chemtisty-calorimetry

Question

A total of 2.00  of a compound is allowed to react with water in a foam coffee cup and the reaction produces 181  of solution.

The reaction caused the temperature of the solution to rise from 21.00  to 24.70 . What is the enthalpy of this reaction?

Assume that no heat is lost to the surroundings or to the coffee cup itself and that the specific heat of the solution is the same as that of pure water.

Enter your answer in kilojoules per mole of compound to three significant figures.

Answer 1

In your question, you didn't provide units for 2.00 and 181, so I'll assume the problem is supposed to read..

"2.00 mol of a compound is allowed to react with water in a foam coffee cup and the reaction produces 181g of solution". Assuming this is what you meant, here is the solution to the problem...

q = mC∆T

q = heat = ?

m = mass = 181 ml x 1 g/ml = 181 g (assuming a density of 1g/ml)

C = specific heat = 4.184 J/g/degree (assuming the same specific heat as water)

∆T = change in temperature = 24.70 - 21.00 = 3.70 degrees

q = (181 g)(4,184 J/g/degree)(3.70 degrees)

q = 2802 J = 2.802 kJ

To find kJ/mole as asked in the question, we simply divide this by the number of moles (2.00 moles)..

2.802 kJ/2.00 moles = 1.40 kJ/mole