Chemistry gas law problem help?

Question

The volume of a gas at 273 degrees celcius is 200. liters. If the volume is decreased to 100. liters at constant pressure, what will be the new temperature of the gas?

please also show steps how to solve

Answer 1

Using the combined Charles & Boyles Laws equation

PV/T = pv/t
Being at constant pressure then P = p
PV/T = Pv/t
t = PvT/PV (NG the 'P's' cancel out).
t = vT/V
t = 100 x 273 / 200
t = 136.5 degrees C

Answer 2

The ideal gas law is:

PV=nRT

you should memorize this equation. Problems involving gases usually use this equation.

In our problem you see that one of the variables is being changed: "If the volume is decreased to 100." This should tell you that you need to use the following equation: (which is similiar to the ideal gas law. I remeber this equation from the ideal gas law.)

PV/T=PV/T

on the *left* hand side, we have the pressure, volume and temperature of the system *at the beginning*. So V = 200L and T = 273 C.

on the *right* and side of the equation you plug in the numbers of the system *at the end*. So V = 100L.

The pressure is constant, so you will drop it from the equation.

Plug in the values and solve for the missing value:

V/T = V/T

(200 L)/(273 C) = (100 L)/T
T*(200 L) = (100 L)*(273 C)
.
.
T = 1?? C

You should be able to solve the equation yourself. :)

It is a good habit to convert Celcius to Kelvin, but for this particular problem you don't need to.