Question

When 0.0167 g of a compound with a heat of combustion of -41.6 kJ/mole is burned
in a calorimeter, 28.15 J of heat is released. What is the molar mass of the compound?

Answer 1

∆H$^{\theta}{_c}=-41.6kJmol^{-1}$

$=-41600Jmol^{-1}$

Number of moles that releases 28.15J of heat

$=\frac{28.15}{41600} moles$

Therefore $\frac{28.15}{41600} moles$ is equivalent to

0.0167g

Molar mass $=0.0167÷(\frac{28.15}{41600})$

$=0.0167×\frac{41600}{28.15}$

= 24.6792g