Question

The combustion of C₂H₄O(g) has a ΔH_rxn value of –2308.8 kJ. What is the enthalpy change when 218 g of CO₂(g) is produced? Report your answer to the nearest kJ (with no decimal places, include sign, do not include units).

Answer 1

The balanced combustion reaction is

2C2H4O(g) + 5O2(g) ------> 4CO2(g) + 4H2O(g)  ΔHrxn=-2308.8 kJ.

Given mass of CO2(g)=218 g and molar mass of CO2=44 g/mol.

Therefore moles of CO2=mass/molar mass=218 g/44 g/mol=4.954 mol.

From the balanced equation, for 4 moles of CO2 production, ΔHrxn=-2308.8 kJ,

then for 4.954 mol CO2 , ΔHrxn=?

ΔHrxn=(4.954 mol x -2308.8 kJ)/4 mol=-2859.76 kJ

ΔHrxn ~ -2860 kJ.

ΔHrxn=-2860.

Please let me know if you have any doubt. Thanks