Question

Ethyne (C2 H2 (g), mc032-1.jpgHf = 226.77 kJ/mol) undergoes complete combustion in the presence of oxygen to produce carbon dioxide (CO2 (g), mc032-2.jpgHf = –393.5 kJ/mol ) and water (H2 O(g), mc032-3.jpgHf = –241.82 kJ/mol) according to the equation below.
mc032-4.jpg

What is the enthalpy of combustion (per mole) of C2 H2 (g)?
–2511.2 kJ/mol
–1255.6 kJ/mol
–862.1 kJ/mol
–431.0 kJ/mol

Answer 1

2 C2H2 + 5 02  >  4 CO2 + 2 H2O

Products  - Reactants ( all units are kJ/mo1):

(4 x -393.5) + (2 x -241.82) - (2 x 226.77) - (5 x 0) = -2511.2 kJ/mo1

-2511.2 kJ/mo1 is for 2 moles of C2H2.The question asked for 1 mole of C2H2, so: -2511.2 / 2 = -1255.6 kJ/mo1

answer: -1255.6 kJ/mo1

Answer 2

Answer:

B. –1255.6 kJ/mol

Explanation:

this is correct on ed-genuity, hope this helps! :)