What mass of propane c3h8 is needed to produce 346 g carbon dioxide In the following reaction

Question

 None

Answer 1

Hi Ashlee,

 

You did not mention a reaction in your following reaction, but if it is a combustion/burning reaction and is the following: 

 

C₃H₈ + 5O₂ -> 3CO₂ + 4H₂O

 

You will need to first start with 346 g of CO₂. To get mass of propane, we will need to find the conversion factor between carbon dioxide and propane. This will be our mole:mole ratio.

 

We want to first convert our mass of carbon dioxide (346 g) to mol carbon dioxide. To do that, we use the molar mass of carbon dioxide. This is 44.01 g/mol. To get mol of carbon dioxide, we divide our mass by the molecular weight.

 

346 g / (44.01 g/mol) ~ 7.8618 moles of CO₂

 

After this, we have to look at our balanced reaction, to get the mole:mole ratio. We know that for every 3 mol of CO_{2 ,} we need to burn 1 mol of propane.

 

This means that we can divide 7.8618 mol CO₂ by 3 to get the mol of propane burned. 

 

7.8618 mol CO₂ / (3 mol CO₂ / 1 mol C₃H₈) = 2.6206 mol C₃H₈

 

From this, we can get mass of propane by multiplying the mol of propane by its molecular weight (44.1 g C₃H₈ / 1 mol C₃H₈).

 

2.6206 mol C₃H₈ * (44.1 g C₃H₈ / 1 mol C₃H₈). ~ 115.57 g 

 

With 3 sig.figs, the answer is about 116 g.