Question

Under constant-volume conditions the heat of combustion of benzoic acid (C6H5COOH) is 26.38 kJ/g. A 2.790 −g sample of benzoic acid is burned in a bomb calorimeter. The temperature of the calorimeter increases from 21.60 ∘C to 29.95 ∘C.

A. What is the total heat capacity of the calorimeter?

B. A 1.460 −g sample of a new organic substance is combusted in the same calorimeter. The temperature of the calorimeter increases from 22.14 ∘C to 27.09 ∘C. What is the heat of combustion per gram of the new substance?

C.

Suppose that in changing samples, a portion of the water in the calorimeter were lost. In what way, if any, would this change the heat capacity of the calorimeter?

Suppose that in changing samples, a portion of the water in the calorimeter were lost. In what way, if any, would this change the heat capacity of the calorimeter?

the heat capacity decreases

the heat capacity increases

the heat capacity stays the same

Answer 1

Under constant volume conditions heat of combustion of Benzoic acid (464scoon) is - 26.38 kJ lg So, heat of combustion for 2.190g of benzoic acid = 26:38 X 2.790 = 73.6K1 1. - A) So, a cal = Ceal x ot a cal = heat of combustion OT = Ti-Ti = 29.95 - 21.600c Ceal - heat capauty of 1 calorimeter = 8.35°C DT = Change in temperature Ccal = ace 1. q. 35 1.46 g g new organic substance OT: 27.09 - 22.14°C = 4.195°C - 73.6 KI=8.814 kg9°C B.) combustion = Ccal X AT = 8.814X 4.95°C 4-3.63 kJ Heat as combustion for go new Substance = 43.63 1.460 - 29.89 kJ/g c.) we know (w = Swx mw Cwe heat capacity Heat capacity is an extensive of water property. The calorimeter exists Sw = specific heat as a fixed unit capacity thus its heat capacity mw = marsey water is a fixed value. The amount of water in the calorimeter however can vary. So, if mass of water decuases. Cw= sw x mw so heat capacity of water decreases which implies heat capacity decreases.