Chapter 3 Practice Test

Question 1

Which one of the following chemical equations is balanced?

Answer 1

SO3 + H2O → H2SO4

Question 2

Which of the following represents a balanced chemical equation for the word equation below?
iron(II) sulfide + hydrochloric acid → iron(II) chloride + hydrogen sulfide

Answer 2

FeS + 2HCl → FeCl2 + H2S

Question 3

In the following balanced chemical equation,

2Al(OH)3 + 3H2 SO4 → Al2(SO4 )3 + 6H2 O 

what is the ratio of water molecules produced per molecule of sulfuric acid in the reaction?

Answer 3

2 molecules of water per molecule of sulfuric acid

Question 4

Calcium carbonate reacts with hydrochloric acid to produce calcium chloride, water, and carbon dioxide. Which of the following balanced chemical equations represents this reaction?

Answer 4

CaCO3 + 2HCl → CaCl2 + H2O + CO2

Question 5

Balance the following chemical reaction:

NaHCO3 → Na2CO3 + H2O + CO2

Answer 5

2NaHCO3 → Na2CO3 + H2O + CO2

Question 6

Balance the following chemical reaction for the decomposition of nitroglycerin to form many moles of different gases.

C3H5N3O9 → N2 + CO2 + H2O + O2

Answer 6

4C3H5N3O9 → 6N2 + 12CO2 + 10H2O + O2

Question 7

How many molecules of carbon dioxide are found in 2.50 moles of carbon dioxide?

Answer 7

1.51 × 10^24 molecules

Question 8

How many atoms of hydrogen, sulfur, and oxygen are in 1.00 mol of H2SO4?

Answer 8

1. 20 × 10^24 hydrogen;
2. 02 × 10^23 sulfur;
3. 41 × 10^24 oxygen

Question 9

How many atoms of uranium are there in 7.11 millimoles of this substance?

Answer 9

4.28 × 10^21 atoms

Question 10

What mass does 0.876 moles of hydrogen peroxide (H2O2 ) represent?

Answer 10

29.8 grams

Question 11

In the portion of the periodic table shown, what does the number 12.0107 represent?

Answer 11

molar mass

Question 12

What is the molar mass of ethanol (C2H6O)?

Answer 12

46.064 grams / mole

Question 13

When the mass percent of each element making up an unknown compound is given, what other information is needed to determine the empirical formula?

Answer 13

the molar mass of each element

Question 14

The mineral zircon contains the following elements in the mass proportions indicated:

49. 8% Zr
15. 3% Si
34. 9% O

What is the empirical formula of zircon?

Answer 14

ZrSiO4

Question 15

What is the minimum information necessary in order to determine the molecular formula of an unknown compound?

Answer 15

the empirical formula plus the molecular weight of the compound

Question 16

How many grams of hydrazine, N2H4, are produced from the reaction of 5.0 moles of N2 with an excess of H2, as shown in the following equation:

2H2(g) + N2(g) → N2H4(g)

Answer 16

160 g

Question 17

Elemental tungsten (W) can be produced by the following reaction: WO3(s) + 3H2(g) -> W(s) + 3H2O(l) How many moles of tungsten form in the reaction of 0.0207 moles of WO3?

Answer 17

0.0207 mol

Question 18

Using the following balanced chemical equation, calculate the number of grams of aluminum bromide (AlBr3 ) formed during the reaction of 1.50 moles of HBr in the presence of excess aluminum hydroxide. 3HBr(aq) + AL(OH)3(aq) -> ALBr3(aq) + 3H2O(l)

Answer 18

133 grams

Question 19

In the reaction shown

2Al + 6HCl → 2AlCl3 + 3H2 

How many moles of hydrogen gas are produced from 4.8 mol of HCl and 2.2 mol of Al?

Answer 19

2.4 mol

Question 20

In the following reaction, what is the limiting reactant if the reaction begins with 7.4 g Ca(OH)2 and 10.4 g H3PO4?

3Ca(OH)2 + 2H3PO4 → Ca3(PO4 )2 + 6H2O

Answer 20

Ca(OH)2

Question 21

20.30 grams of zinc sulfide (ZnS) is burned in 36.46 grams of oxygen gas to form zinc oxide (ZnO) and sulfur dioxide gas (SO2 ), according to the following balanced chemical equation:
2ZnS + 3O2 → 2ZnO + 2SO2
What is the limiting reagent?

Answer 21

ZnS

Question 22

What mass of ozone could be produced from a car’s exhaust if 4.00 g NO2 react in an excess of oxygen?

NO2(g) + O2(g) → NO(g) + O3(g)

Answer 22

4.17 g O3

Question 23

If you react 2.0 g AgNO3 and 2.5 g Na2SO4, what is the percent yield if the actual yield is 1.6 g Ag2SO4?

2AgNO3 + Na2SO4 → Ag2SO4 + 2NaNO3

Answer 23

87%

Question 24

What is the percent oxygen in carbon dioxide by mass?

Answer 24

72.73%

Question 25

Which of the following compounds has the greatest mass percent of carbon?

Answer 25

ethanol, C2H5OH