# solubility and concentration

## concentration

The concentration of a solution is the amount of solute in a given amount of solution. A solution with little dissolved solute has a low concentration. It is called a dilute solution. A solution with a lot of dissolved solute has a high concentration. It is called a concentrated solution. Concentration is often expressed as a percent. You can calculate the concentration of a solution using this formula: Concentration = Mass (or Volume) of Solute 100% Mass (or Volume) of Solution For example, if a 100 g solution of salt water contains 3 g of salt, then its concentration is: Concentration = 3g 100% = 3% 100 g For some problems that are more challenging, go to these URLs: MEDIA Click image to the left or use the URL below. URL: MEDIA Click image to the left or use the URL below. URL: You Try It! Problem: A 1 L container of juice drink, called brand A, contains 250 mL of juice. The rest of the drink is water. How concentrated is brand A juice drink? Problem: A 600 mL container of another juice drink, called brand B, contains 200 mL of juice. Which brand of juice drink is more concentrated, brand A or brand B?

## saturation

There is a limit on the amount of solute that can dissolve in a given solvent. Tanya found this out with her baking soda mixture. But even sugar, which is very soluble, has an upper limit. The maximum amount of table sugar that will dissolve in 1 L of water at 20C is about 2000 g. If you add more sugar than this, the extra sugar wont dissolve. A solution that contains as much solute as can dissolve at a given temperature is called a saturated solution. A solution that contains less solute than can dissolve at a given temperature is called an unsaturated solution. A solution of 2000 grams of sugar in 1 L of 20C water is saturated. Thats all the sugar the solution can hold. Any solution containing less than 2000 g of sugar is unsaturated. It can hold more sugar. To learn more about saturated and unsaturated solutions, watch the video at this URL: . You Try It! Problem: A solution contains 249 grams of Epsom salt in 1 L of water at 20C. Is the solution saturated or unsaturated? Problem: Give an example of an unsaturated solution of table salt in 1 L of 20C water.

## factors that affect solubility

Certain factors can change the solubility of a solute. Temperature is one such factor. How temperature affects solubility depends on the state of the solute, as you can see in Figure 10.3. If a solute is a solid or liquid, increasing the temperature increases its solubility. For example, more sugar can dissolve in hot tea than in iced tea. If a solute is a gas, increasing the temperature decreases its solubility. For example, less carbon dioxide can dissolve in warm ocean water than in cold ocean water. The solubility of gases is also affected by pressure. Pressure is the amount of force pushing against a given area. Increasing the pressure on a gas increases its solubility. Did you ever open a can of soda and notice how it fizzes out of the can? Soda contains carbon dioxide. Opening the can reduces the pressure on the gas so it is less soluble. As a result, some of the carbon dioxide comes out of solution and rushes into the air. Do you wonder why temperature and pressure affect solubility in these ways? If so, watch the video at the URL below. It explains why.

## solubility

Solubility is the amount of solute that can dissolve in a given amount of solvent at a given temperature. Some solutes have greater solubility than others in a given solvent. For example, table sugar is much more soluble in water than is baking soda. You can dissolve much more sugar than baking soda in a given amount of water. Compare the solubility of these and other solutes in Figure 10.2. For a video about solubility, go to this URL: MEDIA Click image to the left or use the URL below. URL:

## instructional diagrams

No diagram descriptions associated with this lesson

## questions

solution with a low concentration of solute

``````a. solubility

b. saturated solution

c. concentration

-->  d. dilute solution

e. unsaturated solution

f. concentrated solution

g. pressure
``````

Which statement about solubility is true?

``````a. Solubility is the same for all solutes in a given solvent.

-->  b. Solubility depends on the temperature of the solvent.

c. Solubility always increases when temperature increases.

d. two of the above
``````

solution that contains less solute than can dissolve at a given temperature

``````a. solubility

b. saturated solution

c. concentration

d. dilute solution

-->  e. unsaturated solution

f. concentrated solution

g. pressure
``````

Pressure affects the solubility of

``````-->  a. gases.

b. solids.

c. liquids.

d. all of the above
``````

solution with a high concentration of solute

``````a. solubility

b. saturated solution

c. concentration

d. dilute solution

e. unsaturated solution

-->  f. concentrated solution

g. pressure
``````

Carbon dioxide is least soluble in ocean water

``````-->  a. at the equator.

b. near the South Pole.

c. in the Arctic Ocean.

d. in the North Atlantic Ocean.
``````

How much solute is there in a 100-gram solution if the concentration is 5 percent?

``````-->  a. 5 grams

b. 20 grams

c. 95 grams

d. 100 grams
``````

factor that affects the solubility of gases

``````a. solubility

b. saturated solution

c. concentration

d. dilute solution

e. unsaturated solution

f. concentrated solution

-->  g. pressure
``````

amount of solute in a given amount of solution

``````a. solubility

b. saturated solution

-->  c. concentration

d. dilute solution

e. unsaturated solution

f. concentrated solution

g. pressure
``````

Baking soda has a solubility of 96 gram per liter of 20 C water. How much baking soda must you add to 2 liters of water at this temperature to make a saturated solution?

``````a. 48 grams

b. 96 grams

-->  c. 192 grams

d. 1000 grams
``````

solution that contains as much solute as can dissolve at a given temperature

``````a. solubility

-->  b. saturated solution

c. concentration

d. dilute solution

e. unsaturated solution

f. concentrated solution

g. pressure
``````

amount of solute that can dissolve in a given amount of solvent at a given temperature

``````-->  a. solubility

b. saturated solution

c. concentration

d. dilute solution

e. unsaturated solution

f. concentrated solution

g. pressure
``````

Which of the following substances is most soluble in water?

``````a. table salt.

b. baking soda.

c. Epsom salt.

-->  d. table sugar.
``````

Which statement is true of any saturated solution at a given temperature?

``````-->  a. No more solute will dissolve in the solution.

b. You can dissolve more solute if you stir the solution.

c. One liter of the solution contains 2000 grams of solute.

d. Adding more solute will increase the saturation of the solution.
``````

Factors that affect the solubility of a solid solute in a given liquid solvent include

``````a. size of container.

-->  b. temperature.

c. pressure.

d. two of the above
``````

Epsom salt is more soluble in water than is sugar.

``````a. true

-->  b. false
``````

Soda fizzes as you open the can because

``````a. carbon dioxide evaporates from the sod

-->  b. pressure decreases on carbon dioxide in the soda.

c. the soda suddenly dissolves more carbon dioxide.

d. the soda gets warmer and releases carbon dioxide.
``````

You can increase the solubility of a solute by adding more of it to a solution.

``````a. true

-->  b. false
``````

What is the concentration of a 300-gram saltwater solution that contains 6 grams of salt?

``````a. 1%

-->  b. 2%

c. 5%

d. 6%
``````

The solubility of Epsom salt in water is 250 g per 1 L of water at 20 C. What mass of Epsom salt will dissolve in 500 mL of 20 C water?

``````a. 115 g

-->  b. 125 g

c. 225 g

d. 255 g
``````

You can dissolve more of a liquid solute if you heat the solution.

``````-->  a. true

b. false
``````

Based on the solubility of Epsom salt in question 6, what mass of Epsom salt will dissolve in 1 L of water at 30 C.

``````a. less than 250 g

b. exactly 250 g

-->  c. more than 250 g

d. it depends on the pressure
``````

Concentration is the amount of solute in a given amount of solvent.

``````a. true

-->  b. false
``````

A saturated solution always has a very high concentration.

``````a. true

-->  b. false
``````

Solubility increases if you stir a solute into a solution.

``````a. true

-->  b. false
``````

All solutes have the same solubility in a given solvent.

``````a. true

-->  b. false
``````

There is a limit on the amount of solute that can dissolve in a given solvent.

``````-->  a. true

b. false
``````

You can dissolve additional solute in an unsaturated solution.

``````-->  a. true

b. false
``````

Both temperature and pressure affect the solubility of any solute.

``````a. true

-->  b. false
``````

Less oxygen can dissolve in warm water than in cold water.

``````-->  a. true

b. false
``````

A solute with greater solubility can form a more concentrated solution than a solute with lesser solubility.

``````-->  a. true

b. false
``````

The concentration of a solution is the amount of solvent in a given amount of solvent.

``````a. true

-->  b. false
``````

The concentration of a solution is usually expressed as a percent.

``````-->  a. true

b. false
``````

Heating a liquid solute increases its solubility.

``````-->  a. true

b. false
``````

## diagram questions

No diagram questions associated with this lesson