When water freezes and makes ice, it is still water. It has only changed its state of matter from a liquid to a solid. It has changed its appearance and shape, but it is still water. You can change the ice back into water by letting it melt. Matter looks different when it changes states, but it stays the same kind of matter.
5 Solids like ice can change into liquids. Heat speeds up the moving particles in ice. The particles move apart. Heat melts ice and changes it to liquid water. Metals can be changed from a solid to a liquid state also. Metals must be heated to a high temperature to melt. Melting is changing from a solid state to a liquid state.
6 Ice melts at 0 degrees Celsius or 32 degrees Fahrenheit. This is the melting point (or freezing point) of water. If the temperature goes above this temperature, the ice will melt. Heat speeds up the moving particles in ice. If the temperature goes below this temperature, water will freeze. At colder temperatures, the moving particles slow down.
7 You have probably seen a puddle of water that disappears after a time. The water in the puddle changed into a gas. Matter evaporates when it changes from a liquid to a gas. Water in the form of gas is called water vapor.
8 Water changes quickly into a gas when water is heated to a temperature of 100 degrees Celsius or 212 degrees Fahrenheit. This temperature is the boiling point of water. Heat makes water particles move fast.
9 Cooling air causes water vapor to change to a liquid. Matter condenses when it changes from a gas to a liquid.
10 Have you ever had a glass of lemonade with ice on a hot summer day? Did you notice the water that beaded up on the outside of the glass? The cold glass cooled the air around it. Then water vapor in the air condensed to small drops of water on the outside of the glass.
Assignment=Please copy this "Main idea and Details" graphic organizer into your journal and answer the questions there from the reading above.
11 Another way matter can change is a chemical change. A chemical change takes place when matter changes into a different kind of matter. An example of a chemical change is burning wood. The wood changes into smoke and ash. This chemical change produces heat and light.
12 Have you ever seen a nail or other piece of metal that was rusted? Rusting is a chemical change, too. The metal in the nails mixes with the air to form a different kind of matter, rust.
13 Have you ever seen an old piece of silverware that has turned black? This is another kind of chemical change. A gas in the air causes a black covering called tarnish to form on silver. The tarnish is a different kind of matter from the air or the silver.
Assignment=Please copy this "Main idea and Details" graphic organizer into your journal and answer the questions there from the reading above.
14 Signs of a chemical change are a change in color or temperature or the production of heat or light. Bubbling, fizzing, or making a noise or smell are some more signs. Not all of these things happen during a chemical change. But usually at least one of them does happen.
15 Changes in the way matter looks are physical changes. A physical change happens when matter changes from one state into another. A chemical change takes place when matter changes to a different kind of matter.Assignment=Please copy this "Main idea and Details" graphic organizer into your journal and answer the questions there from the reading above.
Copyright © 2011 edHelper
|
| ||||
|
| ||||
|
| ||||
|
| ||||
|
Assignment=Please watch this video @ Matter and It's Changes and take between 15-20 notes about it's main ideas and facts
How Matter Changes
| __ |
Assignment=Please copy in journal and complete each sentence there
| 14. | There were no perceptible differences between the two (Salts, Reactants, products) . | |
| 15. | The paperclip showed no (Filtration, magnetism, Salts) . | |
| 16. | Oxygen is a necessary reactant in any (Indicator, Physical change, combustion) reaction. | |
| 17. | The magnetic field is the space around a magnet where (ph scale, magnetism, Acids) acts. | |
| 18. | Red and blue litmus paper chan be used as an (Bases, indicator, ph scale) to detect the presence of an acid or a base in a solution. | |
| 19. | Through the process of (Magnetism, filtration, Products) , water treatment plants can clean water. | |
| 20. | The (Products, combustion, Filtration) engine is respondible for propelling forward cars and rockets. | |
| 21. | The plant manufactures steel (Thermal energy, products, ph scale) . | |
| 22. | The power made by the (combustion, ph scale, Magnetism) was enough to power the car. | |
| 23. | Wide range pH paper can be used as an (Products, indicator, Salts) to determine the strength of an acid or a base in a solution. | |
| 24. | (Magnetism, Bases, Reactants) pulls metal objects together. | |
| 25. | (Magnetism, Thermal expansion, Ph scale) is the force by which objects are attracted to other objects or repelled by other objects. | |
| 26. | we have been studying (magnetism, Filtration, Reactants) . |
Assignment=Please watch this video @chemical reactions and take between 15-20 notes about it's main ideas and facts
Assignment=Please copy this into your journal and answer the questions there
| How Matter Changes By Cindy Grigg | |
Directions: Fill in each blank with the word that best completes the reading comprehension.
Changes in matter happen around you every day. Some changes make matter look different. Other changes make one kind of matter(1) _______________________ another kind of matter.When you scrunch a sheet of paper up into a ball, it is still paper. It only changed shape. You can cut a (2) _______________________ , rectangular piece of paper into many small triangles. It changed shape and size, but it is still paper. These kinds of changes are called physical changes.
Physical changes are changes in the way matter looks. Changes in size and shape, like the changes in the cut pieces of paper, are physical changes. Physical changes are changes in the size, shape, (3) _______________________ , or appearance of matter.
Another kind of physical change happens when matter changes from one state to another state. When water freezes and makes ice, it is still water. It has only changed its state of matter from a liquid to a solid. It has changed its appearance and shape, but it is still water. You can change the ice back into water by letting it melt. Matter looks different when it changes(4) _______________________ , but it stays the same kind of matter.
Solids like ice can change into liquids. Heat speeds up the moving particles in ice. The particles move apart.(5) _______________________ melts ice and changes it to liquid water. Metals can be changed from a solid to a liquid state(6) _______________________ . Metals must be heated to a high temperature to melt. Melting is changing from a solid state to a liquid state.
Ice melts at 0 degrees Celsius or 32 degrees Fahrenheit. This is the melting (7) _______________________ (or freezing point) of water. If the temperature goes above this temperature, the ice will melt. Heat speeds up the moving particles in ice. If the temperature goes below this temperature, water will freeze. At colder temperatures, the moving particles slow down.
You have probably seen a puddle of water that disappears after a time. The water in the puddle changed into a gas. Matterevaporates when it changes from a liquid to a gas. Water in the form of gas is called water vapor.
Water changes quickly into a gas when water is (8) _______________________ to a temperature of 100 degrees Celsius or 212 degrees Fahrenheit. This temperature is the (9) _______________________ point of water. Heat makes water particles move fast.
Cooling air causes water vapor to change to a liquid. Matter condenses when it changes from a gas to a liquid.
Have you ever had a glass of lemonade with ice on a hot summer day? Did you notice the water that beaded up on the outside of the glass? The cold glass cooled the air around it. Then water vapor in the air condensed to small drops of water on the outside of the glass.
Another way matter can change is a chemical change. A chemical change takes place when matter changes into a different kind of matter. An example of a (10) _______________________ change is (11) _______________________ wood. The wood changes into smoke and ash. This chemical change produces heat and light.
Have you ever seen a nail or other piece of metal that was rusted? Rusting is a chemical change, too. The metal in the nails mixes with the air to (12) _______________________ a different kind of matter, rust.
Have you ever seen an old piece of silverware that has turned black? This is another kind of chemical change. A gas in the air causes a black (13) _______________________ called tarnish to form on (14) _______________________ . The tarnish is a different kind of matter from the air or the silver.
Signs of a chemical change are a change in color or temperature or the (15) _______________________ of heat or light. Bubbling, fizzing, or making a noise or smell are some more signs. Not all of these things happen(16) _______________________ a chemical change. But usually at least one of them does happen.
Changes in the way matter looks are physical changes. A physical change happens when matter changes from one state into another. A chemical change takes place when matter changes to a different kind of matter.
Copyright © 2011 edHelper
POST TEST How Matter Changes
|
| ||||
|
| ||||
|
| ||||
|
|
| Name _____________________________ | | Date ___________________ (Key 1 - Answer ID # 0427981) |
|
| ||||||||
|
| ||||||||
|
| ||||||||
|
| ||||||||
|
| ||||||||
|
| ||||||||
|
| ||||||||
|
| ||||||||
|
| ||||||||
|
| ||||||||
|
| ||||||||
|
|
|
| 27. | We used the smelling (Combustion, salts, ph scale) as a restorative after Herman fainted. | |
| 28. | Execretion includes the removal of excess water, (salts, Chemical change, Physical change) , and certain nitrogen wastes. | |
| 29. | The (Thermal expansion, combustion, Magnetism) of firewood smells much better than the combustion of plastic. | |
| 30. | You may use the force of (Thermal expansion, magnetism, Combustion) to hold notes on the refrigerator door. | |
| 31. | We induced (magnetism, Combustion, Reactants) in the nail using a permanent magnet. | |
| 32. | (Acids, Indicator, Products) made from oil or natural gas are petrochemicals. | |
| 33. | The (combustion, Salts, Indicator) of firewood smells much better than the combustion of plastic. | |
| 34. | Oil and coal (Thermal expansion, Acids, combustion) , along with automobile emissions, are the cause of most acid rain. | |
| 35. | Induced (magnetism, Bases, Thermal expansion) occurs when an object like, a nail is stuck to a magnet.. | |
| 36. | Oxidation in which noticeable heat and light are given off is called (combustion, Salts, Bases) . | |
| 37. | Through the process of (Reactants, Thermal expansion, filtration) , water treatment plants ensure that the water we drink is clean. | |
| 38. | chemical weathering occurs when natural (Thermal energy, Reactants, acids) slowly eat into a rock and break if apart. |
| Mixtures By Cindy Grigg | |
1 A mixture is a blend of two or more substances that have NOT combined chemically. A mixture can contain elements, compounds, or both, and in any amounts. In a mixture, each substance keeps its own properties. Substances in a mixture can be separated by physical means. Some different ways to separate the substances in a mixture are:1. Sorting by hand
2. Shaking smaller particles through a sieve
3. Settling out solid particles by letting the mixture stand
4. Using a magnet to separate some metals out of a liquid
5. Passing the substance through a filter paper
6. Distilling to separate two liquids with different boiling points.
2 There are different kinds of mixtures. A heterogeneous mixture is a mixture in which the particles are not spread evenly throughout. Soil, raisin bran cereal, and fruit salad are heterogeneous mixtures.
3 A suspension is a heterogeneous mixture with particles large enough to be seen with the eye or a microscope. A suspension looks cloudy. The particles in a suspension are not dissolved; they will settle out from the force of gravity. Shaking or stirring will suspend the particles again. The particles can be separated out with filter paper. Examples of a suspension are orange juice with pulp or a salad dressing with oil, vinegar, and spices.
4 A homogeneous mixture has particles spread evenly throughout the substance. Tea, root beer, and vinegar are examples of homogeneous mixtures. Each part of the mixture is exactly like every other part.
5 A solution is a homogeneous mixture with very tiny particles of a substance spread evenly throughout. A solution looks like a single substance. The particles will not settle out when the mixture sits for a while, and a filter cannot separate the particles. Salt water is a solution. A solution has the same properties throughout. If you took a small sample from the top, a sample from the middle, and a sample from the bottom, all three would contain the same mixture.
6 Within a solution, one substance is dissolved in another substance. The substance that dissolves is called a solute. The substance into which a solute dissolves is called a solvent. Solutions are not always in liquid form, however. Some gases and solids are also considered solutions. The air we breathe is a solution containing oxygen, carbon dioxide, and some trace gases dissolved in nitrogen. Bronze is a solution of the metals copper and tin.
8 Solubility is the ability of a substance to dissolve in another substance. Sugar is a soluble substance that dissolves easily in water. Carbon dioxide is soluble. It is dissolved in soda to make it "fizz." Hot tea will dissolve more sugar than cold tea. But cold soda will dissolve more carbon dioxide than warm soda. Temperature of the substance affects the solubility. Pressure also affects solubility. What happens when you open a can of soda? Carbon dioxide dissolved in the liquid escapes rapidly from the can. Carbon dioxide is more soluble at higher pressures. When you open the can, you decrease the pressure on the gas, and it comes out of the solution.
Copyright © 2011 edHelper
Mixtures
|
| ||||
|
| ||||
|
| ||||
|
|
Assignment=Please watch this video @mixtures and take between 15-20 notes about it's main ideas and facts
Mixtures
| _____________________________ | ___________________ |
| Mixtures By Cindy Grigg | |
Directions: Fill in each blank with the word that best completes the reading comprehension.
A mixture is a blend of two or more substances that have NOT combined chemically. A mixture can contain elements,(1) _______________________ , or both, and in any amounts. In a mixture, each substance keeps its own properties. Substances in a mixture can be separated by physical means. Some different ways to separate the substances in a mixture are:1. Sorting by hand
2. Shaking smaller particles through a sieve
3. Settling out solid particles by letting the mixture stand
4. Using a (2) _______________________ to separate some metals out of a liquid
5. Passing the substance through a filter paper
6. Distilling to separate two liquids with different boiling points.
There are different kinds of mixtures. A heterogeneous mixture is a mixture in which the particles are not spread evenly throughout. Soil, raisin bran cereal, and fruit salad are heterogeneous mixtures.
A suspension is a heterogeneous mixture with particles large enough to be seen with the eye or a microscope. A suspension looks cloudy. The particles in a suspension are not dissolved; they will settle out from the force of gravity. Shaking or(3) _______________________ will (4) _______________________ the particles again. The particles can be separated out with filter paper. Examples of a suspension are orange juice with (5) _______________________ or a salad dressing with oil, vinegar, and spices.
A homogeneous mixture has particles spread evenly throughout the substance. Tea, root beer, and vinegar are examples of(6) _______________________ mixtures. Each part of the mixture is exactly like every other part.
A solution is a homogeneous mixture with very tiny particles of a substance spread evenly throughout. A solution looks like a single substance. The particles will not settle out when the mixture sits for a while, and a filter cannot separate the particles. Salt water is a solution. A solution has the same properties throughout. If you took a small sample from the top, a sample from the middle, and a sample from the bottom, all three would contain the same mixture.
Within a solution, one substance is dissolved in another substance. The substance that dissolves is called a solute. The substance into which a solute (7) _______________________ is called a (8) _______________________ . Solutions are not always in liquid form, (9) _______________________ . Some gases and solids are also considered solutions. The air we breathe is a solution containing oxygen, carbon dioxide, and some trace gases (10) _______________________ in nitrogen.(11) _______________________ is a solution of the metals copper and tin.
A colloid is a heterogeneous mixture with particles of a size (12) _______________________ that of a solution and a suspension. The particles do not settle out with gravity and cannot be filtered out. Examples of a(13) _______________________ mixture are fog, clouds, cheese, jam, and whipped cream.
Solubility is the ability of a substance to (14) _______________________ in another substance. Sugar is a soluble substance that dissolves easily in water. Carbon dioxide is soluble. It is dissolved in soda to make it "(15) _______________________ ." Hot tea will dissolve more sugar than cold tea. But cold soda will dissolve more carbon dioxide than warm soda. Temperature of the substance affects the solubility. Pressure also affects solubility. What happens when you open a can of soda? Carbon dioxide dissolved in the liquid escapes rapidly from the can. (16) _______________________ dioxide is more soluble at higher (17) _______________________ . When you open the can, you decrease the(18) _______________________ on the gas, and it comes out of the solution.
Copyright © 2011 edHelper
Mixtures
|
| ||||
|
| ||||
|
| ||||
|
|
| 33167) |
| 1. | ability |  |
| 2. | solute | |
| 3. | force | |
| 4. | magnet | |
| 5. | homogeneous | |
| 6. | compounds | |
| 7. | which | |
| 8. | pulp | |
| 9. | bronze | |
|
| 39. | Commercials induce me to buy (products, Thermal energy, Filtration) shown on television. | |
| 40. | Another force that affects us every day is magnetic force, or (magnetism, Chemical change, Products). | |
| 41. | If I shook it, the domains might resettle and the (Bases, magnetism, Physical change) would be gone. | |
| 42. | (Chemical change, Acids, Magnetism) eat away most metals. | |
| 43. | (Filtration, Combustion, Products) produces light and heat. | |
| 44. | Because of the earth's (Salts, Thermal energy, magnetism) , a compass points north. |
| Acids and Bases By Cindy Grigg | |
1 Why does lemonade taste sour? Why does soap feel slippery? What makes cakes rise? These things happen because two kinds of chemicals called acids and bases are at work.2 Acids and bases are important to everyone's health. Acids are sour chemicals, and some are found in everyone's kitchen. The word acid means sour; almost everything sour has acid in it. Vinegar and lemon juice contain acids, and so do grapefruit, green apples, and sour milk. Raspberries, grapes, and many other foods contain acids. Hydrochloric acid, dissolved in a large amount of water, is found in everyone's stomach. It helps us digest our food. Acids flavor foods. They also help turn milk into cheese and cucumbers into pickles. Many vitamins are acids that help our bodies grow. Vitamin C is ascorbic acid. It helps our bodies fight infection and repair wounds. Without enough Vitamin C, people can get a disease called scurvy.
Assignment=Please copy this "Main idea and Details" graphic organizer into your journal and answer the questions there from the reading above.
3 Bases are bitter chemicals often found in kitchens and laundries. Most bases should not be tasted because few of them are foods. Many are bitter poisons. Bases have a soapy, slippery feel on the skin. Egg whites and ammonia are bases, and so are milk of magnesia and many drugs and medicines. Drain openers and oven cleaners are very strong bases. They can damage our skin if we touch them. Hominy is a vegetable we can eat that is made from corn soaked in a strong base. Our blood is a weak base. When bases are cooked with fats or oils, they turn into soap.
Assignment=Please copy this "Main idea and Details" graphic organizer into your journal and answer the questions there from the reading above.
4 Have you ever mixed baking soda and vinegar together? It really bubbles up and usually overflows from the container. This same reaction is what causes cakes to rise. If baking soda is used in the cake recipe, an acid such as buttermilk is also needed. The acid in the buttermilk reacts chemically with the baking soda and causes carbon dioxide bubbles to form, which then causes the cake to rise.
5 We measure the strength of acids and bases with the pH scale. Water is neither an acid nor a base; it is a neutral substance. It measures 7 on the pH scale. Acids have lower numbers than 7; the lower the number, the more acidic the substance is. Milk is a 6 on the scale; soda pop is a 4; vinegar is a 3, lemon juice a 2; and stomach acid is a 1. Bases have higher numbers than 7; the higher the number, the more basic the substance is. Egg whites are 8 on the scale; ammonia is a 10; drain opener is a 12; and oven cleaner is a 13. To test a substance, we use a pH test strip. This is a chemically treated strip of paper that will change color to show whether the substance being tested is an acid or a base. You may have seen someone testing swimming pool water with them. If the substance being tested makes the strip turn a darker color, it is an acid. If the strip turns a lighter color, then it is a base. You simply compare the strip to a color chart to find out the pH of the substance you tested. It is fun to test common household substances to see if they are acids or bases. You might test things like vinegar, orange juice, coffee, and dish soap. Chemistry is fun!Assignment=Please copy this "Main idea and Details" graphic organizer into your journal and answer the questions there from the reading above.
Copyright © 2011 edHelper
| Assignment=Please copy this into your journal and answer the questions there |
|
| ||||
|
| ||||
|
| ||||
|
|
Assignment=Please watch this video @acids and bases and take between 15-20 notes about it's main ideas and facts
Acids and Bases
Assignment=Please copy this into your journal and answer the questions there
| Acids and Bases By Cindy Grigg | |
Directions: Fill in each blank with the word that best completes the reading comprehension.
Why does lemonade taste sour? Why does soap feel slippery? What makes cakes rise? These things happen because two kinds of chemicals called acids and bases are at work.Acids and bases are important to everyone's (1) _______________________ . Acids are sour chemicals, and some are found in everyone's kitchen. The word acid means sour; almost everything sour has acid in it. Vinegar and lemon juice contain acids, and so do grapefruit, green apples, and sour milk. Raspberries, grapes, and many other foods contain acids. (2) _______________________ acid, dissolved in a large amount of water, is found in everyone's stomach. It helps us digest our food. Acids flavor foods. They also help turn milk into cheese and cucumbers into pickles. Many vitamins are acids that help our bodies grow. Vitamin C is ascorbic acid. It helps our bodies fight infection and (3) _______________________ wounds. Without enough Vitamin C, people can get a disease called (4) _______________________ .
Bases are bitter chemicals often found in kitchens and laundries. Most bases should not be tasted because few of them are foods. Many are bitter poisons. Bases have a (5) _______________________ , slippery feel on the skin. Egg whites and ammonia are bases, and so are milk of magnesia and many drugs and medicines. Drain openers and oven cleaners are very strong bases. They can damage our skin if we touch them. (6) _______________________ is a vegetable we can eat that is made from corn soaked in a strong base. Our blood is a (7) _______________________ base. When bases are cooked with fats or oils, they turn into soap.
Have you ever mixed baking soda and vinegar together? It really bubbles up and usually overflows from the container. This same reaction is what causes cakes to rise. If baking soda is used in the cake recipe, an acid (8) _______________________ as buttermilk is also needed. The acid in the buttermilk reacts chemically with the baking soda and causes carbon(9) _______________________ bubbles to form, which then causes the cake to rise.
We measure the strength of acids and bases with the pH scale. Water is neither an acid nor a base; it is a(10) _______________________ substance. It measures 7 on the pH scale. Acids have lower numbers than 7; the lower the number, the more acidic the substance is. Milk is a 6 on the scale; soda pop is a 4; (11) _______________________ is a 3, lemon juice a 2; and stomach acid is a 1. Bases have higher numbers than 7; the higher the number, the more basic the substance is. Egg whites are 8 on the scale; ammonia is a 10; drain (12) _______________________ is a 12; and oven cleaner is a 13. To test a substance, we use a pH test strip. This is a chemically treated strip of paper that will change color to show whether the substance being tested is an acid or a base. You may have seen someone testing swimming pool water with them. If the substance being (13) _______________________ makes the strip turn a darker color, it is an acid. If the strip turns a lighter color, then it is a base. You (14) _______________________ compare the strip to a color chart to find out the pH of the substance you tested. It is fun to test common (15) _______________________ substances to see if they are acids or bases. You might test things like vinegar, orange juice, coffee, and dish soap. Chemistry is fun!
Copyright © 2011 edHelper
§ Physical properties are properties that can be perceived by our senses such as state, color, size, shape, odor, taste, and texture. These are also properties which can be measured by physical means; physical quantities such as volume, length, weight, volume, and temperature; physical constants such as density, specific heat, melting point, and freezing point among others.
§ Physical properties are categorized as extensive or intensive.
§ Intensive - Properties that do not depend on the amount of the matter present such as: color, odor, luster - how shiny a substance is, malleability - the ability of a substance to be beaten into thin sheets, ductility - the ability of a substance to be drawn into thin wires, conductivity, hardness, melting/freezing point, boiling point, and density.
§ Extensive - Properties that do depend on the amount of matter present: mass, weight - a measurement of the gravitational force of attraction of the Earth acting on an object, volume - a measurement of the amount of space a substance occupies, and length – a distance between two points.
§ Chemical properties are the characteristics involved when a substance undergoes change in composition and results in the formation of a new substance. One way of describing the characteristics of a pure substance is by its chemical properties.
§ Physical change is a change in the physical properties of matter. It does not involve a change in the composition of a substance and does not result in the formation of new substance. It is exemplified by a change in the physical state, change in size and shape, change in texture, and a change in physical quantities.
§ A chemical change produces a new substance with different chemical properties. Chemical properties help you describe the way one substance will chemically react with another substance. Color changes, solid formation, bubbles of gas formation, and color disappearance are indicators of chemical changes.
§ Chemical change involves a change in the composition of a substance that results in the formation of new substance with properties that are entirely different from the properties of the original substance. A chemical change is exemplified by corrosion reaction (rusting/tarnishing), combustion reaction, formation of precipitate, formation of gas, change of color, release of heat or light, decaying reactions, fermentation reactions.
§ A mixture is a combination of two or more substances. Each substance in a mixture keeps its individual properties. In a mixture, each part keeps its properties, the parts are not combined in a set ratio and the parts can be separated by physical means.
§ Properties such as particle size, boiling point, solubility, and density can be used to separate mixtures.
§ A homogeneous mixture has the same uniform appearance and composition throughout. Many homogeneous mixtures are commonly referred to as solutions.
A solution is a mixture of two or more substances in a single phase. At least two substances must be mixed in order to have a solution. The substance in the smallest amount and the one that dissolves or disperses is called the solute. The - this process when we want to collect the solvent (liquid) from a mixture of solid and liquid, or when we want to separate two liquids that are soluble in each other. E.g. Alcohol and water can be separated by distillation. The liquid collected by distillation is called a distillate. To use this technique effectively, it is important that the solvent or one of the liquids (in the second case) has a lower boiling point then the other.
- Evaporation – It is used to separate dissolved soluble solids from the liquid in the solution-mixture. The mixture is heated and the liquid is converted into vapor. The solid is left behind as residue. It is important that the solid does not decompose when heated. This method is suitable to separate a soluble solid from a liquid. If the solution is heated, the liquid evaporates leaving the solid behind.
- Fractional Distillation - This is a special type of distillation used to separate a mixture of liquids. Different liquids boil at different temperatures. When heated, they boil off and condense at different times. The apparatus features a fractionating column, which ensures that only the liquid boils at its boiling point will pass into the condenser.
- Filtration – It is the process by which insoluble solids in a solution can be separated. In this technique the soluble solids are trapped in a filter paper. The liquid passes through the filter paper. The trapped solid particles are called residue and the liquid collected is call the filtrate. The physical properties to be kept in mind are solubility and particle size. To separate an insoluble solid from a liquid. The solid remains in the filter paper and the liquid goes through the paper into the beaker.
- Some of the example mixtures that can be separated using the above mentioned techniques:
(1) separating dyes in inks, or chlorophyll in plants (ethanol as solvent) - chromatography
(2) separating sand from water - filtration
(3) separating ethanol and water - fractional distillation
(4) separating water from ink - simple distillation
(5) separating salt from water - evaporation
(1) separating dyes in inks, or chlorophyll in plants (ethanol as solvent) - chromatography
(2) separating sand from water - filtration
(3) separating ethanol and water - fractional distillation
(4) separating water from ink - simple distillation
(5) separating salt from water - evaporation
§ Acids taste sour, are corrosive to metals, change litmus (a dye extracted from lichens) red, and become less acidic when mixed with bases.
§ Bases feel slippery, change litmus blue, and become less basic when mixed with acids.
§ The most striking property of both acids and bases is their ability to change the color of certain vegetable materials. A common vegetable whose color responds to acids and bases is red cabbage.
§ Acidic and basic are two extremes that describe a chemical property chemical. Mixing acids and bases can cancel out or neutralize their extreme effects. A substance that is neither acidic nor basic is neutral.
There are substances which have the property of changing their color when they come in contact with an acidic or basic environment. These substances are called pH indicators. Usually, they are used as dissolved substances, as for instance phenolphthalein and bromothymol blue. Often, to measure the pH, special papers which have been soaked with indicators are used. These papers § change color when they are immersed in acidic or basic liquids. This is the case of the well-known litmus paper.
§ The pH scale measures how acidic or basic a substance is.
§ The pH scale ranges from 0 to 14. It measures the acidity or basicity of a solution. A pH of 7 means it is a neutral solution. Pure water has a pH of 7. A pH of less than 7 means the solution is acidic. A pH of more than 7 means the solution is basic. The less pH, the more acidic the solution is. The more pH, the more basic the solution is.
§ pH stands for the power of H, or the amount of H+ ions acids or bases take or contribute in solution. pH equals the negative log of the concentration of H+ (pH = -log[H+]). When the concentration of H+ ions in a solution is 10-14, the pH is 14. In pure water, the average concentration of H+ ions is 10-7.
§ pH can also be measured by a hydrogen sensitive electrode also referred to as a pH meter.
§ Another easy way that you can measure pH is with a strip of litmus paper.
§ Litmus is a substance obtained from certain lichens. When you touch a strip of litmus paper to something, the paper changes color depending on whether the substance is acidic or basic. If the paper turns red, the substance is acidic, and if it turns blue, the substance is basic.
§ solvent. In most common instances water is the solvent. The gases, liquids, or solids dissolved in water are the solutes.
§ A heterogeneous mixture consists of visibly different substances or phases of matter
§ Particle size distinguishes homogeneous solutions from other heterogeneous mixtures. Solutions have particles which are the size of atoms or molecules - too small to be seen. In contrast a suspension is a heterogeneous mixture of larger particles. These particles are visible and will settle out on standing. Examples of suspensions are: fine sand or silt in water or tomato juice.
§ A colloid is a homogeneous solution with intermediate particle size between a solution and a suspension. Colloid particles may be seen in a beam of light such as dust in air in a "shaft" of sunlight. Milk, fog, and jello are examples of colloids.
§ Two liquids that are soluble in each other. E.g. Alcohol and water can be separated by distillation. The liquid collected by distillation is called a distillate. To use this technique effectively, it is important that the solvent or one of the liquids (in the second case) has a lower boiling point then the other.
§ Mixtures can be separated into their constituents by using physical methods (i.e. no chemical reaction involved). Separation techniques are physical methods. Which technique to use depends on the different properties of the constituents. That is, different states, solubility, boiling and melting points.
§ Separation is the process by which a mixture is physically broken down into its components. It can be done because components of mixtures retain their individual properties unlike compounds. Selection of appropriate separation techniques involves devising or selecting a process that selects components with certain physical properties like size, weight, density, magnetic properties, melting point, boiling point, solubility, etc.
§ Separation Techniques:
- Crystallization: It is a process in which we keep on adding more of the solid to the hot solution (solid - liquid mixture), until no more added solid can be dissolved by the solution. Such a solution is called a saturated solution. A small object is lower down into the still-hot solution. This object is call 'seed'. As the solution cools, the solid particles dissolved will start collecting around the seed. This is useful for solids that decompose on heating
- Magnetic Separation: It is used to separate magnetic substances in a mixture from non-magnetic ones. Useful in mining industry to separate iron from other compound in mixtures.
- Chromatography - To separate different colored dyes. This technique is used when one or more constituents of a mixture travel faster than the others on an absorbent material (like paper). It is useful to separate fine solids dissolved in a liquid. Also useful to identify the colored constituents in dyes. The dyes travel up the chromatography paper at different distances before they cannot remain in solution. The more soluble dyes move further up than the less soluble ones, hence separating from each other.
Distillation - to separate and collect a liquid from a solution of a soluble solid. The solution is heated in a flask until the liquid boils. The vapor produced passes into the condenser where it is cooled and condenses to a liquid. The pure liquid (distillate) is collected in a beaker. We use | POST TEST |
Learning Activities and Strategies | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Activity | Description | Materials | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
“Metallic Breakfast” Through a teacher demo, students will observe the separation of iron filings from iron-fortified breakfast cereal. | Procedure 1. Place a stirring bar in a 400 ml beaker. 2. Add about 30 g of cereal to the beaker. 3. Add water until the beaker is about half full. 4. Using a magnetic stirrer, mix gently for About 20 minutes. 5. Retrieve the stirring bar and observe the Black iron filings attached to it. | Iron-fortified breakfast cereal 400 ml beaker Distilled water Magnetic stirrer with stirring bar | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
“Paper Chromatography” Students will perform an experiment to separate the components of mixtures using paper chromatography. | Procedure 1. Use the marking pen to draw a line across a strip of filter paper. The line should be 2 cm from one end of the strip. 2. Tape the unmarked end of the filter paper to the center of a pencil so that the strip hangs down when the pencil is held horizontally. 3. Working in a well-ventilated room, pour rubbing alcohol into a plastic cup to a depth of 1cm. 4. Rest the pencil on the rim of the cup so that the ink end of the strip touches the rubbing alcohol, but does not extend below its surface. Use plastic wrap to cover the top of the cup. 5. Observe the setup for 15 minutes. Analyze and Conclude 1. How did the appearance of the filter paper change during the procedure? 2. What evidence is there that green ink is a mixture? 3. How could you use this procedure to identify an unknown type of green ink?
| Clear plastic wrap Green marking pen Filter paper strip Metric ruler Clear plastic tape Pencil Rubbing alcohol Clear plastic drinking cup | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Subscribe to:
Posts (Atom)