Question

Oxyacetylene torches produce such high temperature that they are often used to weld and cut metal. When 1.53 g of acetylene (C2H2) is burned in a bomb calorimeter with a heat capacity of 10.69 kJ/K, the temperature increases from 20.486°C to 44.688°C. What is ΔE (in kJ/mol) for this combustion reaction? Enter to 0 decimal places.

Answer 1

Answer: $4403kJ/mole$

Explanation:

First we have to calculate the heat absorbed by bomb calorimeter  

Formula used :

$q_b=c_b\times (T_{final}-T_{initial})$

$q_b$ = heat absorbed by calorimeter = ?

$c_b$ = specific heat of = 10.69 kJ/K

$T_{final}$ = final temperature = $44.688^oC=(273+44.688)K=317.688K$

$T_{initial}$ = initial temperature = $20.486^oC=(273+20.486)K=293.486K$

$q_b=10.69kJ/K\times (317.688-293.486)=258.7kJ$

As heat absorbed by calorimeter is equal to the heat released by acetylene during combustion.

Thus 1.53 gram of acetylene releases heat of combustion = 258.7kJ

So, 26.04 g/mole of acetylene releases heat of combustion $\frac{258.7}{1.53}\times 26.04=4403kJ/mole$

Therefore, the heat of combustion of acetylene is, $4403kJ/mole$