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Dmitriy789 [7]
3 years ago
7

Gram for gram, fats in food have much more chemical energy than sugar. One component of fat is stearic acid, C18H36O2. When a sa

mple of 1.02 g of stearic acid was burned completely in a bomb calorimeter, the temperature of the calorimeter rose by 4.26oC. The heat capacity of the calorimeter was 9.43 kJ/oC. Calculate the molar heat of combustion of stearic acid in kilojoules per mole.
Chemistry
1 answer:
vodka [1.7K]3 years ago
3 0

Answer:

\mathbf{-1.12 \times 10^4 \ kJ/mol}

Explanation:

Given that:

mass (m) of the sample = 1.02 g

number of moles of stearic acid  =\dfrac{mass}{molar mass}

= \dfrac{1.02 \ g}{284.49 \ g/mol} \\ \\ = 0.000358 \ moles

The change in temp. \Delta T = 4.26^0 \ C

heat capacity of the calorimeter (c) = 9.43 kJ/° C

Thus, heat due to reaction = cΔT

= 9.43 kJ/° C × 4.26° C

= 40.17 kJ

The heat in kJ/mol = \dfrac{40.17 \ kJ}{0.00358 \ mol}

= 11204.23 kJ/mol

= 1.12 × 10⁴ kJ/mol

As a result of  the reaction is exothermic, the heat reaction of the  combustion is:

\mathbf{-1.12 \times 10^4 \ kJ/mol}

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