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AS - Chem Q on q=mc[delta]t watch

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1. q=mc[delta]t

...what units is q in? My textbook says kJ, but the answers to my exam papers seem to be taking those units as J.

I'm so confuuuuuuuuuuuused.

2. It depends what units u are given for c.
3. (Original post by zombie)
q=mc[delta]t

...what units is q in? My textbook says kJ, but the answers to my exam papers seem to be taking those units as J.

I'm so confuuuuuuuuuuuused.

Well 1 kJ = 1000 J.
4. (Original post by Nylex)
Well 1 kJ = 1000 J.
Usually for AS chem take it to be J then convert it to an enthalpy.
5. Joules is the correct answer because the specific heat capacity of water is measured in joules remember. You then divide by 1000 to get it in Kj or Kj mol-1 as most questions will ask.
6. specific heat capacity of water is usually in kJ per K per kg. ( as in it takes 4.12 kJ to heat one kg of water by one K) This means that the answer is in kJ. That's why u have to convert the mass into kg.
7. (Original post by Happyelf)
specific heat capacity of water is usually in kJ per K per kg. ( as in it takes 4.12 kJ to heat one kg of water by one K) This means that the answer is in kJ. That's why u have to convert the mass into kg.
No no no!!!

Specific heat capacity of water:

c=4.18 J g-1 K-1. This is the STANDARD UNIT

Learn that right!!
8. (Original post by vinny2256)
No no no!!!

Specific heat capacity of water:

c=4.18 J g-1 K-1. This is the STANDARD UNIT

Learn that right!!
J g-1 K-1 is the same as kJ kg-1 K-1

...i do believe...try it with some figures
9. (Original post by Happyelf)
J g-1 K-1 is the same as kJ kg-1 K-1

...i do believe...try it with some figures

Kj Kg-1 K-1 is NOT THE STANDARD UNIT!!!! Read what im saying!!
10. that's what i have written in my module book so i'm going with that....and it is the same anyway so it doesn't matter...and in the exam it doesn't matter which units u use unless it asks u for specific units.
11. (Original post by vinny2256)
Kj Kg-1 K-1 is NOT THE STANDARD UNIT!!!! Read what im saying!!
They are exactly the same. By the way, the standard unit is actually J kg^-1 K^-1 because a gram is not an SI unit. Chemists make is easier because they do mole calculations in grams as well. So the actual specific heat capacity of water is around 4.2^10*3 J kg^-1 K^-1
12. (Original post by mik1a)
They are exactly the same. By the way, the standard unit is actually J kg^-1 K^-1 because a gram is not an SI unit. Chemists make is easier because they do mole calculations in grams as well. So the actual specific heat capacity of water is around 4.2^10*3 J kg^-1 K^-1
Yes, read what mik1a is saying!
Anyway, I think it is given if it is needed for any calculations (on CCEA anyway.)

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