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Home , Concentration, Solubility, Solubility table

2 and What You’ll Learn 6(E) • what solubility is • about the concentration of Before You Read The labels of some containers of fruit juice say “Not from • three types of solutions concentrate.” What do you think this means? • factors that affect solutions

Read to Learn Focus Check for Understanding As How much can dissolve? you read this section, highlight Suppose you like your lemonade very sweet. You add a any sentences that you read teaspoon of sugar to it and stir. The sugar dissolves. If you keep more than once. After you finish the section, go back and read adding sugar to the lemonade, you will reach a point when no more the highlighted sentences again. sugar will dissolve in it. The excess sugar crystals fall to the bottom of the glass. They do not go into the . You have reached the solubility of sugar in a given amount of . Solubility (sahl yuh BIH luh tee) is the greatest amount of solute that can dissolve in a specific amount of at a given . Are the of all substances the same? You can dissolve more than 32 g of in 113 g of water at 25°C. But, you can only dissolve about 12 g of baking soda in 113 g water. Salt and baking soda have different solubilities in water. The difference in the solubilities of solutes depends on the nature of the solute and the nature of the solvent.

Concentration Suppose you and a friend are making lemonade. You add one teaspoon of lemon juice to a glass of water. Your friend adds four teaspoons of lemon juice to the same amount of water. Your friend’s glass has more flavor. It has a large amount of solute dissolved in the solvent. It is concentrated. Yours is dilute because it has less solute. Concentration of a solution measures the amount of solute

Copyright © McGraw-Hill Education. Permission is granted to reproduce for classroom use. classroom for reproduce to is granted Permission Education. © McGraw-Hill Copyright dissolved in a given amount of solvent.

Reading Essentials • Solutions 381

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Program: TX HS Science Component: IPC RDNG ESNTLS PDF PASS Vendor: LASERWORDS Grade: N/A How much solute is in a concentrated solution? Think it Over Concentrated and dilute are not precise terms. Concentra-tion 1. Identify Which of the of solutions can be described precisely, though. One way is to concentrated drink solution state the concentration as a percentage by volume of the solute. ingredients is the solute? (Circle your answer.) For example, the label on a bottle of orange-flavored drink states a. 10 mL that the drink contains 10 percent fruit juice. This means that in b. 90 mL 100 mL of the drink, there are 10 mL of juice. Or, to make 100 mL c. 100 mL of a 10 percent solution of orange drink, the manufacturer added 10 mL of juice to 90 mL of water. To be sure you are getting the highest concentration of juice, choose a drink that is 100 percent juice.

GET IT? Types of Solutions 2. Explain What is solubility? Each solute has its own solubility—the maximum amount of solute that can be dissolved in a given amount of solvent. Solutions are defined then as saturated, unsaturated, or supersaturated. What is a saturated solution? The table lists the solubilities of some compounds in 100 g of water at different . If you add 35 g of copper(II) , CuSO4, to 100 g of water at 20°C, only 32 g will dissolve. The solution is saturated. A saturated solution is a solution that contains all the solute it can hold at a given temperature. If you increase the temperature of the , more copper(II) sulfate can dissolve. As shown in the table, the Copyright © McGraw-Hill Education. Permission is granted to reproduce for classroom use. solubility of solutes increases as the temperature of the solvent increases.

Solubility of compounds in g/100 g of water Compound 0°C 20°C 100°C

Copper(ll) sulphate 23.1 32.0 114

Potassium 53.6 65.3 104

Apply Math 28.0 34.0 56.3 3. Use a Table How many grams of sugar are needed Potassium 13.9 31.6 245 to make a saturated solution of sugar in 100 g of water Sodium 79.6 95.9 204 at 20°C? 35.7 35.9 39.2

Sucrose (sugar) 179.2 203.9 487.2

Reading Essentials • Solutions 382

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Program: TX HS Science Component: IPC RDNG ESNTLS PDF PASS Vendor: LASERWORDS Grade: N/A What is a solubility curve? The graph shows some of the information from the table on the Apply Math previous page. Each line on the graph is a solubility curve for a 4. Use a Graph About how substance. You can use this to find how much solute dissolves in 100 much g of water at a given temperature. To find how much sodium is needed to make a chloride, NaCl, dissolves in 100 g of water at 50°C, find 50°C on the saturated solution in 100 g of x-axis. Trace a line upward from 50°C to the curve for NaCl. Read water at 80°C? the amount shown on the y-axis at that point. About 35 g of NaCl dissolves in 100 g of water at 50°C. As the temperature of the water increases, more solute can dissolve. This is true for most liquid and solid solutes.

Temperature Effects on Solubility 240 Think it Over Potassium nitrate 200 5. Explain As the temperature (KNO3) of the water increases, what 160 happens to the amount of Sodium solid solute that can be chlorate dissolved? (Circle your 120 (NaClO3) answer.) 80 Potassium a. It does not change. bromide (KBr) b. Less can dissolve. 40 Sodium chloride c. None can dissolve. (NaCl) Solubility (grams per 100 g of water) Solubility (grams 0 d. More can dissolve. 0 102030405060708090 Temperature (°C) What is an unsaturated solution? You learned that 32 g of copper(II) sulfate forms a saturated solution with 100 g of water at 20°C. What if a solution has less than 32 g of copper(II) sulfate? Then it is an unsaturated solution, a solution that can dissolve more solute at a given temperature. The term unsaturated solution is not precise. You know exactly how much copper(II) sulfate makes a saturated solution in 100 g of water at 20°C. An unsaturated solution can have any amount of copper(II) sulfate less than 32 g in 100 g of water at 20°C. How can a solution be supersaturated? Think it Over Suppose you make a saturated solution of potassium nitrate 6. Infer Would a solution made of 30 g of copper(II) sulfate (KNO3) with 100 g of water at 100°C. You add 245 g of (KNO3) to dissolved in 100 g of water at the water, just as the shows. You then let the 20°C be a saturated or an Copyright © McGraw-Hill Education. Permission is granted to reproduce for classroom use. classroom for reproduce to is granted Permission Education. © McGraw-Hill Copyright solution cool to 20°C. What happens? Some of the (KNO3) solute unsaturated solution? comes out of solution and falls to the bottom of the container. You can see from the table that at 20°C only 31.6 g of (KNO3) dissolves in 100 g of water. At the lower temperature, the solvent cannot hold as much solute. Reading Essentials • Solutions 383

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Program: TX HS Science Component: IPC RDNG ESNTLS PDF PASS Vendor: LASERWORDS Grade: N/A Most saturated solutions behave the same way as the potassium nitrate solution when cooled. But some solutions can become supersaturated. A supersaturated solution is a solution that has more solute than a saturated solution at the same temperature. For example, if you cool a saturated solution of sodium from 100°C to 20°C, no solute comes out of the solution. This solution is supersaturated. A supersaturated solution is unstable. If a crystal of is dropped into this solution, crystals begin to form. The extra sodium acetate comes out of solution. When do solutions give off energy? The supersaturated sodium acetate solution becomes hot as Think it Over sodium acetate crystallizes. New bonds form between the sodium acetate ions and water molecules. Sometimes when bonds form, 7. Apply What is happening when a solution gets colder? energy is given off in the form of heat. Some heat packs are filled with a supersaturated solution that gives off heat as the solute crystallizes. Some solutes take energy from their surroundings to dissolve. As a result, the temperature of the solution is reduced. nitrate is an example. A cold pack has inner bags of water and . A solution forms when the inner bags are broken. The ammonium nitrate draws energy from the water as the solution forms. The water temperature drops and the pack feels cool. Copyright © McGraw-Hill Education. Permission is granted to reproduce for classroom use. Solubility of Soda is a solution of gas dissolved in flavored water. When you shake an open bottle of soda, it bubbles. Shaking or stirring a solution of a gas in a liquid allows more gas molecules to reach the surface of the liquid, where they escape from the liquid into the air. How do and temperature affect a gas dissolved in a liquid? Think it Over Increasing the pressure of a gas over a liquid more gas to 8. Draw Conclusions How dissolve in the liquid. Soda is bottled under a large amount of could you make the bubbles pressure. The pressure increases the amount of gas that can come out of solution before dissolve in the soda and also keeps the carbon dioxide gas in you drink a soda? solution. When you open a bottle of soda, the pressure is released and bubbles of gas come out of solution. Cooling a liquid increases the amount of gas that will dissolve in it, the opposite of dissolving amounts of most in a liquid. Less gas is able to dissolve in warm . This is why warm soda bubbles up more than cold soda. Reading Essentials • Solutions 384

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Program: TX HS Science Component: IPC RDNG ESNTLS PDF PASS Vendor: LASERWORDS Grade: N/A After You Read Mini Glossary concentration: how much solute is present in a solution compared to supersaturated solution: a solution that has more solute than a the amount of solvent saturated solution at the same temperature saturated solution: a solution that contains all the solute it can hold unsaturated solution: a solution that can dissolve more solute at at a given temperature a given temperature solubility: the greatest amount of solute that can dissolve in a specific amount of solvent at a given temperature

Review 1. Study the terms and their definitions in the Mini Glossary. Write a sentence using one of the terms that describes a type of solution.

2. Complete the table below to help you organize the information you learned about solubility and types of solutions.

Does it Does it depend Type of Solution How is it made? depend on on the amount temperature? of solute?

Saturated

Unsaturated

Supersaturated

3. As you read this section, you highlighted the sentences that you read more than once. How could you use this strategy if you were studying with a friend? Copyright © McGraw-Hill Education. Permission is granted to reproduce for classroom use. classroom for reproduce to is granted Permission Education. © McGraw-Hill Copyright

Reading Essentials • Solutions 385

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Program: TX HS Science Component: IPC RDNG ESNTLS PDF PASS Vendor: LASERWORDS Grade: N/A