Define a saturated solution.
Use the terms solvent and solute.


A solution is saturated when the solvent (usually water) has dissolved the maximum amount of solute. 

If you want to dissolve a greater amount of salt in a solution, what should you do with the temperature? 

Since salt is an ionic compound, then raising the temperature will allow you to dissolve a greater amount of salt.


What is the solubility of KNO_{3} at 35 °C? 

According to the solubility curve, the solubility is
55 g of KNO_{3} in 100 g H_{2}O
at 35 °C.


With increasing temperature, the solubility of a gas (increases/decreases). 


You have 80 grams of 20 ºC water, and 50 grams of KNO_{3}.
Explain how you would make a saturated solution of KNO_{3} with these materials.


Since the solubility of KNO_{3} at this temperature is about 30 grams in 100 grams of water, which is equivalent to 24 grams of KNO_{3} in 80 grams of water, you would measure out 24 grams of KNO_{3 }and dissolve it in the 80 grams of water.


A saturated solution of NH_{4}Cl made with 100 grams of water, is initially at 90 ºC.
You then let the solution cool to 5 ºC.
How many grams of NH_{4}Cl will precipitate out of solution at 5 ºC?


70 g – 30 g = 40 g
40 grams will precipitate out.


You think you are in possession of a saturated solution of NaCl. But you want to be sure.
Explain how you could use a single crystal of NaCl to find out.


Add the single crystal to the solution. If the crystal does not dissolve, then the solution was saturated.
If the crystal does dissolve, then the solution was unsaturated.


Calculate the pph concentration of a saturated solution of potassium iodide at 20 ºC. 

According to the solubility curve, the solubility at 20 ºC is about 145 g KI/100 g H_{2}O.
So, the pph concentration is calculated by dividing the mass of the solute by the total mass of the solution.
145 = x solve for x, get 59 pph
245 100


A sample of river water is found to have a lead(IV) concentration of 18 ppm.
How many grams of lead(IV) ion are in a 450 kg sample of this river water?


18 ppm means 18 kg of lead(IV) ion dissolved in 1,000,000 kg of river water sample. So set up the following ratio:
18 = x solve for x, get 0.0081 kg.
1,000,000 450 kg
But since they ask for the grams, 0.0081 kg is 8.1 grams.


If 14 grams of sodium nitrate is dissolved in 75 grams of water, calculate the pph concentration. 

14 = x solve for x, get 15.7 pph.
89 100


A solution of 80 grams of NH_{3} dissolved in 200 grams of water at 15 ºC is (saturated/unsaturated/supersaturated). 

Unsaturated.
At 15 ºC, the solubility of NH_{3} is 60 grams per 100 grams of water, which is equivalent to 120 grams per 200 grams of water.
Since only 80 grams of NH_{3} are dissolved, then the solution is unsaturated.


A chemist dissolves 30 grams of potassium chloride in 100 grams of water at 50 ºC. The solution is unsaturated.
How many more grams of solute need to be added to make the solution saturated?



A Na^{+} solution has a concentration of 8 pph. Describe how mnay grams of solute and solvent are in a 100 gram sample of this solution. 

8 pph means that 8 grams of sodium ion are dissolved in 92 grams of water. 

A solution is classified as a base if the concentration of which ion (H^{+} or OH^{–}) is greater?


OH^{–} concentration is greater. 



A solution having a pH=6 is classified as a(n)
(acid / base).



How does the concentration of H^{+} in solutions with pH values of 4 and 7 compare? 

Since the pH difference is 3, the concentration difference is
10 x 10 x 10 = 1000 times difference in concentration.


Give two examples of heavy metals. 


If an unknown clear liquid is miscible with water, the unknown liquid is classified as (polar/nonpolar). 


Salt dissolves in water, but not in acetone.
Therefore acetone is (polar/nonpolar).



Explain why water is a polar molecule. 

Water is a polar molecule because the two bonds in water have unequallyshared electrons.
As a result, the molecule has partial charges on it.


Draw two water molecules, showing the partial charges on each molecule.
Then show a hydrogen bond between the two molecules.



Which solute – NaNO_{3}, NH_{4}Cl or or NaCl – has a greater temperature dependence on its solubility? 

NaNO_{3}. This solute has the largest slope of the three solubility lines. 

Clove oil is a dark brown, denserthanwater nonpolar liquid.
If you mix water, CuSO_{4} and clove oil together, what would the resulting mixture look like? Discuss colors.


The CuSO_{4} would dissolve in the water, and the clove oil and water/CuCO_{4} solution would make separate layers, with the clove oil on the bottom.
So the top layer would be a clear or slightly blue solution, and the bottom layer would be dark brown.

