# Question #c5367

##### 1 Answer

#### Answer:

The volume of hydrogen would be 7.47 L.

#### Explanation:

There are four steps involved in this problem:

- Write the
**balanced equation**for the reaction. - Use the
**molar mass**of#"Mg"# to calculate the moles of#"Mg"# . - Use the
**molar ratio**of#"Mg":"H"_2# from the balanced equation to calculate the moles of#"H"_2# . - Use the
**Ideal Gas Law**to calculate the volume of#"H"_2# at STP.

**Step 1. Write the balanced chemical equation.**

**Step 2. Calculate the moles of #"Mg"#.**

**Step 3. Calculate the moles of #"H"_2#**

**Step 4. Calculate the volume of #"H"_2#**

The **Ideal Gas Law** is

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

We can rearrange this equation to get

#V = (nRT)/P#

STP is defined as 1 bar and 0 °C, so

∴