- #1

Janinever

- 13

- 0

My problem is with how they calculate the actual answer - this is from an example problem in my textbook.

## Homework Statement

A calorimeter cup is made from 0.15kg of Alu and contains 0.20 kg of water. Initially the water and cup have a common temp of 18C. A 0.040 kg mass of unknown material is heated to a temp of 97C and then added to the water. The temp of the water, the cup and unknown material is 22C after thermal equilibriam is reestablished. Ignoring small amount of heat gained by thermometer, find the heat capacity of the unknown material.

## Homework Equations

Using the equation that they've explained in the book and taking all the data and putting it in the equation (exactly as in my book) see below :

## The Attempt at a Solution

[9.00 x 10^2 J/(kg.C](0.15kg)(4.0C) + [4186 J/(kg.C)](0.20kg)(4.0C)

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(0.040kg)(75.0C)

The answer in the book is 1300 J/(kg.C)

With the calculator I get 1656.266667

So I have no clue how they got to 1300?

Please could someone help me understand how they get to the answer? I understand the rest.

Thanks so much!