# Question #7b5a1

##### 1 Answer

#### Explanation:

The key to this problem is the fact that the **pressure** and **temperature** of the gas sample remain **constant** before and after the chemical reaction takes place.

This means that you can use Avogadro's Law, which states that number of moles and volume have a **direct relationship** when temperature and pressure are kept constant.

In simple terms, when the number of moles of gas **increases**, the volume of the gas **increases** as well. Likewise, when the number of moles of gas **decreases**, the volume of the gas **decreases** as well.

Mathematically, this is written as

#color(blue)(V_1/n_1 = V_2/n_2)" "# , where

In your case, you know that you initially had *increased* by

#n_2 = 0.11 + 0.58 = "0.69 moles"#

This means that the new volume of the cylinder will be

#V_2 = n_2/n_1 * V_1#

#V_2 = (0.69color(red)(cancel(color(black)("moles"))))/(0.11color(red)(cancel(color(black)("moles")))) * "2.1 L"#

#V_2 = "13.17 L"#

Rounded to two sig figs, the number of sig figs you have for the values given, the answer will be

#V_2 = color(green)("13 L")#