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2 years ago

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The enthalpy of combustion of benzoic acid (C6H5COOH) is commonly used as the standard for calibrating constant-volume bomb calo

rimeters; its value has been accurately determined to be −3226.7 kJ/mol. When 3.1007 g of benzoic acid are burned in a calorimeter, the temperature rises from 21.84°C to 24.67°C. What is the heat capacity of the bomb? (Assume that the quantity of water surrounding the bomb is exactly 2250 g.)

1 answer:

Anit [1.1K]2 years ago

7 0

<h3>Answer:</h3>

28.96 kJ/°C

<h3>Explanation:</h3>

We are given;

Enthalpy change (ΔH) = −3226.7 kJ/mol
The reaction is exothermic since the heat change is negative;
Mass of benzoic acid = 3.1007 g
Temperature change (21.84°C to 24.67°C) = 2.83°C

We are required to find the heat capacity of benzoic acid;

<h3>Step 1: Moles of benzoic acid </h3>

Moles = Mass ÷ molar mass

Molar mass of benzoic = 122.12 g/mol

Therefore;

Moles = 3.1007 g ÷ 122.12 g/mol

= 0.0254 moles

<h3>Step 2: Determine the specific heat capacity </h3>

Heat change for 1 mole = 3226.7 kJ

Moles of Benzoic acid = 0.0254 moles

But;

Specific heat capacity × ΔT = Moles × Heat change

cΔT = nΔH

Therefore;

Specific heat capacity,c = nΔH ÷ ΔT

= (3226.7 kJ × 0.0254 moles) ÷ 2.83°C

= 28.96 kJ/°C

Therefore, the specific heat capacity of benzoic acid is 28.96 kJ/°C

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