# How do you find the number of moles for a gas from temperature and pressure?

##### 1 Answer

You use the Ideal Gas Law.

#### Explanation:

You also need the volume.

Then, you insert the pressure, volume, and temperature into the expression and calculate the number of moles.

The Ideal Gas Law is

#color(blue)(bar(ul(|color(white)(a/a)pV = nRTcolor(white)(a/a)|)))" "#

We can rearrange this formula to get the number of moles,

#n = (pV)/(RT)#

**EXAMPLE**

A 3.00 L container is filled with neon gas at 770 mmHg and 27 °C. How many moles of neon are present?

**Solution**

**Step 1.** List the information given, making conversions as necessary.

**Step 2.** Calculate the number of moles.

There are 0.123 mol of neon in the container.