Closed gas system

Question

A closed gas system initially has pressure and volume of 0.399atm and 1.20L with the temperature unknown. If the same closed system has values of 353torr, 3470mL and 642.0 oC, what was the initial temperature in oC?

Answer 1

This is a combined gas law. Make P units match, make V units match, make T units Kelvin, solve for T.

P1=0.399atm

V1=1.20L

T1=?

P2=353/760=0.46447 atm

V2=3470/1000=3.470L

T2=642.0C+273.15=915.15 K

P1V1/T1=P2V2/T2

^0.399(1.20)/_T1=^{0.46447(3.470)}/_915.15

T1=271.869 K

Convert from K to C:

TK=TC+273.15

271.869=TC+273.15

TC=271.869-273.15

T= −1.281 ^oC