# Homework Help: Determining the specific heat capacity of water

Tags:
1. Oct 20, 2016

### VegemiteJuice

1. The problem statement, all variables and given/known data
Hi,
I have an assignment to determine the specific heat capacity of water using a calorimeter, voltmeter and ammeter, where we connected the calorimeter to a 10V power pack and measured the temp of the water and the readings on the voltmeter and ammeter every minute. I ended up having a huge random error for the voltmeter and ammeter (3.01%) - any idea why this is?
Also what should I talk about in my discussion?

2. Relevant equations
To calculate the specific heat capacity I used
PΔt = mc(water)ΔT + mc(calorimeter)ΔT
and I got a value of 3.95 +- 3.45% J g-1 K-1

2. Oct 20, 2016

### CWatters

What do you mean by a "huge random error for the voltmeter and ammeter"? Were the readings fluctuating up and down? Changed gradually over time?

3. Oct 20, 2016

### BvU

Hi Juice,

So you have three series of T, I and V as a function of time. It would be logical to plot them as a function of time to see if the errors are really random, or that there is more going on.

4. Oct 20, 2016

### VegemiteJuice

We wrote down the measurements displayed on the ammeter and voltmeter every minute, until the water had increased by over 20K (it took 5 minutes). The readings on each fluctuated every time, and the random errors were 0.11A and 0.1V, which ended up being quite a large % error.

5. Oct 20, 2016

### BvU

How do you know they were errors ?

6. Oct 20, 2016

### VegemiteJuice

Alright, I'll try that.
Thank you BvU!!

7. Oct 20, 2016

### lychette

did you stir the water during the experiment?

8. Oct 20, 2016

### CWatters

+1 to the questions above.

Also..

How many digits could the meters display? 10.1V is three significant digits. Could it display 10.05V or is 10.1V the nearest it can get?
What was a typical current? Something like 3.11A is also three significant digits.