Question

Using the balanced equation shown below, calculate the mass of c3h8 that must react in order to release 2.45×106 × 106 kj of heat. δhrxn = –2219.9 kj

Answer 1

The balanced chemical equation for this is:

C3H8  +  5 O2  -->  3 CO2  +  4 H2O

 

So we can see that for every 1 mole of C3H8, 2219.9 kJ of energy is released. Hence the total number of moles of C3H8 required is:

 

moles C3H8 = 2.45×10^6 kJ / (2219.9 kJ / mol)

moles C3H8 = 1103.65 mol

 

The molar mass of C3H8 is 44.1 g/mol, therefore the mass is:

 

mass C3H8 = 1103.65 mol * 44.1 g/mol

mass C3H8 = 48,671.11 grams = 48.67 kg