IBChemistryHLTopic QuestionsModels of the Particulate Nature of MatterCounting Particles by Mass: The Mole

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First teaching 2023

First exams 2025

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Counting Particles by Mass: The Mole (HL IB Chemistry)

Topic Questions

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Counting Particles by Mass: The Mole

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11 mark

A compound has an empirical formula of C2H6O and a molar mass of 92.16.

What is the molecular formula of this compound?

  • C2H6O 

  • C4H12O2

  • C6H18O3

  • C8H24O4

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21 mark

Ethane has the formula C2H6. What is the mass in grams of one molecule of ethane?

(RAMs: C = 12.0; H = 1.0)

  • 1.8 x 1025

  • 3.0 x 10-23

  • 30.0

  • 5.0 x 10-23

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31 mark

Shown below are four molecular formulas. Which one is also an empirical formula?

  • PCl5

  • CH3COOH

  • H2O2

  • C6H12O6

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41 mark

The relative atomic mass is a way of representing the mass of an atom.

Which of the following definitions is correct for the term relative atomic mass?

  • the mass of an electron

  • 1/12 the mass of a carbon-12 atom

  • the mass of a hydrogen-1 atom

  • the mass of a proton

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51 mark

Which of the following shows the relative formula mass of ammonium sulfate, (NH4)2SO4? 

  • 70.00

  • 132.00

  • 114.09

  • 132.17

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61 mark

Which amount of the following substances contains the smallest quantity of ions?

  • 2 mol of KOH  

  • 1 mol of NH4Br

  • 2 mol of MgCl2

  • 1 mol of Fe2O3

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71 mark

A sample of hydrated calcium sulfate, CaSO4∙xH2O, has a relative formula mass of 172.19

What is the value of x ?

  • 1

  • 2

  • 3

  • 4

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11 mark

A compound of molar mass 92 g mol-1 contains 12 g of carbon, 2 g of hydrogen and 32 g of oxygen. What is the molecular formula of the compound?

  • CH2O2

  • CH2O

  • C2H4O2

  • C2H4O4

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21 mark

Ethanoic acid has the formula CH3COOH. How many carbon atoms are present in
0.1 mol of ethanoic acid?

  • 6.0 x 1022

  • 1.2 x 1023

  • 6.0 x 1023

  • 1.2 x 1024

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31 mark

A compound contains carbon and hydrogen only. The amount of carbon is 80% by mass. What is the empirical formula of the compound?

                                             (RAMs, H = 1.01, C = 12.01)

  • CH

  • CH2

  • CH3

  • CH4

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41 mark

A hydrated carbonate of an unknown Group 1 metal has the formula X2CO3∙10H2O and is found to have a relative formula mass of 286.19                              

What is the Group 1 metal?

  • Rb

  • K

  • Na

  • Li

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51 mark

The diagram below shows the skeletal formula of phenazine.1-1-m-q9-ib-chemistry-mcqsWhat is the empirical formula of phenazine?

  • C6H6N

  • C12H8N2

  • C6H4N

  • C12H12N2

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61 mark

A coin contains 5.869% nickel by mass. If the coin weighs 10.00g, how many nickel atoms are in the coin?

  • 4.30 x 1022

  • 3.01 x 1023

  • 6.02 x 1025

  • 6.02 x 1021

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11 mark

10 cm3 of methane and 10 cm3 of ethane were sparked with an excess of oxygen. Once cooled, the remaining gas was passed through aqueous potassium hydroxide, which absorbs carbon dioxide.

Assume all measurements were taken at 25˚C and 1 atm pressure. 

What volume of gas is absorbed by the alkali?

  • 45 cm3

  • 30 cm3

  • 20 cm3

  • 10 cm3

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21 mark

Which sample contains the largest amount, in mol, of atoms?

  • 0.30 mol of P2O5

  •  0.40 mol of CuSO4.5H2O

  • 0.50 mol of CH3COOH

  • 0.90 mol of H2O

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31 mark

How many ions are present in 0.02 mol of (NH4)3PO4?

  • 8.0 x 10-2

  • 1.2 x 1022

  • 4.8 x 1022

  • 2.4 x 1023

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