Question

1. When 1.50 g of biphenyl (C12H10) burns in a bomb caIorimeter the temperatute rises from 25.15 C to 33.33 C. The heat Capacity of the caiorimeer is 5.86 kj/ C. Calculate: a) qrxn per mole of biphenyl for the combustion process b) qrxn per gram of biphenyl for the combustion process

Answer 1

m = 1.50 g of Byphenil

MW = 154.21

mol = masS/MW = 1.5/154.21 = 0.00973

Ti = 25.15

Tf = 33.33

Cp = 5.86 kJ/C

a)

qrxn per mol

Q = C*(Tf-Ti)

Q = 5.86 kJ/C (33.33-25.15) = 47.93 kJ

Q = 47.94 kJ

Qrxn = 47.94 kJ/0.00973mol = 4927 kJ/mol

Qrxn = 4927 kJ/mol

b)

qrxn per gram

Same heat...

Q = 47.94 kJ

Qrxn = 47.94 kJ/1.5g = 31.96 kJ/g