Deck 2: Chemical Formulas, Chemical Equations, and Reaction Yields

Question 1

What is the relative molecular mass of the compound trinitrotoluene, C₇H₅N₃O₆ (on the ¹²C scale)?

A) 43.03
B) 205.13
C) 215.13
D) 227.13
E) 278.03

Answer 1

227.13

Question 2

Vitamin B₁₂, cyanocobalamin, has the molecular formula, C₆₈H₈₈CoN₁₄O₁₄P. What is the percent mass of cobalt in this compound?

A) 1.02%
B) 4.35%
C) 10.3%
D) 22.3%
E) 23.2%

Answer 2

4.35%

Question 3

For the given unbalanced reaction
X CaO(s) + y H₂O(l) $\rightarrow$ z Ca(OH)₂
The correct stiochiometric coefficients x, y, & z are

A) 1,1,1
B) 1,2,1
C) 2,1,2
D) 2,1,1
E) 1,1,2

Answer 3

1,1,1

Question 4

In fermentation, sucrose, C₁₂H₂₂O₁₁, reacts with water to form ethanol, C₂H₅OH, and carbon dioxide. A balanced chemical equation for this reaction is?

A) C₁₂H₂₂O₁₁(aq) + 3 H₂O(l) $\rightarrow$ 5 C₂H₅OH(aq) + 2 Co₂(g)
B) C₁₂H₂₂O₁₁(aq) + 7 H₂O(l) $\rightarrow$ 2 C₂H₅OH(aq) + 8 Co₂(g)
C) C₁₂H₂₂O₁₁(aq) + 2 H₂O(l) $\rightarrow$ 6 C₂H₅OH(aq) + Co₂(g)
D) C₁₂H₂₂O₁₁(aq) + 2 H₂O(l) $\rightarrow$ 4 C₂H₅OH(aq) + 4 Co₂(g)
E) C₁₂H₂₂O₁₁(aq) + H₂O(l) $\rightarrow$ 4 C₂H₅OH(aq) + 4 Co₂(g)

Question 5

Calcium carbide, CaC₂, reacts with water to produce calcium hydroxide and acetylene gas, C₂H₂.
CaC₂(s) + 2 H₂O(l) $\rightarrow$ Ca(OH)₂(aq) + C₂H₂(g)
How many grams of acetylene can be produced from 30.0 g of calcium carbide?

A) 1.42 g
B) 12.2 g
C) 28.0 g
D) 30.0 g
E) 64.1 g

Question 6

Ammonium perchlorate, NH₄ClO₄, is used with aluminum as rocket fuel.
10 Al(s) + 6 NH₄ClO₄ $\rightarrow$ 4 Al₂O₃ + 2 AlCl₃ + 12 H₂O + 3 N₂
If 100.0 g of aluminum are reacted with 60.0 g of ammonium perchlorate, how many grams of aluminum oxide are produced?

A) 34.71 g
B) 40.00 g
C) 123.8 g
D) 151.1 g
E) 1789 g

Question 7

Aluminum sulfide reacts with water to form aluminum hydroxide and hydrogen sulfide by the following reaction
Al₂S₃ + 6 H₂O $\rightarrow$ 2Al(OH)₃ + 3H₂S
If 25 g of aluminum sulfide is reacted with 25 g of water how many moles of hydrogen sulfide will be formed?

A) 0.12 moles
B) 0.50 moles
C) 0.78 moles
D) 2.0 moles
E) 3.0 moles

Question 8

Iron oxide can be reduced to iron by a reaction with carbon to form carbon monoxide
Fe₂O₃(s) + 3C(s) $\rightarrow$ 2Fe(s) + 3CO(g)
If 95.0 grams of iron oxide is reacted with excess carbon yields 63 g of iron, what is the percent yield of this reaction?

A) 12%
B) 59%
C) 66%
D) 95%
E) 100%

Question 9

Acetonitrile, CH₃CN, can be synthesized from carbon monoxide, hydrogen, and ammonia in the presence of a catalyst at high temperatures by the following reaction
2CO(g) + 2H₂(g)+NH₃(g) $\rightarrow$ CH₃CN(g) + 2H₂O(g)
If 20 g of carbon monoxide, 20 g of hydrogen, and 10 g of ammonia are reacted, which will be the limiting reagent?

A) carbon monoxide
B) hydrogen
C) ammonia
D) none of them
E) there is no way to know

Question 10

Which has a larger molar volume (the volume occupied by one mole):
Gold (density = 19.3 g cm^-3) or tin (density = 7.31 g cm^-3)?

A) gold
B) tin
C) they are exactly the same
D) there is no way to know without other information

Question 11

Copper oxide ore, CuO, can be smelted with carbon to make copper metal and carbon dioxide.
2CuO(s) + C(s) $\rightarrow$ 2Cu(s) + CO₂(g)
If 100.0 of a mixed ore is smelted and produces 75.9 grams of pure copper. What percentage of the mixed ore is CuO? (You can assume the reaction yield is 100%, there is excess carbon, and that CuO is the only source of copper.)

A) 28.0%
B) 48.5%
C) 75.9%
D) 79.9%
E) 95.0%

Question 12

A vanadium oxide contains 56.02% vanadium by mass. What is its empirical formula?

A) V₂O
B) VO
C) V₂O₃
D) VO₂
E) V₂O₅

Question 13

Caffeine has the molecular formula, C₈H₁₀N₄O₂. If it is burned in excess oxygen it will form carbon dioxide, water vapor, and nitrogen gas. Which gas will be most abundant by mass?

A) CO₂
B) H₂O
C) N₂
D) they will all the be the same
E) it depends on the mass of caffeine

Question 14

Triphenylene is an organic compound containing only carbon and hydrogen with 3 carbon atoms for every two hydrogen atoms. Which of the following is a possible molecular mass for triphenylene?

A) 34.0 g/mol
B) 228.29 g/mol
C) 366.8 g/mol
D) 400.0 g/mol
E) b or c could be correct

Question 15

Sodium perbromate can be synthesized via the following reaction that gives off Xenon gas.

A reaction is started with 200.0g of NaBrO₃, 250.0g of XeF₂ and 100.0g of water. Assuming that the reaction goes to completion, and that all of the formed xenon gas is allowed to escape into the atmosphere, what will be the minimum mass of products and reactants remaining in the reaction vessel?

A) 173.4 g
B) 193.9 g
C) 376.0 g
D) 356.1 g
E) None of the above