Question

17. When combusted in a bomb calorimeter, a 12.6 g sample of acetylene (C2H2) produced a temperature increase of 16.9 °C. The calorimeter constant for the calorimeter was determined to be 31.5 kJ/°C. What is the molar heat of combustion for acetylene? a. -6.71 x 103 kJ/mol b. -1.10 x 103 kJ/mol C. -42.25 kJ/mol d. -13.5 x 103 kJ/mol e. -532 kJ/mol

Answer 1

It principle of According to rime troy calo- Heat produced by the combustion reaction = Heat absorbed by the Calorimeter. Now , given. Calorimeter constant, C = 31.5 kJ/ec. Again, Temperature increas, D AT = 16.9°C e. Heat absorbed by calorimeter = Cal XOT = 31.55 kalf x 16.9 of = 532.35 kJ As, in the combustion socaction heat is brooduced, the heat of

the combustion reaction would be negative . q pn = - 532.35 kJ Now, molar mass of acetylene (CH2) = 26 g/mol . 12.6 g of C H2 = 12.6 g . = 0.485 mol a 26 g/mol Calta Thus the molar heat of combustion reaction can be given as am iren

- 532.35 kJ 0.485 mot = - 1.097 x 103 kJ/mol 2 - 1.10 x 103 kJ/mol three significant I figures] the connect option would b. - 1. 10 x 103 kJ/mol Aws Thus be