Practice Mole in Chemistry

Use these practice problems to test your method after reviewing the concept explanation and worked examples.

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Quick Recap

The fundamental counting unit in chemistry, defined as exactly 6.022×10236.022 \times 10^{23} particles (atoms, molecules, ions, or other entities).

A 'chemist's dozen'—a huge number that makes atom-counting practical.

Showing a random 20 of 50 problems.

Example 1

medium
Order by particle count: 1 mol HeHe, 0.5 mol O2O_2, 2 mol HH atoms.

Example 2

medium
How many particles are in 0.05 mol0.05\,\text{mol}?

Example 3

easy
How many particles are in 0.10 mol0.10\,\text{mol} of Cl2\text{Cl}_2 molecules?

Example 4

easy
How many moles are in 3.011×10243.011 \times 10^{24} atoms of carbon?

Example 5

challenge
Two samples have equal particle counts: sample A is HeHe, sample B is CH4CH_4. If A is 0.50.5 mol, how many molecules does B have?

Example 6

easy
A sample contains 0.50.5 mol of a substance. How many particles is that?

Example 7

medium
How many moles is 9.033×10239.033 \times 10^{23} molecules of CO2CO_2?

Example 8

medium
How many moles of HH atoms are in 3 moles of NH3NH_3?

Example 9

easy
How many moles of atoms are in 4 moles of O2O_2 molecules?

Example 10

easy
A sample contains 1.204×10241.204 \times 10^{24} molecules of ammonia. How many moles of NH3\text{NH}_3 is this?

Example 11

challenge
A sealed bulb at STP contains 1.12 L1.12\,\text{L} of a mixture that is 25%25\% N2\text{N}_2 and 75%75\% O2\text{O}_2 by volume. How many total atoms are in the bulb? (Vm=22.4 L/molV_m = 22.4\,\text{L/mol})

Example 12

challenge
How many total atoms are in 0.250.25 mol of Ca(OH)2Ca(OH)_2?

Example 13

medium
If 1 mol AlAl weighs 27 g27\text{ g}, how many atoms are in 54 g54\text{ g} of AlAl?

Example 14

hard
How many chloride ions are released when 0.1 mol0.1\,\text{mol} of CaCl2\text{CaCl}_2 dissolves fully in water?

Example 15

easy
What is a mole and why is it useful in chemistry?

Example 16

medium
At STP, how many moles of an ideal gas occupy 44.8 L44.8\,\text{L}? (Vm=22.4 L/molV_m = 22.4\,\text{L/mol})

Example 17

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How many moles of water are in 36.036.0 g of H2O\text{H}_2\text{O}? (Molar mass of H2O=18.0 g/mol\text{H}_2\text{O} = 18.0\,\text{g/mol})

Example 18

medium
How many oxygen atoms are in 0.50 mol0.50\,\text{mol} of glucose (C6H12O6\text{C}_6\text{H}_{12}\text{O}_6)?

Example 19

easy
Is '1 mole of oxygen' fully specified? Why or why not?

Example 20

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How many sodium ions are in 0.20 mol0.20\,\text{mol} of Na2SO4\text{Na}_2\text{SO}_4?
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