Unit One C1-C2 homework

1.A. What mass of potassium nitrate (KNO3) will dissolve in 100g water at 60 degrees C?

105grams

B.What mass of potassium chloride will dissolve in 100 g water at the same 60 degree C temperature?

45 grams

2. a. You dissolve 25 g potassium nitrate in 100g water at 30 degrees C, producing an unsaturated solution. How much more potassium nitrate must be added to form a saturated solution at 30 degrees C?

10g

B. what is the minimum mass of 30 degrees C water needed to dissolve 20 g potassium nitrate

45grams

3. A. A supersaturated solution of potassium nitrate is formed by adding 150g KNO3 to 100 g water, heating until the solute completely dissolves, and then cooling the solution to 55 degrees C. If the solution is agitated, how much potassium nitrate will precipitate.

50g

Page 82 1-8

1. Explain why three teaspoons of sugar will completely dissolve in a serving of hot tea, but will not dissolve in an equally sized serving of iced tea.

Because of solubility. At a high temperature a larger amount of solids dissolve than at a lower temperature

2.What is the maximum mass of potassium chloride(KCL) that will dissolve in 100.0g water at 70 degreesC.

131g

3. If the solubility of sugar in water is 2.0 g/mL at room temperature, what is the maximum mass of sugar that will dissolve.

a. 100.0 mL water?

200 g/mL

b. 355 mL water?

710 g/mL

c. 946 mL water?

9182 g/mL

4. Rank the substances in Figure 1.33 from most soluble to least soluble at 

a. 20 degrees C

KNO₃, KCI, NaCl

B. 80 degrees C

KNO₃, KCI, NaCl

5. Distinguish between the term saturated and unsaturated

Saturated means that the liquid can't dissolve the particles anymore, and that there are precipitates at the bottom of the liquid.

unsaturation is when the solution has less solutes than the amount of solvents it can normal hold at that temperature

6.Using the graph on page 54, answer these questions about the solubility of potassium nitrate, KNO_3,

_{a. What is the maximum mass of KNO3 can dissolve in 100g water if the water temperature is 20 degrees C?}

_30g

_{B. A 30 degrees, 55 g KNO3 is dissolved into 100 g water. Is this solution saturated, unsaturated, or supersaturated?}

_{Supersaturated}

_{C. A saturated solution of KNO3 is formed in 100 g water at 75 degrees C. If some solute precipitates as the saturated solution cools to 40 degrees C, what mass of solid KNO3 should form.}

_80g

_{7. You are given a solution of KNO3 of unknown concentration. What will happen when you add crystal of KNO3 if the solution is}

_{a.Unsaturated?}

_{Nothing would happen, the crystals would dissolve into the water}

_{B. saturated}

_{All the crystals would go down to the bottom}

_{C. Supersaturated}

_{The crystals would sink down to the bottom}

_{8. A 35-g sample of ethanol is dissolved into a 115g water. What is the percent concentration of the ethanol, expressed as a percent ethanal by mass?}

_35%