Question

If a pork roast must absorb 1700 kj to fully cook, and if only 14% of the heat produced by the barbeque is actually absorbed by the roast, what mass of co2 is emitted into the atmosphere during the grilling of the pork roast?

Answer 1

The amount of heat needed to cook the pork roast is 1700 kJ.

The amount of heat absorbed by the roast is 14% of the heat produced  = 14% X ?H = 310.38 kJ/mol

One mole of propane burns to produce 3 moles of CO2 and -2217 kJ of heat.

1700kJ/ (14% X ?H) = mol of C3H8 burned

1700kJ / (310.38 kJ/mol) = 5.48 mol C3H8

Since 3 moles of CO2 are produced:

3 X 5.48 mol= 16.43 mols of CO2

convert moles to grams:

16.43 mol CO2 X 44.0g/mol ~ 722.9 g CO2 produced