## Joules or KJ?

Veronica Lu 2H
Posts: 89
Joined: Wed Sep 18, 2019 12:18 am
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### Joules or KJ?

when solving problems on the midterm, are we supposed to have final answers in J or kJ? or does it depend on the problem?

Paul Hage 2G
Posts: 105
Joined: Thu Jul 25, 2019 12:17 am

### Re: Joules or KJ?

Unless the problem specifies whether we should have our answer in Joules or kilojoules, I believe we could write our answer using either unit. The important thing is to make sure the units for different variables in a specific problem match.

Daniel Yu 1E
Posts: 100
Joined: Sat Aug 24, 2019 12:15 am

### Re: Joules or KJ?

I'm pretty sure it really doesn't matter whether you leave it Joules or KJ, as long as you convert correctly. I'm assuming if the quantities are given to you in KJ you would leave it as KJ, and the same for Joules, but it doesn't really matter as long as you have the same answer.

305421980
Posts: 101
Joined: Sat Sep 07, 2019 12:16 am

### Re: Joules or KJ?

I think it depends on what the problem asks for but generally doesn't matter. I would just be careful and make sure when solving everything is matching. Also I know that a lot of times enthalpies use KJ whereas entropy is often in J. So I would just be conscience of units as you go.

BNgo_2L
Posts: 95
Joined: Wed Sep 11, 2019 12:17 am

### Re: Joules or KJ?

It usually doesn't matter unless specified. However, the correct number of significant figures will determine if you write your answer in kJ or J.

Uisa_Manumaleuna_3E
Posts: 60
Joined: Wed Sep 21, 2016 2:56 pm

### Re: Joules or KJ?

Also, it also kinda helps to look at the answer you have and see which one (J/KJ) just makes more sense. Like, for some answers I would get something long like 1000000 J and that would be appropriate for the question. But like it just made more sense to shorten it to 1000 kj.

But yeah, they're both basically the same. Just do the normal rule of thumb and make sure all the units cancel out. Those are important.

Tiffany_Chen 2K
Posts: 106
Joined: Fri Aug 30, 2019 12:15 am

### Re: Joules or KJ?

Just make sure the constants you use (e.g. R), will match the units you want. Really depends on what the question asks for.

Posts: 113
Joined: Thu Jul 11, 2019 12:16 am

### Re: Joules or KJ?

I don't think it matters.

Gurmukhi Bevli 4G
Posts: 49
Joined: Wed Nov 14, 2018 12:20 am

### Re: Joules or KJ?

I don't think it matters provided your units stay consistent throughout the entire problem. If J/kJ are necessary the problem will probably specify which unit it wants/if it wants you to convert between units.

Veronica_Lubera_2A
Posts: 106
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### Re: Joules or KJ?

You should always check the units in the constants you plug into your formulas. So it would depend whether it's joules or kilojoules.

Callum Guo 1H
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### Re: Joules or KJ?

I don't think it matters unless the question specifically asks for a unit

Nuoya Jiang
Posts: 99
Joined: Sat Sep 14, 2019 12:17 am

### Re: Joules or KJ?

Most of the time J.

Anish Natarajan 4G
Posts: 51
Joined: Thu Jul 25, 2019 12:16 am

### Re: Joules or KJ?

Both work but I'd be careful to convert all your units to the same scale (either joules or kilojoules) because the equations we use for entropy give us the answer in joules whereas the equations we use to calculate enthalpy frequently use kilojoules

pmokh14B
Posts: 107
Joined: Sat Aug 17, 2019 12:15 am

### Re: Joules or KJ?

Either works, unless it's specified in the problem.

Natalie Benitez 1E
Posts: 100
Joined: Fri Aug 02, 2019 12:15 am

### Re: Joules or KJ?

Why does entropy and enthalpy have different units?