C4 - Chemical
Calculations
, Conservation of mass and balancing equations
State symbols:
Balanced chemical equations sometimes include state symbols in brackets after each formula. They show
the physical state of that substance.
An aqueous solution forms when a substance dissolves in water.
State symbols are useful because they show what a substance is like. For example:
• H2O(l) is liquid water but H2O(g) is steam and H2O(s) is ice
• HCl(g) is hydrogen chloride gas but HCl(aq) is hydrochloric acid
Balancing equations:
A balanced chemical equation represents a chemical reaction using the formulae of the reactants and
products. It shows the number of units of each substance involved.
• The law of conservation of mass states that no atoms are lost or made during a chemical reaction so
the mass of the products equals the mass of the reactants.
• This means that chemical reactions can be represented by symbol equations which are balanced in
terms of the numbers of atoms of each element involved on both sides of the equation.
Calculations
, Conservation of mass and balancing equations
State symbols:
Balanced chemical equations sometimes include state symbols in brackets after each formula. They show
the physical state of that substance.
An aqueous solution forms when a substance dissolves in water.
State symbols are useful because they show what a substance is like. For example:
• H2O(l) is liquid water but H2O(g) is steam and H2O(s) is ice
• HCl(g) is hydrogen chloride gas but HCl(aq) is hydrochloric acid
Balancing equations:
A balanced chemical equation represents a chemical reaction using the formulae of the reactants and
products. It shows the number of units of each substance involved.
• The law of conservation of mass states that no atoms are lost or made during a chemical reaction so
the mass of the products equals the mass of the reactants.
• This means that chemical reactions can be represented by symbol equations which are balanced in
terms of the numbers of atoms of each element involved on both sides of the equation.
