Simple Gas Law Problem: Find Final Temperature

[swathi]

[SOLVED] Simple Grade 11 Question ! Help Please

A sample of natural gas occupies a volume of 350 L at 20.0 C. The pressure remains unchanged, and the temperature is increased until the volume of the natural gas becomes 385 L.

WHAT IS THE FINAL TEMPERATURE (in C) of the gas ?

easy question but i keep getting it wrong not sure why..
this is what i did..

V1 = 350 L
V2 = 385 L
T1 = 20 C ( or 293 Kevlin)
T2 = X (unknown... )

so i need the final temp..
i know the pressure is constant so that's Charles' law
V1/T1 = V2/T2

that's the formula i used and I'm not getting the right answer
:(
help would be greatly appreciated
=)

 

[mgb_phys]

First you have to use absolute temperature (kelvin)
Then think about what the answer should be.

You are increasing the volume of the gas so the molecules ar emore spread out. In order for them to have the same pressure, ie hit the walls as hard and as often, they must have more energy - so the temperature must be higher.

You are increasing the volume by around 5% so the absolute temperature should be around 5% higher. Now you can put the numbers into the calculator!

 

[swathi]

OMG !
wow that made so much sense
i got the right answer ! =)
stupid mistakee..
=) THANK YOU !