Stoichiometry Problems
1. The average human requires 120.0 g of glucose (C₆H₁₂O₆) per day. How many
grams of CO₂ (in the photosynthesis reaction) are required in order to produce
this amount of glucose? The photosynthesis reaction is:
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
Unknown: mass of CO₂
Given: mass of glucose = 120g
Molar mass of C₆H₁₂O₆ = (6x12.011) + (12x1.008) + (6x15.999) =
180.156 g/mol
Grams to moles:
120 g C₆H₁₂O₆ / 180.156 g/mol = 0.666 mol
0.666 mol C₆H₁₂O₆ ÷ 1 mol C₆H₁₂O₆ x 6 mol CO₂ = 3.996 mol CO₂
Moles to grams:
3.996 mol CO₂ x 44.009 g/mol = 175.86 g
∴ 175.86 g of CO₂ can produce 120 g of C₆H₁₂O₆.
2. Molten iron and carbon monoxide are produced in a blast furnace by the reaction
of iron (III) oxide and coke (pure carbon). If 25.0 mol of pure Fe₂O₃ is used, how
many grams of iron can be produced? The reaction is:
1. The average human requires 120.0 g of glucose (C₆H₁₂O₆) per day. How many
grams of CO₂ (in the photosynthesis reaction) are required in order to produce
this amount of glucose? The photosynthesis reaction is:
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
Unknown: mass of CO₂
Given: mass of glucose = 120g
Molar mass of C₆H₁₂O₆ = (6x12.011) + (12x1.008) + (6x15.999) =
180.156 g/mol
Grams to moles:
120 g C₆H₁₂O₆ / 180.156 g/mol = 0.666 mol
0.666 mol C₆H₁₂O₆ ÷ 1 mol C₆H₁₂O₆ x 6 mol CO₂ = 3.996 mol CO₂
Moles to grams:
3.996 mol CO₂ x 44.009 g/mol = 175.86 g
∴ 175.86 g of CO₂ can produce 120 g of C₆H₁₂O₆.
2. Molten iron and carbon monoxide are produced in a blast furnace by the reaction
of iron (III) oxide and coke (pure carbon). If 25.0 mol of pure Fe₂O₃ is used, how
many grams of iron can be produced? The reaction is:
