Unit 4 Practice Problems
Solubility
1.
What is a solution? Give specific examples of three different types of solutions: solid dissolved in a liquid, gas dissolved in a
liquid, and gas dissolved in a gas.
2.
Discuss how an ionic solute such as NaCl dissolves in water. How are the strong ionic bonds in the solid overcome to permit
the solid to dissolve?
3.
Explain how a polar covalent molecule such as a simple sugar (C6H12O6) can dissolve in water?
4.
What determines whether a solute will be soluble in a given solvent?
5.
When KNO3 is added to water, the temperature of the solution decreases. Circle the correct option.
a) lattice energy is (greater/less) than hydration energy.
b) KNO3 is more soluble in (warm/cold) water.
6.
Predict (circle) which solvent will dissolve more of the given solute:
a) NaCl in methanol (CH3OH) or in 1-propanol (CH3CH2CH2OH)
b) Ethylene glycol (HOCH2CH2OH) in hexane (C6H14) or in water.
c) Diethyl ether (CH3CH2OCH2CH3) in water or in ethanol (CH3CH2OH)
7.
Will sugar, C6H12O6 a polar covalent molecule, dissolve in nail polish remover, a nonpolar solvent? Explain.
8.
Will oil, a long carbon chain hydrocarbon (nonpolar) dissolve in water? Explain.
9.
Hydrogen chloride (HCl) gas is much more soluble than propane (C 3H8) in water, even though HCl has a lower boiling point.
Explain.
10. What is the strongest type of intermolecular force between solute and solvent in each solution?
a) CH3OH(l) in CCl4(l)
__________________________
b) CH3Cl(g) in CH3OCH3(g) __________________________
c) NaCl(s) in H2O(l)
__________________________
11. How does the solubility of a gas in liquid depend on temperature? How does this temperature dependence affect the amount
of oxygen available to aquatic animals?
12. How does the solubility of a gas depend on pressure? How does this pressure dependence account for the bubbling that
occurs upon opening a can of soda?
13. Fill in the chart below with either increases, decreases, or remains the same for changing the following factors on the
SOLUBILITY of the solute in water:
Solute
CO2(g)
NaCl(s)
increasing temp
decreasing temp
increasing pressure
decreasing pressure
14. What is the concentration of CO2 (k = 3.1 x 10-2 mol/L•atm) that is bottled with a partial pressure of 4.0 atm?
15. What is the concentration of N2 (k = 6.8 x 10-4 mol/L-atm) in a diver's blood if he breaths air at 2.5 atm that is 78 % N 2.
16. Household vinegar (CH3COOH(aq)) is labeled as 5.00% by weight. It has a density of 1.01 g/mL. Fill in the chart.
mass (grams)
moles (mol)
volume (L)
solute
solvent
solution
17. A solution is made up of 123 g NaOH and 289 g water. The total volume is 300. mL. Determine
mole NaOH
mole H2O
mass %
mole fraction
molarity
PPM
18. Using the solubility graph, determine if the following solutions are saturated, unsaturated or supersaturated. If they are
anything but saturated, list two things you can do to make them saturated (include numbers).
Solution (in 100g H2O)
40 g of KClO3 at 50oC
110 g NaNO3 at 45oC
70 g KNO3 at 60oC
70 g NH4Cl at 70oC
Sat, Unsat, Supersat
+/- how many °C to make
saturated?
+/- how many g to
make saturated?
19. Determine the density of 12.0 M HCl. It is 37.0 % HCl by mass.
a.
What is the mass of HCl in one liter of solution?
b.
What is the mass of one liter of solution?
c.
What is the density of 12 M HCl in g/mL?
20. How would you prepare 250. mL of a 0.127 M Ca(OH)2
a. from powder Ca(OH)2?
b. from 1.00 M Ca(OH)2?
21. You are asked to make 100. mL of a 0.125 M NaHCO3 solution.
a. What mass of powder NaHCO3 would you need?
b. What volume of 3.00 M NaHCO3 would you need?
22. How many liters of 0.487 M NaOH is needed to make 0.100 L of a 0.200 M solution?
23. What is the molarity of a solution when water is added to 25.0 mL of 0.400 M HNO3 to make 75.0 mL?
24. What is the molarity of a solution that contains 73.2 g of NH4NO3 in 0.835 L of solution?
25. Consider a 0.250 M solution of Na2SO4.
a. What volume contains 0.700 moles Na2SO4?
b. How many grams of Na2SO4 are in 0.800 L of solution?
c. What volume contains 157 g of Na2SO4?