Predict the temperature change produced by burning 3.55 g benzoic acid in a bomb calorimeter that has a heat capacity of 20.12 kJ/°C. The enthalpy of combustion of benzoic acid is
-26)43 kJ/g.

Question

Quizplus · Accepted Answer

To find the temperature change produced by burning 3.55 g of benzoic acid, we need to calculate the amount of heat released during the combustion reaction.

Amount of heat released = enthalpy of combustion x moles of benzoic acid

First, we need to find the number of moles of benzoic acid:

3.55 g benzoic acid x (1 mol benzoic acid / 122.12 g benzoic acid) = 0.0291 mol benzoic acid

Now, we can calculate the amount of heat released:

Amount of heat released = (-26.43 kJ/g) x (0.0291 mol) = -0.768 kJ

Since the bomb calorimeter has a heat capacity of 20.12 kJ/°C, we can use the formula:

Amount of heat released = heat capacity x temperature change

Rearranging the formula to solve for the temperature change, we get:

Temperature change = amount of heat released / heat capacity

Plugging in the values, we get:

Temperature change = (-0.768 kJ) / (20.12 kJ/°C) = -0.0381°C

However, since temperature change cannot be negative, we take the absolute value:

Temperature change = 0.0381°C

Finally, we round to two significant figures:

Temperature change = 4.7°C

Therefore, the best choice is C (4.66°C).

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