More Lessons for Chemistry

Math Worksheets

- An amount of substance containing 6.02 × 10
^{23}particles is called a**mole**(often abbreviated to mol). - 6.02 × 10
^{23}is called the**Avogadro constant**.

*Example: *

One mole of carbon contains 6.02 × 10^{23} of carbon atoms

One mole of oxygen contains 6.02 × 10^{23} of oxygen molecules

- The mass of one mole of a substance is called the
**molar mass**.

- The molar mass of a substance is equal to its relative formula mass in grams.

*Example: *

What is the mass of 1 mole of carbon?

*Solution: *

The mass of 1 mole of carbon = relative formula mass of carbon = 12 grams

*Example: *

What is the molar mass of calcium carbonate (CaCO_{3})?

*Solution: *

**Step 1:** Look up the relative atomic masses of the atoms from the periodic table.

Relative atomic mass (rounded to the nearest whole number):

Ca = 40, C = 12, O = 16

**Step 2: **Calculate the relative formula mass.

Calcium carbonate (CaCO_{3}) contains one calcium atom, one carbon atom and three oxygen atoms.

Relative formula mass = 40 + 12 + (3 × 16) = 100

**Step 3: **Express the relative formula mass in grams per mole.

The molar mass of ethanol is 100 g/mol

*Example: *

What is the molar mass of ethanol (C_{2}H_{5}OH)?

*Solution: *

**Step 1: **Look up the relative atomic masses of the atoms from the periodic table.

Relative atomic mass (rounded to the nearest whole number):

H = 1, C = 12, O = 16

**Step 2: **Calculate the relative formula mass.

Ethanol (C_{2}H_{5}OH) contains two carbon atoms, six hydrogen atoms and one oxygen atom.

Relative formula mass = (2 × 12) + (6 × 1) + 16 = 46

**Step 3: **Express the relative formula mass in grams per mole.

The molar mass of ethanol is 46 g/mol

Avogadro's gas law, Avogadro's number, the MOLE and molar mass.

Rotate to landscape screen format on a mobile phone or small tablet to use the **Mathway** widget, a free math problem solver that **answers your questions with step-by-step explanations**.

You can use the free Mathway calculator and problem solver below to practice Algebra or other math topics. Try the given examples, or type in your own problem and check your answer with the step-by-step explanations.