Regents Chemistry
2013-2014
Unit Test Review: Solutions
Questions 1-7 are molarity problems
Molarity (M) = moles of solute
liters of solution
1. How many moles of solute are contained in 200ml of a 1M solution?
1M =
x
0.2L
x = 0.2 moles
2. How many moles of solute would 3 liters of a 2-molar solution contain?
M = moles
Liter
2M =
x
3L
x = 6moles
3. What is the molarity of a solution of NaOH if 2 liters of the solution contains
4 moles of NaOH?
M = 4 moles
2 liters
= 2M
4. A mass of 49.0g of H2SO4 is dissolved in water to prepare a 0.50M solution. What
is the volume of the solution in liters?
49g
= 0.5 mol H2SO4
98g/mol
M = moles
0.50M = 0.5 mol
liter
x
x = 1liter
5. How many grams of CaCO3 are needed to prepare 400.0ml of a 0.6M solution?
M = moles
liter
0.6M =
x
0.4L
x = 0.24mol
0.24mol
x 100g/mol
24g
6. How many moles of NaOH are in 200.0ml of a 0.250M NaOH solution?
M = moles
liter
0.250M =
x
0.200L
x = 0.050moles
7. What is the molarity of a solution that contains 40.0g of NaOH on 0.50 liters of solution?
40.0g
= 1 mole NaOH
M = moles = 1mole = 2M
40g/mol
Liter
0.50L
Questions 8-11 are dilution problems (molarityinitial soln)(volumeinitial soln) = (molarityfinal soln)(volume final soln)
8. How would you prepare 240.0ml of a 2.0M solution of HCl if you started with
concentrated HCl (12M)?
(240ml)(2.0M) = (x)(12M)
40mL = x
9. If 20.0ml of a 1.0M solution of HCl is exactly neutralized by 40.0ml of NaOH,
what is the molarity of the NaOH solution?
(20.0ml)(1.0M) = (40.0ml)(x)
0.5M = x
10. How many milliliters of 12.0M HCl(aq) must be diluted with water to make exactly
500ml of 3.0M HCl?
(x)(12.0M) = (500ml)(3.0M)
x = 125ml
11. A 250.0ml of 0.936M NaOH solution is diluted to 750.0ml. Find the molarity of the diluted
solution.
(250.0ml)(0.936M) = (750.0ml)(x)
0.312M = x
Questions 12-19 are concentration problems: PERCENT (by mass/volume) AND ppm.
12. A solution is made by dissolving 25.0g of NH3 in 100.0g of water at 25°C. What is the
percent by mass of NH3 in this solution? [round answer to whole #]
25.0g
125.0g
x
100 = 20%
13. Find the percent by volume of toluene in a solution formed from 5.0ml of toluene
and 95.0ml of benzene. [round answer to whole #]
5ml x 100 = 5%
100ml
14. If 175g of NaCl is dissolved in 1.5 liters of water, what is the percent by mass of
NaCl in the solution? [round answer to 2 decimals]
1.5L = 1500ml = 1500g water
175g x 100 = 10.45%
1675g
15. What is the percent by volume of ethanol if 50ml of ethanol is added to 50ml
of water? [round answer to whole #]
50ml x 100 = 50%
100ml
16. Find the concentration in ppm if 0.058g of NaCl is dissolved in 1 liter of water.
[round answer to 1 decimal]
ppm =
0.058g
1,000.058g
x 1,000,000 = 58.0 ppm
17. A substance has a solubility of 350ppm. How many grams of the substance are present in
1.0 liter of a saturated solution? [round answer to 2 decimals]
350 ppm =
x
1,000g
x 1,000,000
x = 0.35g
18. How many grams of C6H12O6 are needed to be dissolved in water to make 100.0g of a
250ppm solution? [round answer to 2 decimals]
250 ppm =
x
100.0g
x 1,000,000
x = 0.025g
19. What is the concentration expressed in parts per million of a solution containing 15.0g of
KNO3 in 65.0g of H2O? [round answer to whole #]
ppm =
15.0g
80.0g
x 1,000,000 = 187,500 ppm
Questions 20-21 are concentration problems dealing with molarity.
SHOW ALL WORK AND CIRCLE YOUR FINAL ANSWER!!
20. How many grams of KI are needed to prepare 50.0ml of a 4.0M solution?
M = moles
liter
4.0M =
x
0.050L
x = 0.2moles
(0.2 moles)(166g/mol) = 33.2g
21. What is the total number of grams of NaOH needed to make 150ml of a 2.0M
solution?
M = moles
liter
2.0M =
x
0.150L
(0.3moles)(40g/mol) = 12.0g
0.3moles = x
Dissolving equations and particles in solution: identify the following substances as ionic or
covalent; write the dissolving equations for each substance placed in water; identify the number
of moles of dissolved particles (ions or molecules) in solution.
substance
ionic or
covalent
dissolving equation
# mole
in soln
ex
C6H12O6(s) (glucose)
covalent
C6H12O6(s)  C6H12O6(aq)
1 mole
ex
NaCl(s) (table salt)
ionic
NaCl(s)  Na+1(aq) + Cl-1(aq)
2 moles
1
AlBr3(s)
ionic
Al+3(aq) + 3Br-1(aq)
4 moles
2
CO2(g)
covalent
CO2(aq)
1mole
3
CH3OH(l) (methanol)
covalent
CH3OH(aq)
1mole
4
CoCl2(s)
ionic
Co+2(aq) + 2Cl-1(aq)
3 moles
5
SiH4(g) (silane)
covalent
insoluble
6
Ni(NO3)2(s)
ionic
Ni+2(aq) + 2NO3-1(aq)
3 moles
7
C3H6O3(l) (glycerol)
covalent
C3H6O3(aq)
1 mole
8
NH3(g) (ammonia)
covalent
NH4+1(aq) + OH-1(aq)
2 moles
9
C12H22O11(s) (sucrose)
covalent
C12H22O11(aq)
1 mole
10
CuSO4(s)
ionic
Cu+2(aq) + SO4-2(aq)
2 moles
Table J
SR reactions: metals often react with acids to create hydrogen gas
Use table J to determine which of the following metals can undergo a single replacement reaction
with sulfuric acid. Write complete balanced equations for the reactions that can occur.
1. solid cobalt and H2SO4(aq)
Co(s) + H2SO4(aq) 
CoSO4(aq) + H2(g)
2. solid aluminum and H2SO4(aq)
2Al(s) + 3H2SO4(aq)
Al2(SO4)3 + 3H2(g)

3. solid silver and H2SO4(aq)
Ag(s) + H2SO4(aq)

NR
Table F
Double Replacement reactions: predict the products when two aqueous solutions are mixed
Use table F to predict the state of the products that result from the following DR reactions. In
addition to writing the complete balanced equation also write the complete ionic and net ionic
equations as well.
1. K2CrO4(aq) + Ba(NO3)2(aq) 
2KNO3(aq) + Ba(CrO4) (s)
2K+1(aq) + CrO4-2(aq) + Ba+2(aq) + 2NO3-1(aq)  2K+1(aq) + 2NO3-1(aq) + Ba(CrO4) (s)
CrO4-2(aq) + Ba+2(aq) 
2. 3KCl(aq) + Fe(NO3)3(aq)

Ba(CrO4) (s)
3KNO3(aq) + FeCl3(aq)
3K+1(aq) + 3Cl-1(aq) + Fe+3(aq) + 3NO3(aq)  3K+1(aq) + 3NO3(aq) + Fe+3(aq) + 3Cl-1(aq)
Table G
Using Table G answer the following questions.
1. The compound which is least soluble at 20C is KClO3
2. The compound that is most soluble at 10C is KI
3. The compound that is most soluble at 80C is NaNO3
4. The number of grams of sodium chloride needed to saturate 100ml of water at 70C is 38g
5. One hundred ml of a potassium nitrate solution is saturated at 10C. How many additional
grams are needed to saturate the solution at 50C? 60g
6. One hundred ml of a saturated KCl solution at 80C will precipitate 10 grams of salt when
cooled to what temperature? 50g
7. Which two salts have the same degree of solubility at 70C? KNO3 and NaNO3
8. Which salt is most affected by a change in temperature? KNO3
9. The salt with the least increase in solubility in the temperature range between 50C and
75C is NaCl
10. The number of grams of potassium chloride that must be added to 50ml of water to
produce a saturated solution at 40C is 19g
11. A saturated solution of potassium chlorate is made at 20C by dissolving the correct mass
of salt in 100ml of water. When the solution is heated to 80C, how mnay grams of salt
must be added to saturate the solution? 34g
12. At what temperature do potassium nitrate and hydrogen chloride contain the same mass of
solute per 100ml of water? 39C
13. A saturated solution of sodium nitrate is prepared at 55C using 200ml of water. If the
solution is cooled to 35C, how many grams of sodium nitrate will precipitate out of solution?
50g
14. How many more grams of ammonia can be dissolved in 100ml of water at 10C than at 90C?
60g
15. Twenty-five grams of KCl is dissolved in 100ml of water at 10C. Calculate the number of
additional grams of KCl that would be needed to make a saturated solution at 45C? 10g