# Question about Q=mcΔT when doing calorimetry

## Homework Statement

When using the equation Q=mcΔT for the substance being tested is it the mass of the substance or the mass of the substance + mass of water.

## The Attempt at a Solution

So when I solve calorimetry problems, I usually find Qwater. Then I set Qsubstance=-Qwater. But then I have to use mcΔT, I'm not sure if it's the mass of the substance or the mass of the substance + mass of the water because I've gotten a few questions wrong and the textbook briefly mentioned the sum of masses but gave no examples. Thanks for your input.

c = $\frac{Q}{mΔT}$

Since 'c' is for the substance, what would 'm' be for?

m is for the substance right? Not the sum of the mass of the water and substance.

m is for the substance right? Not the sum of the mass of the water and substance.
Yes, and you can relate to the definition of specific heat: energy required to raise the temperature of one unit mass of the 'substance' on unit degree.

Borek
Mentor
Yes, and you can relate to the definition of specific heat: energy required to raise the temperature of one unit mass of the 'substance' on unit degree.

Like specific heat of brine :tongue: