Question

Question Round your answer to the nearest integer The energy content of a certain food is to be determined in a bomb calorimeter that contains 2 kg of water by burning a 5-g sample of it in the presence of 136 g of air in the reaction chamber. If the water temperature rises by 3.2°C when equilibrium is established, determine the energy content of the food, in kJ/kg, by neglecting the thermal energy stored in the reaction chamber and the energy supplied by the mixer. Reaction chamber Food AT-3.2°C

Answer 1

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Using Table A-2,

By energy balance;

$E_{in}-E_{out} = \Delta E$

$\Rightarrow Q_{in}-0 = \Delta U$

$\Rightarrow m_{food}C=m_{air}c_{v,air}\Delta T + m_{w}c_{v,water}\Delta T$

$\Rightarrow (0.005)C=(0.136)(0.718)(3.2) + (2)(4.18)(3.2)$

$\Rightarrow C = 5413\;\;kJ/kg$

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