Question

Upon complete combustion, the indicated substances eveolve the given quantities of heat. Write a balanced equation for the combustion of 1.00 mol of each substance, including the enthalpy change, ÄH, for the reaction.

a) 0.548g of propane, C3H8(g), yields 29.4 J
b) 2.35 mL of acetone, (CH3)2CO(l) (d=0.791 g/mL), yields 58.3J

This is just a practice homework question, can someone please just get me started on one, and I can probably do the rest.

Answer 1

C3H8 + 5O2 ==> 3CO2 + 4H2O
0.548 g C3H3 is 0.548/approximately 44 (you need to calculate it exactly) = about 0.01245 mols. So you had 0.1245 mol that evolved 29.4 J. Delta H is the amount evolved for 1.00 mol so
29.4 J/0.01245 mol = about 2360 J/mol.