7.1 & 7.2 Check and Reflect - Science PDF

# Check and Reflect ## 7.1 1. Fill in the blanks with the correct terms so that the paragraph explains classifying matter. You may have to use some words more than once. > Most matter can be classified as a pure substance or a **mixture**. Sugar is a **pure substance** because it is made of only...

# Check and Reflect ## 7.1 1. Fill in the blanks with the correct terms so that the paragraph explains classifying matter. You may have to use some words more than once. > Most matter can be classified as a pure substance or a **mixture**. Sugar is a **pure substance** because it is made of only **one** type of substance. Many other foods are **mixtures** because they are made up of **more than one** substance. 2. Match the descriptions below with the correct term. - pure substance (b) - mixture (d) - solution (a) - mechanical mixture (c) (a) a mixture in which you cannot see the different substances (b) matter that is made of only one substance (c) a mixture in which you can see the different substances (d) matter that is made of more than one substance 3. Complete the table below by putting the following materials in the column where you think they belong: pure vanilla extract, granola bar, apple juice, tomato sauce | Mixture | Pure Substance | |---|---| | granola bar | pure vanilla extract | | tomato sauce | apple juice | 4. Categorize the following substances as either a pure substance or a mixture. Beside each substance, write PS (pure substance) or M (mixture). (a) vanilla ice cream **M** (b) salt **PS** (c) hot chocolate **M** (d) oxygen **PS** (e) olive oil **PS** 5. Place the following descriptions in a Venn diagram. - You can see the substances that make it up - You cannot see the substances that make it up - Substances are not dissolved - Substances are in solution - Is a mixture - Contains different substances See answer to Venn diagram on page 112. ## 7.2 1. Fill in the blank with the term that makes each statement true. kinetic energy (a) The particles in a pure substance are **identical** particles (b) All matter is made up of **particles** (c) The particles of a mixture are **different** (d) Particles that are moving have **kinetic energy** 2. Beside each description, write the word that best identifies the state of matter described. - solid - liquid - gas (a) strong force of attraction **solid** (b) medium force of attraction **liquid** (c) weak force of attraction **gas** (d) particles far apart **gas** (e) medium space between the particles **liquid** (f) small space between the particles **solid** 3. For each change of state, explain whether heat is added or taken away to make the change. Write either Added or Taken Away in the space provided. (a) from a solid (ice) to a liquid (water) **Added** (b) from a gas (steam) to a liquid (water) **Taken Away** (c) from a liquid (water) to a solid (ice) **Taken away** (d) from a liquid (water) to a gas (steam) **Added** 4. Which picture represents the particles in a block of ice ? (a) (b) (c) 5. Which statement describes what is happening to the particles in a candle as the flame heats up the solid wax and turns it to liquid? (a) The particles get more kinetic energy and come closer together. (b) The particles lose kinetic energy and come together. (c) The particles get more kinetic energy and spread out. (d) The particles lose kinetic energy and spread out. ## Chapter Review ### Key Terms 1. For the terms listed below, circle the symbol that best describes how well you understand what the term means. - matter - pure substance - mixture - mechanical mixture - solution - dissove - particle - particle theory of matter - kinetic energy ### Questions 2. Choose one of the foods listed below. Draw a diagram and add labels to show why the food is a mixture. - milkshake - granola - pizza Student diagrams should include the different substances that are a part of the food they have chosen. 3. After a cold night, frost and ice crystals form on the windshields of cars left outside. Use the particle theory and change of state to explain how this happened. You can write your answer or draw a labelled diagram. > As heat is taken away, the water vapour particles in the air lose energy and move closer together, condensing on the cold surface of the windshield. 4. Use the particle theory of matter to explain why sugar is a pure substance. You can write your answer or draw and label a diagram. > Written answers or diagrams should explain or show that sugar particles are all the same and have the same properties. 5. Use the following words in a diagram showing how matter can be classified: matter, pure substance, mechanical mixture, solution, mixture. ## 7.2 Revisited Go back to the beginning of this chapter and look over the way you connected the different symbols and words. Using a different colour pen or a highlighter, add any new connections that you can now make, and change any of the connections you had made before to show your understanding of the information and ideas from this chapter. List three different ways that water is used in your community. For each use, describe the use and tell if the water is returned to the environment clean or dirty. > Students should recognize that water is used for drinking, cooking, washing, cooling, and cleaning, and that it is almost always returned to the environment dirty. ## 8.0 Mixtures and solutions can be analyzed through concentration, solubility, and concentration. (See Student Book pages 210-213) Mixtures and solutions can be mixed and separated in various ways. In this chapter, you will learn more about: - mixing different amounts of materials to produce very different mixtures and solutions - the factors that affect how substances and mixtures combine - separating mixtures and solutions Look at the symbols and the words on this page. Use a pencil to link some of the different pictures and words that you think are connected. Write or draw what you think the connection is. ## 8.1 Solutions: Concentration and Solubility (See Student Book pages 214-219) Solutions are mixtures in which substances are evenly mixed throughout. In a solution, the different parts cannot be seen. Solutions are made when one substance dissolves in another. Solutions consist of a solute and a solvent. A solute is a substance that can dissolve in a solvent. A solvent is a substance into which a solute can dissolve. > Teaching Note: Tell students that "solute" and "solvent" come from the Latin verb "solvere," which means to dissolve or loosen. In the diagram above, label the solvent. Label the solute. If you saw the diagram after the solute had been mixed into the solvent, could you still label the solvent and the solute? Why or why not? > The water is the solvent and the sugar is the solute. You couldn't label them after they were mixed because you wouldn't be able to see the particles of solute. Solutions can be solids, liquids, or gases. | Solution | Solute | Solvent | |---|---|---| | Brass | Zinc (solid) | Copper (solid) | | Seawater | Salt and minerals (solid)| Water (liquid) | | Soft drink | Carbon dioxide (gas) | Water (liquid) | | Air | Oxygen, argon (gas) | Nitrogen (gas) | > solute: a substance that can dissolve in a solvent to form a solution > solvent: a substance in which a solute dissolves ## 8.1 Check & Reflect 1. Beside each description, write the word that describes it. - solute - solvent - saturated - dilute (a) when no more material can be dissolved in water **saturated** (b) a substance that can dissolve in another substances **solute** (c) a material that will dissolve other substances **solvent** (d) when there is very little solute dissolved in a lot of solvent **dilute** 2. Fill in the blanks with the correct words so that the paragraph describes solutions. > When you add sugar to water, you are making a **solution**. If you add only a little sugar to the water, the solution will be **dilute** . It will be an **unsaturated**solution. If you add too much sugar to the water, **some** of the crystals will sit on the bottom of the container because the solution is **saturated**. 3. Read the following statements about water. If they are true, circle T; if they are false, circle F. (a) Water is a universal solvent because it can be a solid, a liquid, or a gas. **T F** (b) Water is present in every solution. **T F** (c) Water is a universal solvent because many different solids, liquids, and gases dissolve in it to make solutions. **T F** (d) Water is a solute. **T F** 4. Read the following statements about solutions. If they are true, circle T; if they are false, circle F. (a) Food colouring does not dissolve in water. **T F** (b) A solute can dissolve in a solvent. **T F** (c) Sand particles can dissolve in water. **T F** (d) Substances dissolve because particles of the solute are attracted to particles of the solvent. **T F** 5. In the pairs below, which solution is more dilute? (a) a package of fruit crystals dissolved in a 500-mL bottle of water (b) a package of fruit crystals dissolved in a 1000-mL bottle of water (a) one spray of air freshener in the gym change room (b) one spray of air freshener in the school gymnasium ## 8.2 Factors AffectingSolubility (Why Things Dissolve) (See Student Book pages 220-226) Solubility and the Particle Theory > Earlier you learned that: * all matter is made up of particles * particles are always in motion * the solute particles in a solution are attracted to the particles of the solvent Complete the following paragraph using the following words: *bump, attraction, solute, move, solvent, moving* >According to the particle theory of matter, the particles of a solvent and a solute are **always moving**. The particles constantly **move** from place to place. The particles of **solute** have a greater **attraction** for the **solvent** than they do for other particles of solute. As they move around, they **bump** into each other. This means that the solvent particles can free the tiny particles from the **solute** and move them into solution. Each solute particle is then carried away by bumping into the **solvent** particles. This allows the solvent particles to surround the **solute particles** evenly throughout. ### Rate of Dissolving > You and a friend are making hot chocolate. You add a spoonful of chocolate powder to some milk from the fridge. Most of the powder seems to just sit on top of the milk. Your friend has made her hot chocolate already. What two things do you think she did to make the chocolate powder dissolve faster? What could you have done to make your chocolate powder dissolve faster? Students should be able to answer based on their own experience. Students should be able to suggest that stirring the mixture and heating the milk would help their chocolate powder to dissolve. > How quickly a solute will dissolve in a solvent is called the **rate of dissolving**. Three different factors can affect the rate of dissolving. They are: * stirring * particle size * temperature > Teaching Note: The question about hot chocolate is theoretical at this point. It prepares students for the material to follow. > rate of dissolving: how fast a solute dissolves in a solvent ## 8.2 Check & Reflect 1. Fill in the blanks with the correct words so that the paragraph explains some of the factors that can affect how well a solvent dissolves a solute. > To make a solute go into solution faster, **stir** or **heat** the solution. These actions will make the particles move faster and dissolve more quickly. You can break up a large solid solute and make the **particle size** smaller to make the solute go into solution faster. These actions affect the **rate of dissolving**. 2. Number the statements in order so that they correctly explain the process of solute particles mixing with solvent particles. 1. Particles are added to the solvent. 2. Particles spread out in the solvent. 3. Solute particles are attracted to the solvent particles. 4. Solute particles are attracted evenly spread out in the solution. 3. Which of the following items would you use to dissolve a sugar cube in 400 mL of water? Be prepared to explain how you would use the items to dissolve the sugar. (a) rolling pin - to break down the sugar cube (b) food colouring (c) hot plate - to heat up the water (d) spoon - to stir the solution 4. In each of the pairs below, which solute will dissolve faster in water? Be prepared to explain your answer. (a) a cube of brown sugar (b) crystals of brown sugar (a) a cube of a soup broth mixture (b) powdered broth mix > In both cases, particles of the solute will come into contact with the solvent particles quicker as crystals or powder than as a solid block. 5. Which factor does not affect the rate of dissolving? (a) temperature of the solvent (b) particle size of the solute (c) shape of the container (d) stirring the solution while mixing the solute and solvent 6. Which actions will help a package of hot chocolate powder to dissolve more quickly? (a) heating the water (b) using pure water (c) blowing on the hot water (d) putting the powder and the hot water in a mixer ## 8.3 Separating Solutions and Mechanical Mixtures (See Student Book pages 227-234) ### Separating Solutions Mixtures and solutions are made up of different substances. These substances can be separated. The methods used to separate them depend on the type of mixture or solution and the substances involved. When a solution is separated, you can see the different parts of the solution. ### Paper Chromatography Chromatography is one way of separating a mixture. It makes use of water's ability to dissolve substances. It separates a solution of water-soluble colour markers and water. ### Evaporation Evaporation can be used to remove the solute from a solution. If you heat a solution of salt water, the heat will give the water particles kinetic energy. When the water particles get enough energy, they will change to a gas, or evaporate. When all the water has evaporated, the salt particles will be left behind. In the solution shown below, the circles represent water particles, and the boxes represent salt particles. Draw what you think should be in the container below, now that all of the water has evaporated. > Water particles > Salt particles > Water particles get more energy as the water is heated. They eventually evaporate into the air > Teaching Note: Point out that if you keep on heating a solution, evaporation will not stop until all of the solution is gone. That's why food in a saucepan can burn if the owner leaves it on the heat and forgets about it. All of the liquid evaporates and the solids that are left get burnt. > evaporate: when matter changes from a liquid to a gas (for example, water to steam) ### Distillation Distillation is another way to separate solutions. When a solution is heated, the liquid boils and the solvent begins to evaporate. The boiled liquid is now a gas. The gas flows over a cool surface. The cool surface makes it condense. The solute stays in the container. Distillation can separate solids or liquids that are in solution. ### Separating Mechanical Mixtures In mechanical mixtures, substances are often very different from one another. When you separate a mechanical mixture, you are able to see the different parts of the mixture. Separating the parts is easy. ### Filtration Filtration is the process used to remove solid substances from a mixture. You can separate a mixture of sand and water by filtering them. Look at the diagram below. Use the listed terms to correctly label the diagram. Why does the filter work? > Teaching Note: Check the mixtures mind map for any mechanical mixtures that have been listed. Have students check to see that the information here applies (an ice cream sundae would be difficult to separate physically, but it's easy to see its different parts). >filter ->dirty water -> sand -> clean water > Labels: sand, filter, clean water, dirty water > The sand particles can't get through the filter. The water particles can get through. > Filtering is a good way to clean water. ### Sorting When the parts of a mixture are easy to see, they can be separated by sorting. The parts of a mixture can be sorted by shape, colour, size, and so on. Recycled waste is a mixture of different types of recycled goods. They can be sorted into different groups based on what they are made from. > filtration: a process used to remove solid substances from a mixture ### Sifting Separating a mixture of different solids can be done by sifting. Sifting involves shaking a solid through a screen or mesh. Sifting sorts the parts of a mixture by size. For example, gravel contains stones of many different sizes as well as sand. However, a screen can be used to separate the sand from the stones. > Large particles cannot pass through the screen. Depending on the size of the screen, you can decide what parts of a mechanical mixture you want to separate from the rest. > Why might sifting and sorting be good methods of looking for gold among the soil and small rocks that sit at the bottom of a river? The soil and water will pass through the screen, making it easier to sort through the stones to look for gold. ### Magnetism Materials made of metal can be separated from other substances by using a magnet. Metals such as iron, nickel, and steel are attracted to magnets. > Large magnets can be used to separate metals from materials such as plastics, which are not attracted to magnets. >How would you separate water, sugar, marbles, and nickels? You could use sorting for the marbles, magnetism for the nickels, and distillation for the sugar/water mixture. ## 8.3 Check & Reflect 1. Beside each description, write the word that describes the best method for separating the mixture into its different parts. - chromatography - magnetism - sifting - sorting - filtration - evaporation (a) mixture of steel nails from brass screws and plastic washers **magnetism** (b) sugar from a watery sweet mixture **evaporation** (c) clumps of salt from salt crystals **sifting** (d) colour dyes from a marker **chromatography** (e) pens, pencils, and markers in your pencil case **sorting** (f) particles of dust from the air in your house **filtration** 2. Read the following statements about separating solutions and mixtures. If they are true, circle T; if they are false, circle F. (a) Recycled materials can be separated by sifting. **T F** (b) Distillation separates a solution of two liquids. **T F** (c) Filtering can be used to separate a sand and water mixture. **T F** (d) Magnetism can be used to separate all metals. **T F** 3. Which of the following makes paper chromatography possible? (a) solvent particles are attracted to paper (b) the paper filters the sample liquid (c) the sample tested is soluble in the solvent (d) there is more than one solute in the solvent 4. A recycling company would like to remove garden waste from household garbage. It has installed green bins so homeowners can collect their garden waste. Which term describes this separation method? (a) filtration (b) sifting (c) magnetism (d) sorting 5. What makes sifting possible? (a) The material is magnetic. (b) The material will dissolve in water. (c) The materials are of different sizes. (d) The materials have different particles that can be seen.