# A 3.50-L gas sample at 20°C and a pressure of 86.7 kPa expands to a volume of 8.00 L. The final pressure of the gas is 56.7 kPa. What is the final temperature of the gas, in degrees Celsius?

##### 1 Answer

#### Explanation:

We can use here the *combined gas law*, relating the temperature, pressure, and volume of a gas with a constant quantity:

If you're using the ideal-gas equation, which we're NOT using here, you would have to convert each measurement into the appropriate units (**always** convert temperature to Kelvin (absolute temperature) when using gas equations).

The Kelvin temperature is

Let's rearrange the combined gas law to solve for the final temperature,

Plugging in known values, we can find the final temperature:

Lastly, we'll convert back from