A sample of a gas occupies 1810 mL at 319◦C and 740 torr. At what temperature would it occupy 1586.8 mL if the pressure is kept constant? Answer in units of ◦C.

Answer 1

1. Use V1/T1 = V2/T2
2. V1 = 1810 mL
3. T1 = 319
4. V2 = 1586.6
5. T2= unknown
6. Remember that in order to use gas laws, you must convert temperature to K (C + 273 = K)
7. Convert T value to Kelvin, then solve algebraically
8. (1810/319+273) = (1586.6/T)
9. use butterfly method to cross multiply and then simplify 1810T = 939267.2
10. divide both sides by 1810
11. t =518.93 K
12. Convert 2.8829K to degrees celsius by substracting 273
13. 518.93-273 = 246 degrees C

Answer 2

Come on, Sophia P.,

Convert temperature to degrees K, solve as a gas law ratio, and convert back to degrees C.

You should be able to do this even when half asleep. If you need practice in setting up ratios quickly, get a peer to pose you questions on it. When test time comes, it needs to be about automatic.

--Cheers, --Mr. d.