## kj v j in calculations?

$\Delta U=q+w$

aisteles1G
Posts: 117
Joined: Fri Sep 28, 2018 12:15 am

### kj v j in calculations?

Im kind of confused as to when heat is in J and when in KJ, for example a solution gives: q=mCΔT= (80.0g)(4.187J/C/g/)(20C-0C)=6.69kJ but the specific heat is given in J so I don't understand why the answer is in KJ? Is this just an error or am I missing something? Thanks for any help!

ariana_apopei1K
Posts: 89
Joined: Fri Sep 28, 2018 12:27 am
Been upvoted: 1 time

### Re: kj v j in calculations?

I noticed this too, sometimes they even give the answer in both J and KJ. I doubt you'd be marked wrong on a test for having one over the other though

Kelsey Warren 1I
Posts: 60
Joined: Fri Sep 28, 2018 12:15 am

### Re: kj v j in calculations?

If the heat/energy value is really large (>10^3), then use kJ so that your numerical answer won't be so huge. If your heat/energy value is smaller, you can use J. It's really just dependent on the size of the numbers you're dealing with.