1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Determining the specific heat capacity of water

  1. Oct 20, 2016 #1
    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. jcsd
  3. Oct 20, 2016 #2

    CWatters

    User Avatar
    Science Advisor
    Homework Helper

    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?
     
  4. Oct 20, 2016 #3

    BvU

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Hi Juice, :welcome:

    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.
     
  5. Oct 20, 2016 #4
    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.
     
  6. Oct 20, 2016 #5

    BvU

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    How do you know they were errors ?
     
  7. Oct 20, 2016 #6
    Alright, I'll try that.
    Thank you BvU!!
     
  8. Oct 20, 2016 #7
    did you stir the water during the experiment?
     
  9. Oct 20, 2016 #8

    CWatters

    User Avatar
    Science Advisor
    Homework Helper

    +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.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Determining the specific heat capacity of water
Loading...