# Question #4cfd2

##### 3 Answers

- The density of argon is 1.57 g/L.

#### Explanation:

We can use the Ideal Gas Law to solve this problem.

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

Since

#PV = (m/M)RT#

We can rearrange this to

#PM = m/VRT#

But

∴

and

#color(brown)(bar(ul(|color(white)(a/a)ρ = (PM)/(RT)color(white)(a/a)|)))" "#

In your problem,

∴

**2.** The value of

**STP** is defined as a pressure of exactly 1 bar (

At STP the volume of 1 mol of an ideal gas is 22.71 L (

The Ideal Gas Law is

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

We can rearrange this to get

#R = (PV)/(nT)#

∴

**3.** You will need 15.0 L of

#### Explanation:

For this problem, we can use **Gay-Lussac's Law of Combining Volumes**:

If pressure and temperature are constant, the ratio between the volumes of the reactant gases and the products can be expressed in simple whole numbers.

The balanced equation for the reaction is

#color(white)(ll)"N"_2 + "3H"_2 → "2NH"_3#

#color(white)(ll)"1 L"color(white)(ml)"3 L"#

According to Gay-Lussac,

∴