3 Stoichiometry
Note - ‘Quote this’ refers to quoting the syllabus dot point
3.1 Formulae
Core
1 State the formulae of the elements and compounds named in the subject content
Exam note
Memorise the following formulas
Sulfate
Nitrate
Hydroxide
Phosphate
Carbonate
Ammonium
Sulfuric acid
Nitric acid
2. Define the molecular formula of a compound as the number and type of different atoms in
one molecule
Quote this
Extra notes
E.g H20
The subscript of 2 shows that are are 2 hydrogen atoms in a molecule of water
3 Deduce the formula of a simple compound from the relative numbers of atoms present in a
model or a diagrammatic representation
If you get shown a molecule of water, for example, you need to be able to write its formula
4 Construct word equations and symbol equations to show how reactants form products,
including state symbols
Reactants are on the left, products are on the right. Instead of using an equal sign, use an
arrow. If there are conditions like photosynthesis, where it has to be in sunlight, put it above
the arrow (hard to format, so it isn’t shown below)
Word equation
Carbon dioxide + water → glucose + oxygen
, Symbol equation
6Co2 + 6H20 → C6H12O6 + 6O2
Supplement
5 Define the empirical formula of a compound as the simplest whole number ratio of the
different atoms or ions in a compound
+
7 Calculate empirical formulae and molecular formulae, given appropriate data
Quote this
Extra notes
E.g
The molecular formula of glucose is C6H12O6, but its empirical formula would be CH2O
6 Deduce the formula of an ionic compound from the relative numbers of the ions present in
a model or a diagrammatic representation, or from the charges on the ions
Swap each element compound's charge with each other, and turn them into their subscripts.
E.g
Mg2+ and Cl-
It becomes MgCl2
7 Construct symbol equations with state symbols, including ionic equations
HCL(aq) + NaOH → NaCl(aq) + H20(l)
Solids -s
Liquids - l
Gases -g
Aqueous - aq
Exam Notes
Acids and bases are usually aq
Water is the most commonly used liquid
8 Deduce the symbol equation with state symbols for a chemical reaction, given relevant
Information
Practice word questions
E.g
Magnesium reacts with oxygen to form the white solid magnesium oxide. Write the balanced
symbol equation, including state symbols, for the reaction.
Note - ‘Quote this’ refers to quoting the syllabus dot point
3.1 Formulae
Core
1 State the formulae of the elements and compounds named in the subject content
Exam note
Memorise the following formulas
Sulfate
Nitrate
Hydroxide
Phosphate
Carbonate
Ammonium
Sulfuric acid
Nitric acid
2. Define the molecular formula of a compound as the number and type of different atoms in
one molecule
Quote this
Extra notes
E.g H20
The subscript of 2 shows that are are 2 hydrogen atoms in a molecule of water
3 Deduce the formula of a simple compound from the relative numbers of atoms present in a
model or a diagrammatic representation
If you get shown a molecule of water, for example, you need to be able to write its formula
4 Construct word equations and symbol equations to show how reactants form products,
including state symbols
Reactants are on the left, products are on the right. Instead of using an equal sign, use an
arrow. If there are conditions like photosynthesis, where it has to be in sunlight, put it above
the arrow (hard to format, so it isn’t shown below)
Word equation
Carbon dioxide + water → glucose + oxygen
, Symbol equation
6Co2 + 6H20 → C6H12O6 + 6O2
Supplement
5 Define the empirical formula of a compound as the simplest whole number ratio of the
different atoms or ions in a compound
+
7 Calculate empirical formulae and molecular formulae, given appropriate data
Quote this
Extra notes
E.g
The molecular formula of glucose is C6H12O6, but its empirical formula would be CH2O
6 Deduce the formula of an ionic compound from the relative numbers of the ions present in
a model or a diagrammatic representation, or from the charges on the ions
Swap each element compound's charge with each other, and turn them into their subscripts.
E.g
Mg2+ and Cl-
It becomes MgCl2
7 Construct symbol equations with state symbols, including ionic equations
HCL(aq) + NaOH → NaCl(aq) + H20(l)
Solids -s
Liquids - l
Gases -g
Aqueous - aq
Exam Notes
Acids and bases are usually aq
Water is the most commonly used liquid
8 Deduce the symbol equation with state symbols for a chemical reaction, given relevant
Information
Practice word questions
E.g
Magnesium reacts with oxygen to form the white solid magnesium oxide. Write the balanced
symbol equation, including state symbols, for the reaction.
