1. The combustion of propane (C3H8) in the presence of excess oxygen yields CO2 and H2O:
C3H8 (g) + 5O2 (g) → 3CO2 (g) + 4H2 O (g)
When 2.5 mol of O2 are consumed in their reaction, ________ mol of CO2 are produced.
A) 1.5
B) 3.0
C) 4.2
D) 7.5
E) 2.5
2. Under appropriate conditions, nitrogen and hydrogen undergo a combination reaction to yield ammonia:
N2 (g) + 3H2 (g) → 2NH3 (g)
If the reaction yield is 81.4 %, how many moles of N2 are needed to produce 8.50 mol of NH3?
A) 20.9
B) 10.4
C) 5.22
D) 6.92
E) 15.7
3. How many moles of magnesium oxide are produced by the reaction of 1.82 g of magnesium nitride with of water?
Mg3N2 + 3H2O → 2NH3 + 3MgO
A) 0.0180
B) 0.0541
C) 0.00601
D) 0.984
E) 3.00
4. Sulfur and oxygen react in a combination reaction to produce sulfur trioxide, an environmental pollutant:
2S (s) + 3O2 (g) → 2SO3 (g)
In a particular experiment, the reaction of 1.0 g S with 1.0 g O2 produced 0.80 g of SO3. The % yield in this experiment is ________.
A) 32
B) 80
C) 21
D) 64
E) 47