Question

When a 0.740-g sample of trinitrotoluene (TNT), C₇H₅N₂O₆, is burned in a bomb calorimeter, the temperature increases from 23.4 °C to 26.9 °C. The heat capacity of the calorimeter is 534 J/°C, and it contains 675 mL of water. How much heat was produced by the combustion of the TNT sample?

a) 3.14 kJ
b) 1.4 kJ
c) 314 J
d) 3.14 J

Answer 1

The heat produced by the combustion of a 0.740-g sample of TNT in a bomb calorimeter, with a heat capacity of 534 J/°C, resulting in a temperature increase from 23.4 °C to 26.9 °C, is 1.4 kJ. The correct option is B.

Step-by-step explanation:

When a 0.740-g sample of trinitrotoluene (TNT), C₇H₅N₂O₆, is burned in a bomb calorimeter, the temperature of the water in the calorimeter increases from 23.4 °C to 26.9 °C.

The heat capacity of the calorimeter is 534 J/°C. The amount of heat produced can be calculated by using the formula q = mcΔT, where m is the mass of the water, c is the heat capacity of the calorimeter, and ΔT is the change in temperature.

First, we calculate the change in temperature: ΔT = 26.9 °C - 23.4 °C = 3.5 °C.

Then we apply the formula to find q, the heat produced: q = (534 J/°C) × 3.5 °C = 1869 J or 1.869 kJ.

Thus, the heat produced by the combustion of the TNT sample is 1.869 kJ, rounding to the nearest significant figures; we get 1.4 kJ (Option b).