Chemical equation stoich

Question

How much C2H4N2 could be expected from the reaction of 14.1 g CO2, 2.17 g NH3, and 1.73 g CH4?

Answer 1

1. Write an unbalanced chemical reaction equation:

CO₂ + NH₃ + CH₄ → C₂H₄N₂ + H₂O

2. Balance the equation:

5CO₂ + 8NH₃ + 3CH₄ → 4C₂H₄N₂ + 10H₂O

3. Calculate the molar mass of the compounds involved:

Looking up each element in the periodic table:

CO₂:

C: 12.011 x 1 = 12.011

O: 15.999 x 2 = 31.998

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CO₂: = 44.009 g/mol

NH₃:

N: 14.007 x 1 = 14.007

H: 1.008 x 3 = 3.024

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NH₃: = 17.031 g/mol

CH₄:

C: 12.011 x 1 = 12.011

H: 1.008 x 4 = 4.032

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CH₄: = 16.043 g/mol

C₂H₄N₂:

C: 12.011 x 2 = 24.022

H: 1.008 x 4 = 4.032

N: 14.007 x 2 = 28.014

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C₂H₄N₂: = 56.068 g/mol

4. Calculate the number of moles of the known compounds:

(14.1 g CO₂)/(44.009 g/mol) = 0.3204 moles of CO₂

(2.17 g NH₃)/(17.031 g/mol) = 0.1274 moles of NH₃

(1.73 g CH₄)/(16.043 g/mol) = 0.1078 moles of CH₄

5. Determine the limiting reactant;

In looking at the balanced chemical reaction equation, it takes 5 moles of CO₂ to mix with 8 moles of NH₃ and 3 moles of CH₄. In looking at the number of moles we have of each, we can see that NH3 is the limiting reactant. So we base the rest of the calculations on the fact that there is 0.1274 moles of NH₃. That means I will need (5/8)(0.1274 moles) or 0.0796 moles of CO₂ (the rest will be just extra and will not be consumed in the reaction). It also means I will need (3/8)(0.1274 moles) or 0.0478 moles of CH₄. Again, the rest will be just extra and will not be consumed in the reaction.

The balanced chemical reaction equation says I will yield (4/8)(0.1274 moles) or 0.0637 moles of C₂H₄N₂

5. Calculate the grams of C₂H₄N₂ produced.

(0.0637 moles of C₂H₄N₂)(56.068 g/mol) = 3.57 g of C₂H₄N₂

This is the absolute best case. In most cases, there will be some amount lost due to imperfect conditions.