Combustion of 5.6554 grams of C4H10 will yield _____ grams of CO2. (Assume 100% yield)

Question

Combustion of 5.6554 grams of C4H10 will yield _____ grams of CO2. (Assume 100% yield).

The answer is 17.13.

Please list the steps to get to this answer.

Answer 1

Step 1: Write the chemical reaction equation (don't bother to balance it yet, you'll do that in step 2)

A combustion reaction always combines a hydrocarbon with oxygen and yields carbon dioxide and water so:

C₄H₁₀ + O₂ → CO₂ + H₂O

Step 2: Balance the chemical reaction equation

Notice there are an odd number of O's on the right side of the equation and an even number on the left. The only way to get this to balance is to put an even number in front of the H₂O. We have 10 hydrogens on the left so we want to get 10 on the right but that would require adding a 5 in front of the H₂O (which is not an even number). So, we need to double the 5 and make it 10 so:

C₄H₁₀ + O₂ → CO₂ + 10H₂O

That make us need to put a 2 in front of the C₄H₁₀ to get the hydrogens to balance so:

2C₄H₁₀ + O₂ → CO₂ + 10H₂O

That makes us need to add an 8 in front of the CO₂ to get the carbons to balance so:

2C₄H₁₀ + O₂ → 8CO₂ + 10H₂O

That means we need to add a 13 in front of the O₂ to get the oxygens to balance. so:

2C₄H₁₀ + 13O₂ → 8CO₂ + 10H₂O

Step 3: Calculate the number of moles in 5.6554 grams of C₄H₁₀ - the chemical reaction equation is in units of moles, so to use it, we need to know the moles of C₄H₁₀

First we find the molar mass of C₄H₁₀ - (4)(12.011) + (10)(1.008) = 58.124 g/mol

Second, using the 5.6554 grams of C₄H₁₀, we divide by 58.124 g/mol to get 0.09729888 moles of C₄H₁₀

Step 4: Using the molar ratios in the chemical reaction equation, find the number of moles of CO₂.

The chemical reaction equation says that for every 2 moles of C₄H₁₀ there are 8 moles of CO₂ produced so we multiply the 0.09729888 moles of C₄H₁₀ by 8 and divide by 2 making 0.3891955 moles of CO₂.

Step 5: Convert moles of CO₂ to grams of CO₂ using the molar mass.

The molar mass of CO₂ is (1)(12.011) + (2)(15.999) = 44.009 g/mol. We now multiply the number of moles of CO₂ by the molar mass to get 17.128 g. The answer should have 5 sig figs because the original given had 5 but they've rounded it to 4 sig figs for some reason unknown to me.