Half Equations Flashcards

1️⃣ Familiarise yourself with the flashcards:

  • Look through all the flashcards to see what's on both sides.
  • Make sure you understand the information on each card. If something's unclear, click the link to the revision notes at the bottom of the page for more details.

2️⃣ Test yourself:

  • Look at the question or prompt on each card and try to remember the answer before flipping it over.
  • Check the answer and make a note of any cards you find challenging and need to go over more.

3️⃣ Consistently Review and Practice:

  • Use spaced repetition: spend more time on the cards you struggle with and go over them more often.
  • Regularly review all the flashcards to help you better understand and retain the information over time.

Note: We may include questions that have multiple correct answers. It's useful to remember specific examples to understand these concepts better.

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In electrolysis, what is a half equation?

A half equation is a chemical equation that shows what happens at one electrode, including the electrons.

What does a half equation always include that a normal word equation does not?

A half equation always includes electrons, shown by the symbol e⁻.

In terms of electrons, what is oxidation?

Oxidation is the loss of electrons by a particle.

In terms of electrons, what is reduction?

Reduction is the gain of electrons by a particle.

In a reduction half equation, on which side do the electrons appear?

In a reduction half equation, the electrons are written on the left-hand side.

In an oxidation half equation, on which side do the electrons appear?

In an oxidation half equation, the electrons are written on the right-hand side.

Write the half equation for a copper ion, Cu²⁺, gaining two electrons to form copper metal.

Cu²⁺ + 2e⁻ -> Cu

Write the half equation for two chloride ions, Cl⁻, forming chlorine gas and electrons.

2Cl⁻ -> Cl₂ + 2e⁻

How can you check if a half equation is balanced?

Check that the number of each type of atom and the total charge are the same on both sides.

How do you get the overall ionic equation from two half equations?

You add the two half equations together and cancel out the electrons on each side.

Why do half equations not include spectator ions?

Spectator ions are not shown because they do not gain or lose electrons and do not change in the reaction.

Why are half equations useful in electrolysis?

They help you see which ions are oxidised or reduced and predict the products at each electrode.

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