A pellet of naphthalene of mass 1.234 g is burned in a bomb calorimeter with Ccal=14225 JK^−1. If the initial temperature is 298.150K and the final temperature is 301.634 K, find ΔU and ΔH for 1 mol of reaction, with liquid water as one of the products. Neglect the heat of combustion of the wire

Question

A pellet of naphthalene of mass 1.234 g is burned in a bomb calorimeter with [latex]C_{cal}=14225 JK^{−1}[/latex]. If the initial temperature is 298.150K and the final temperature is 301.634 K, find ΔU and ΔH for 1 mol of reaction, with liquid water as one of the products. Neglect the heat of combustion of the wire fuse.

Accepted Answer

The balanced reaction equation is

[latex]C_{10}H_{8}(s)+12O_{2}(g)\longrightarrow 10CO_{2}(g)+4H_{2}O(l)[/latex]

[latex]q=\Delta U=-q_{cal}=-(14225JK^{-1})(3.484K)=-4.956×10^{4}J[/latex]

For 1 mol of reaction

[latex]\Delta U=-\frac{(4.956×10^{4}J)}{(1.234g)}(\frac{128.19g}{1mol})=-5.148×10^{6}Jmol^{-1}[/latex]

[latex]\Delta H=-5.148×10^{6}Jmol^{-1}+(-2)(8.3145JK^{-1}mol^{-1})(298.15K)[/latex]

[latex]=-5.153×10^{6}Jmol^{-1}=-5153kJmol^{-1}[/latex]

This value compares with the published value,[latex]\Delta H°=-5156.8kJmol^{-1}[/latex] which applies to a constant-temperature reaction at 298.15 K.

Question 2.34: A pellet of naphthalene of mass 1.234 g is burned in a bomb ...

This Question has been Answered.

Already have an account?

Login

Related Answered Questions