Question

A gas has a volume of 350 mL at 45°C. If the volume changes to 400 mL, what is the new temperature?

Answer 1

28°C.

Explanation:

The correct equation to use with these kinds of questions is the Combined Gas Law.

`(P_1*V_1)/T_1 = (P_2*V_2)/T_2`

This equation, though, is a little unnecessary at times because of the possibility of extra constants.

In this case you have a pressure constant which enables us to shorten your longer equation down to Charles' Law because pressure remains the same and doesn't affect the calculation.

`(V_1)/T_1 = (V_2)/T_2`

The next step is to isolate the variable that you want, which is, in this case, `T_2`.

`T_2 = (V_1T_1)/V_2`

Now it is time to replace your known variables with numbers

`T_2 = (350mL*45°C)/(400mL)`

And calculate...

`T_2 = 28.125°C`

Significant digits...

`T_2 = 28°C`