High-purity benzoic acid (c6h5cooh; δhrxn for combustion = −3227 kj/mol) is used as a standard for calibrating bomb calorimeters. a 1.221-g sample burns in a calorimeter (heat capacity = 1365 j/°c) that contains exactly 1.430 kg of water. what temperature change is observed?

Answer : The temperature change observed is

Explanation :

First we have to calculate the heat released by the combustion of benzoic acid.

where,

q = heat released by combustion of benzoic acid = ?

n = moles of benzoic acid =

= enthalpy of combustion = 3227 kJ/mole

Now put all the given values in the above formula, get:

Now we have to calculate the heat absorbed.

Heat released by combustion = Heat absorbed by the calorimeter + Heat absorbed by the water

where,

q = heat released by the combustion = 31947.3 J

= heat absorbed by the calorimeter

= heat absorbed by the water

= specific heat of calorimeter =

= specific heat of water =

= mass of water = 1.430 kg  = 1430 g

= change in temperature = ?

Now put all the given values in the above formula, we get:

Therefore, the temperature change observed is

it is b that is the answer.