Question

Question #ba20f

Answer 1

It depends on whether the element is a gas or a liquid.

It looks as if you are trying to use the molar mass to convert grams or moles of an element to litres of the element.

1. If the element is a gas

Method 1

You convert grams to moles and then use the Ideal Gas Law to find the volume.

Example 1: What is the volume of 10.0 g of chlorine gas at 1.00 atm and 25°C?

Moles of chlorine = 10.0 g Cl₂ × `("1 mol Cl"_2)/("70.91 g Cl"_2)` = 0.1410 mol Cl₂

The Ideal Gas Law is `PV = nRT` so

`V = (nRT)/P = ("0.1410 mol × 0.082 06 L·atm·K"^-1"mol"^-1 × "298.15 K")/"1 atm"` =3.45 L

Example 2: What is the volume of 0.150 mol of chlorine gas if its density is 2.90 g/L at 1.00 atm and 25°C?

Here you can convert moles to grams, and then use the density to find the volume.

0.150 mol Cl₂ × `("70.91 g Cl"_2)/("1 mol Cl"_2)` = 10.64 g Cl₂

10.64 g Cl₂ × `("1 L Cl"_2)/("2.90 g Cl"_2)` = 3.67 L Cl₂

2. If the element is a liquid

Example 3. What is the volume of 6.25 mol of bromine? The density is 3.12 g/mL.

6.25 mol Br₂ × `("159.81 g Br"_2)/("1 mol Br"_2) × ("1 mL Br"_2)/("3.12 g Br"_2) × ("1 L Br"_2)/("1000 mL Br"_2)` = 0.320 L Br₂