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Equations and formulae - EdexcelBalanced ionic equations - Higher

Chemists use symbols and formulae to represent elements, ions and compounds. Word equations and balanced chemical equations model the changes that happen in chemical reactions.

Part of Chemistry (Single Science)Key concepts in chemistry

Balanced ionic equations - Higher

A balanced shows the reacting in a chemical reaction. These equations can be used to model what happens in precipitation reactions.

Precipitation reactions

In a typical , two form an product and a soluble .

For example, silver nitrate solution reacts with sodium chloride solution. solid silver chloride and sodium nitrate solution form:

AgNO3(aq) + NaCl(aq) 鈫 AgCl(s) + NaNO3(aq)

The Na+ ions and NO3- ions remain separate in the sodium nitrate solution and do not form a . Ions that remain essentially unchanged during a reaction are called .This means you can ignore them when you write the ionic equation. You only need to model how the solid silver chloride forms:

Ag+(aq) + Cl-(aq) 鈫 AgCl(s)

In a balanced ionic equation:

  • the number of positive and negative is the same
  • the numbers of of each on the left and right are the same

Question

Explain why this ionic equation is balanced: Ba2+(aq) + SO42-(aq) 鈫 BaSO4(s)

Question

Balance this ionic equation, which models the formation of a silver carbonate precipitate: Ag+(aq) + CO32-(aq) 鈫 Ag2CO3(s)

Question

Balance this ionic equation, which models the formation of an aluminium hydroxide precipitate: __Al3+(aq) + __OH-(aq) 鈫 Al(OH)3(s)

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