Calculating the Mass of Propane Needed in a Chemical Reaction

21 Jun 2021

Question:

What mass of propane (C3H8) is needed to produce 346 g carbon dioxide in the following reaction?

The answer to this question is 115 grams.

Mass of CO2: 346 g
Molar mass of C3H8: 44 g/mole
Molar mass of CO2: 44 g/mole

First, we need to calculate the moles of CO2.

Moles of CO2 = Mass of CO2 / Molar mass of CO2 = 346g / 44g/mole = 7.86 moles

Next, we calculate the moles of C3H8 using the balanced chemical reaction:

C3H8 + 5O2 → 3CO2 + 4H2O

From the balanced reaction, we know that 3 moles of CO2 are obtained from 1 mole of C3H8.

So, 7.86 moles of CO2 react to give (1/3) × 7.86 = 2.62 moles of C3H8.

Now, we can calculate the mass of C3H8:

Mass of C3H8 = Moles of C3H8 × Molar mass of C3H8

Mass of C3H8 = 2.62 moles × 44 g/mole = 115.28g ≈ 115g

Therefore, the mass of propane needed to produce 346 g of carbon dioxide is 115 grams.