11U -- Unit 2--Quantities—Practice Note: this sample test does not reflect length, weight and
necessarily every topic and type of question that will be on the unit test. It should not be your
only study tool, but rather used in conjunction with class notes, textbook and other resources.
Multiple Choice
Identify the choice that best completes the statement or answers the question.
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1. Tin and oxygen can combine to form two compounds of different combining proportions. Resulting formulas
of these compounds include
a. Sn2O and SnO2
d. SnO and SnO3
b. SnO and SnO2
e. SnO2 and SnO4
c. SnO4 and SnO
2. A new element, dmytrium, has two isotopes, Dm-350 and Dm-375. The composition of dmytrium is 62.0%
Dm-350 and 38.0% Dm-375 by mass. The relative atomic mass of this new element is
a. 351 u
d. 366 u
b. 354 u
e. 360 u
c. 357 u
3. The number of moles of H in three moles of copper(II) sulfate pentahydrate, CuSO4.5H2O, is
a. 2
d. 30
b. 6
e. 50
c. 10
4. The number of molecules of hydrogen peroxide found in 3.15 mol of H2O2 is
a. 3 molecules
d. 7.60  1023 molecules
24
b. 1.90  10 molecules
e. 1.52  1024 molecules
23
c. 3.80  10 molecules
5. The molar mass of a sample of atoms of an element was found to be 107.9 g/mol. This element is likely
a. silver
d. oxygen
b. copper
e. lead
c. magnesium
6. The number of moles of molecules in 71.6 g of methane, CH4, (molar mass = 16.0 g/mol) is
a. 0.22 mol
d. 9.77 mol
b. 4.48 mol
e. 1145 mol
c. 8.77 mol
7. The total number of atoms in 3.75 mol of ammonium nitrate, NH4NO3, is
a. 2.03  1025 atoms
d. 2.58  1025 atoms
25
b. 1.58  10 atoms
e. 3.58  1025 atoms
c. 1.12  1025 atoms
8. The mass found in 0.10 mol of KHC4H4O6 is
a. 4.6 g
d. 37.6 g
b. 19 g
e. 55.8 g
c. 23.7 g
9. A patient takes two 50.0-mg tablets on a daily basis to help regulate a heart condition. If the daily dosage is
equivalent to 5.0  10–4 moles, then its molar mass is
a. 200 g/mol
d. 50 g/mol
b. 100 g/mol
e. 800 g/mol
c. 400 g/mol
2
____ 10. Converting 153.0 g of Mg(CN)2 into moles yields approximately
a. 0.98 mol
d. 3.06 mol
b. 1.49 mol
e. 2.00 mol
c. 2.53 mol
____ 11. A compound containing carbon, hydrogen, and chlorine is composed of 49.0% carbon and 2.74% hydrogen
by mass; the remainder is chlorine. The empirical formula of the compound is
a. CHCl
d. C2H3Cl
b. C3H2Cl
e. C2H3Cl2
c. C2H2Cl
____ 12. Upon analysis in the lab, a compound is found to consist of 2.2% hydrogen, 26.7% carbon, and 71.1%
oxygen. The empirical formula for this compound is
a. H2C2O4
d. HCO2
b. HCO
e. HC2O2
c. HC2O
____ 13. If the molar mass of a hydrocarbon is 26.0 g/mol, and its empirical formula is CH, its molecular formula is
a. CH
d. C4H4
b. C2H2
e. C5H5
c. C3H3
____ 14. Identify the career where it is important to be able to analyze unknown substances and determine the chemical
content of these substances.
a. forensic lab technician
b. water purification technician
c. gemologist
d. metallurgy technician
e. all of the above
____ 15. Which one of the following statements is a quantitative observation?
a. The freezing point of the clear and colourless solution was –40.5C.
b. The reactant demonstrated a high degree of viscosity.
c. The overall reaction was exothermic.
d. The product was yellow in colour.
e. A brown-coloured gas evolved from the test tube.
____ 16. Which of the following scenarios does NOT represent a quantitative analysis?
a. A chemist tests a sample of water for the presence of chloride ions.
b. A police officer uses a breathalyzer to measure the amount of alcohol in exhaled air.
c. A lifeguard tests a sample of water to see how much disinfectant is present in the water.
d. A sample of soil from a farm is tested for dangerously high levels of bacterial content.
e. all of the above
____ 17. The skeleton equation representing the neutralization of aluminum hydroxide with hydrochloric acid is
Al(OH)3 + HCl
AlCl3 + H2O. The coefficient of HCl in the balanced equation is
a. 1
d. 7
b. 3
e. 9
c. 6
____ 18. Consider the following nuclear equation:
This equation is classified as
a. radioactive decay
b. artificial transmutation
c. fission
+
+
d. fusion
e. none of the above
3
____ 19. Consider the following equation:
+
+ _____
The missing nuclear particle required to complete this balanced nuclear equation is
a.
d.
b.
e.
c.
____ 20. Consider the following equation:
+
_____ +
To complete this balanced nuclear equation, the missing nuclear particle would be:
a.
d.
b.
e.
c.
____ 21. The limiting reagent of a chemical reaction is
a. the reactant of a chemical process that is not consumed completely
b. the product of a chemical process that is consumed completely
c. the product of a chemical process that is not consumed completely
d. the reactant of a chemical process that is consumed completely
e. none of the above
____ 22. The reaction between hydrazine and hydrogen peroxide is shown in the balanced chemical equation N2H4 +
7 H2O2
2 HNO3 + 8 H2O. If 4.0 moles of hydrazine were used up in the reaction, the number of moles of
water produced would total
a. 2
d. 16
b. 7
e. 32
c. 8
____ 23. Ethane burns in oxygen to produce carbon dioxide and water. The balanced chemical equation is 2C2H6 +
7O2
4CO2 + 6H2O. The molar ratio between the ethane and water is
a. 1:2
d. 7:4
b. 2:7
e. 4:7
c. 1:3
____ 24. When calcium is allowed to react with nitrogen, N2, calcium nitride is formed, as shown in the following
balanced chemical equation: 3Ca + N2
Ca3N2
If 24.0 g of calcium and 12.0 g of nitrogen are available for this reaction, the limiting reagent will be
a. calcium
b. nitrogen
c. calcium nitride
d. both calcium and nitrogen will be consumed completely
e. cannot be determined
____ 25. Consider the following balanced equation: Al(OH)3 + 3HCl
AlCl3 + 3H2O
Determine the number of grams of aluminum chloride, AlCl3, that are formed when 25.0 g of aluminum
hydroxide reacts with 50.0 g of hydrochloric acid.
a. 19.0 g
d. 36.1 g
b. 24.1 g
e. 42.7 g
c. 33.1 g
Short Answer
26. Determine the number of carbon atoms found in 2.50 mol of methane, CH4.
4
27. Calculate the number of moles found in 168.0 g of iron(II) oxide.
28. Calculate the number of empirical formula units of NaC4H2O2 found in a compound with a molecular mass of
210.0 u.
29. Balance the following equation by inspection: C10H22 + O2
CO2 + H2O
30. Briefly state why the construction of a nuclear power station is so costly.
Problem
31. Convert a mass of 1.2 kg of iron(III) chloride to an amount in moles.
32. Calculate the mass found in 1.27 mol of sodium phosphate.
33. Calculate the number of sodium ions in 0.949 mol of sodium chloride.
34. Calculate the number of hydrogen acetate (HC2H3O2) molecules present in 0.775 kg of the substance.
35. Calculate the mass of 12 ammonia (NH3) molecules.
36. Titanium dioxide, TiO2, can be used as an abrasive in toothpaste. Calculate the percentage of titanium, by
mass, in titanium dioxide.
37. What is the empirical formula of a compound whose percentage composition is found to be 2.20% hydrogen,
26.7% carbon, and 71.1% oxygen?
38. What is the empirical formula of a compound whose percentage composition is found to be 69.9% iron and
30.1% oxygen?
39. Consider the following balanced equation: LiAlH4 + 4H2O
LiOH + Al(OH)3 + 4H2
How many grams of Al(OH)3 will be produced from the hydration of 4.20 g of LiAlH4?
40. Consider the following balanced equation: 2Li3PO4 + 3Zn(NO3)2
Zn3(PO4)2 + 6LiNO3
Determine the mass of lithium nitrate that will be produced when 415.0 g of zinc nitrate is combined with
excess lithium phosphate.
41. Consider the following combustion reaction: C3H8 + 5O2
3CO2 + 4H2O
Determine the mass of carbon dioxide that will be formed when 131.0 g of propane, C3H8, is reacted with
excess oxygen.
42. Consider the following combustion reaction: CH4 + 2O2
CO2 + 2H2O
Determine the mass of oxygen that will react completely with 18.3 g of methane, CH4.
43. Consider the following reaction: CH4 + 2O2
CO2 + 2H2O
How many grams of carbon dioxide will be produced when 15.0 g of CH4 and 30.0 g of O2 are available for
reaction?
44. Consider the following balanced equation: Mg(OH)2 + 2HCl
MgCl2 + 2H2O
Determine the mass of magnesium chloride produced when 5.91 g of Mg(OH)2 is combined with 9.98 g of
HCl.
45. Consider the following balanced equation: 2Al + 3 Br2
2AlBr3
Determine the mass of aluminum bromide produced when 31.0 g of aluminum is combined with 97.5 g of
bromine.
5
Stoich unit-practice
Answer Section
MULTIPLE CHOICE
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
B
E
D
B
A
B
A
B
A
E
B
D
B
E
A
A
B
B
A
E
D
E
C
A
E
SHORT ANSWER
26.
Since there is one carbon atom in each methane molecule, there are 1.51  1024 atoms of carbon present.
27.
6
A mass of 168.0 g of iron(II) oxide is equivalent to 2.338 mol.
28.
There are two empirical formula units in this compound.
29. 2C10H22 + 31O2
20CO2 + 22H2O
30. -The construction of a nuclear power station is far more complex than a coal-fired power plant.
-The cost of incorporating safety features into these stations also carries an enormous expense.
PROBLEM
31. m = 1.2 kg
M = (1  55.8) + (3  35.5)
M = 162.3 g/mol
A mass of 1.2 kg of iron(III) chloride is equivalent to 7.4 mol of iron(III) chloride.
32. n = 1.27 mol
M = 164.0 g/mol
The mass of 1.27 mol of Na3PO4 is 208 g.
33. nNaCl = 0.949 mol
There are 5.71  1023 formula units in 0.949 mol of sodium chloride. Since the ratio of cation to anion in NaCl
is 1:1, there are 5.71  1023 sodium ions in 0.949 mol of sodium chloride.
34.
7
m = 775.0 g
There are 7.78  1024 molecules of hydrogen acetate in 0.775 kg of the substance.
35.
Note: There are 6.02  1023 molecules of ammonia in one mole of ammonia.
The mass of one ammonia molecule is 2.83  10–23 g.
The mass of 12 ammonia molecules is 3.40  10–22 g.
36. mTi = 47.88 u  1 atom = 47.88 u
mO = 16.00 u  2 atoms = 32.00 u
mtotal = 79.90 u
The percentage composition of titanium in TiO2 is 59.94%.
37.
mH = 2.20%  100.0 g H = 2.20 g
mC = 26.7%  100.0 g C = 26.7 g
mO = 71.1%  100.0 g O = 71.1 g
MH = 1.01 g/mol
MC = 12.01 g/mol
MO = 16.00 g/mol
8
The molar ratio for H:C:O is 2.18:2.22:4.44. Dividing by 2.18 to obtain the lowest ratio, we obtain the molar
ratio of H:C:O to be 1:1:2.
The empirical formula of the compound is HCO2.
38.
mFe = 69.9%  100.0 g Fe = 69.9 g
mO = 30.1%  100.0 g O = 30.1 g
MFe = 55.8 g/mol
MO = 16.00 g/mol
The molar ratio for Fe:O is 1.25:1.88. Dividing by 1.25 to obtain the lowest ratio, we obtain the molar ratio of
Fe:O to be 1:1.5. Multiplying this ratio by 2, we obtain a final 2:3 ratio.
The empirical formula of the compound is Fe2O3.
39.
mole ratio:
LiAlH4:Al(OH)3 = 1:1
The mass of aluminum hydroxide that can be obtained is 8.63 g.
40.
mole ratio:
Zn(NO3)2:LiNO3 = 1:2
9
The mass of lithium nitrate that will be produced is 302.1 g.
41.
mole ratio:
C3H8:CO2 = 1:3
The mass of carbon dioxide that will be produced is 393.0 g.
42.
mole ratio:
CH4:O2 = 1:2
The mass of oxygen required is 73.0 g.
43. We can determine the number of moles of oxygen gas needed to react completely with 15.0 g of methane.
10
mole ratio:
CH4:O2 = 1:2
There is not enough O2 available for 15.0 g of methane to react completely. The oxygen gas is the limiting
reagent.
mole ratio:
O2:CO2 = 2:1
The mass of carbon dioxide produced is 20.6 g.
44. We can determine the number of moles of HCl needed to react completely with 5.91 g of magnesium
hydroxide.
mole ratio:
Mg(OH)2:HCl = 1:2
More HCl is available than is required, therefore, HCl is in excess. The magnesium hydroxide is the limiting
reagent.
11
mole ratio:
Mg(OH)2:MgCl2 = 1:1
The mass of magnesium chloride produced is 9.62 g.
45. We can determine the number of moles of bromine needed to react completely with 31.00 g of aluminum
mole ratio:
Al:Br2 = 2:3
There is not enough Br2 available for 31.0 g of aluminum to react completely. The bromine is the limiting
reagent.
mole ratio:
Br2:AlBr3 = 3:2
The mass of aluminum bromide produced is 108.5 grams.