Question

A slice of banana weighing 2.502 g was burnt in a bomb calorimeter
producing a temperature rise of ${3.05}^{\circ }C$. The combustion of
0.316 g of benzoic acid in the same calorimeter produced a temperature
rise of ${3.24}^{\circ }C$. The heat of combustion of benzoic acid at
constant volume is $-3227kJmo{l}^{-1}$. If average banana mass
is 125 g, the kilojoules of energy can be obtained from 1 average
banana is

• A. 393
• B. 350
• C. 450
• D. 850

Answer 1

The correct option is A 393

$q=mS.\Delta T$ for combustion of benzoic acid
($Note:$ In bomb calorimeter reaction is made at constant volume)
$\frac{0.316\times 3227}{122}=m\times S\times 3.24$
$\therefore$ Water equivalent of bomb calorimeter $\left(mS\right)$
$=\frac{0.316\times 3227}{122\times 3.24}=2.58kJ{/}^{\circ }C$
For banana slice; $q=mS\times \Delta T$
$q=2.58\times 3.05$
$=7.87kJper2.502gbanana$
$\therefore Heatproducedby125gbanana=\frac{7.87\times 12.5}{2.502}=393.18kJ$
so nearest integer value is 393.