This document provides an introduction to stoichiometry and calculations involving moles. It defines key terms like relative atomic mass, molar mass, mole, and Avogadro's constant. It presents methods for converting between mass and moles using molar mass. Examples demonstrate calculating moles from mass and mass from moles for various compounds. The document also shows reacting mass calculations involving moles.

1. MOLES/CHEMISTRY/IGCSE 2016-17
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Stoichiometry
Calculationsinvolvingthe mol
Learning Objectives:
By the end of the lesson you should be able to the
following:
Y ? N
Define relative atomic mass, Ar
Define relative formula mass or Molar mass, as the sum of
the relative atomic masses (relative formula mass or Mr will
be used for ionic compounds)
Define the mol
Define the Avogadro constant
Manipulate the formula triangle to convert between mol and
mass of substances
Complete the following table defining the following terms:
Relative Atomic Mass
Relative Formula Mass
Mass
Molar Mass
Avogadro’s constant
Mole (Mol)
Just how big is Avogadro’s constant…one mole of sand grains would cover Britain to a depth
of 1500 km!
Chemistry (0620)
Name: .................................
Date.............................

2. MOLES/CHEMISTRY/IGCSE 2016-17
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No, not this furry character!
INTRODUCING THE MOL
Mol is the unit used by all chemists to calculate the amount of substance
1 mol of a substance contains 6.02x1023 particles
For example there are 6.02x1023 atoms in 12.0g of Carbon.
How many atoms in 6.0g of Carbon?
The number 6.02x1023 is very large and is named after the Italian chemist Amedeo
Avogadro it is otherwise known as Avogadro’s constant.
Try the following questions:-
1. How many particles in 1.mol of Magnesium
2. What is the number of mol in 12g of Magnesium?
3. What is the number of mol in 36g of Magnesium?

3. MOLES/CHEMISTRY/IGCSE 2016-17
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OPENING NEW HORIZONS…CONVERTING MASS TO MOLES
Calculating number of moles of solid substances
CALCULATE THE RELATIVE FORMULA MASS OF EACH THE FOLOLOWING
SUBSTANCES REMEMBER YOUR UNITS IN EACH CASE
Calcium carbonate
Formula:
Sodium Hydroxide
Formula:
Silicon Dioxide
Formula:
Sulphur trioxide
Formula:
Nitric acid
Formula:
Carbon dioxide
Formula:
Magnesium oxide
Formula:
Potassium Bromide
Formula:
Barium Chloride
Formula:
Oxygen molecule
Formula:
Aluminium Nitride
Formula:
Calcium Oxide
Formula:
Copper Sulphide
Formula:
Potassium Manganate (VII)
Formula:
Sodium Dichromate (VI)
Formula:

4. MOLES/CHEMISTRY/IGCSE 2016-17
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GOING FOR THE BORDER…CONVERTING MASS TO MOLES
This is the method for the calculation:
Stage 1: Calculate the relative formula mass substance (This is equal to 1 mol)
Stage 2: Calculate the number of moles of the substance; by dividing the mass
present by the relative formula mass of the substance.
Stage 3: Present your answer to 3 significant figures.
Question 1 28.3g of NaCl
Stage 1
Stage 2
Answer
Question 2 45.6g of LiNO3
Stage 1
Stage 2
Answer
Question 3 235.8g of BaCl2
Stage 1
Stage 2
Answer

5. MOLES/CHEMISTRY/IGCSE 2016-17
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GOING FOR THE BORDER…CONVERTING MOLES TO MASS
This is the method for the calculation:
Stage 1: Calculate the relative formula mass of the substance (This is equal to 1
mol)
Stage 2: Calculate the mass of the compound; by multiplying the number of moles
by the relative formula mass of the compound
Stage 3: Present your answer to 3 significant figures.
Question 1 0.5mol of NaCl
Stage 1
Stage 2
Answer
Question 2 4.6mol of LiNO3
Stage 1
Stage 2
Answer
Question 3 2.00mol of BaCl2
Stage 1
Stage 2
Answer

6. MOLES/CHEMISTRY/IGCSE 2016-17
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Calculate the moles in each of the following substances, write down your
method for each one:
1. How many moles of Na are there in 42 g of Na?
2. How many moles of O are there in 8.25 g of O?
3. How many moles of O2 are in 8.25 g of O2
4. What is the mass of 0.28 mol of Iron?
5. How many atoms are in 7.2 mol of chlorine?
6. How many atoms are in 36 g of bromine?
7. How many moles of CO molecules are in 52 g of CO?
8. How many moles of C2H6 are in 124 g?

7. MOLES/CHEMISTRY/IGCSE 2016-17
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Calculations involving reacting masses
Considering the diagram what is the mass of O2 required to form 2 moles of water?
1) What mass of carbon dioxide is formed when 20 g of calcium carbonate reacts
with hydrochloric acid?
CaCO3 + 2 HCl  CaCl2 + H2O + CO2 (3)
2) What mass of oxygen reacts with 192 g of magnesium?
2 Mg + O2  2 MgO (3)
3) What mass of carbon monoxide is needed to react with 100g of iron oxide?
Fe2O3 + 3 CO  2 Fe + 3 CO2 (3)
4) What mass of oxygen is needed to react with 184 g of sodium?
4 Na + O2  2 Na2O (3)

8. MOLES/CHEMISTRY/IGCSE 2016-17
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Home assignment…
Thinking outside the box
Question 1 Calculate the mass in 0.5mol of CaCl2
Stage 1
Stage 2
Answer
Question 1 Calculate the mass in 0.1mol of KBr
Stage 1
Stage 2
Answer
Question 1 Calculate the number of moles present in 316.0g of
KMnO4
Stage 1
Stage 2
Answer
Question 1 Calculate the number of moles present in 500.0g of
Pentahydrate Copper Sulphate (Sulphate/Sulfate)
Stage 1
Stage 2
Answer
Chemistry (0620)
Name:.....................
Date........................
Homework
Mark %
To improve

9. MOLES/CHEMISTRY/IGCSE 2016-17
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1. How many molecules are there in 52 g of CO?
2. How many molecules are there in 116 g of CCl4?
3. What do you think are the most important steps in a reacting mass calculation
involving the moles? Put it into your own words:
:
Stage 1: Stage 2:
Stage 3: Stage 4:
Use your ideas to answer each of the following questions:
1. Calculate mass of sodium carbonate is formed when 8.4 g of sodium hydrogen
carbonate (NaHCO3) is decomposed by heat?
2 NaHCO3  Na2CO3 + H2O + CO2
2. Calculate mass of calcium carbonate is needed to form 88g of carbon dioxide?
CaCO3(s)  CaO(s)+ CO2(g)
3. Calculate mass of ammonia can be made from 20 g of hydrogen?
3H2 + N2 → 2 NH3
.. .. ..

10. MOLES/CHEMISTRY/IGCSE 2016-17
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4. Calculate the mass of sodium hydroxide which will react with 9.8 g of sulphuric
acid?
H2SO4 + 2 NaOH → Na2SO4 + 2 H2O
5. Calculate the mass of chlorine which will react with 20 g of iron to form iron (III)
chloride?
2 Fe + 3 Cl2 → 2 FeCl3 ..
.. ..
.. .. ..