Testing for Ions and Gases · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Naming ions and gases at the bench

Science · Matter & Materials · ages 15-16
Name ______________________   Date ____________

  1. Acidified silver nitrate gives a cream precipitate. Which halide is present?

    • Chloride
    • Iodide
    • Bromide

  2. A sample burns with a lilac flame. Which ion is present?

    • Sodium
    • Potassium
    • Calcium

  3. Hydrogen relights a glowing splint.

    Circle one:   True   False

  4. Why does a flame test show a colour at all?

    • The metal boils and dyes the flame
    • Electrons drop shells to release light
    • Salt crystals scatter the burner light

  5. How do you test a solution for sulfate ions?

    • Add acidified barium chloride
    • Hold a lit splint to the sample
    • Add limewater and watch for it turning milky

  6. Which pair of results shows potassium chloride rather than sodium sulfate?

    • Yellow flame with no precipitate
    • Orange-red flame with milky limewater
    • Lilac flame plus a white precipitate with silver nitrate

  7. A white precipitate with acidified barium chloride proves a solution is potassium chloride.

    Circle one:   True   False

  8. A student calls a gas oxygen because a lit splint gives a pop. What is wrong?

    • The pop proves hydrogen, while oxygen relights a glowing splint
    • The pop proves carbon dioxide instead
    • Lit splints can never identify any gas
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Answer key

For grown-ups. Fold this page away before handing over the rest.

Naming ions and gases at the bench W1-mt_PDZjzQJdVt-s1

  1. Bromide · Cream silver bromide is the middle colour of the three halide precipitates.
  2. Potassium · Lilac is the flame colour of potassium.
  3. False · Relighting a glowing splint is the oxygen test. Hydrogen pops with a lit splint.
  4. Electrons drop shells to release light · Falling electrons release light of a set colour for each ion.
  5. Add acidified barium chloride · Sulfate with barium gives insoluble white barium sulfate.
  6. Lilac flame plus a white precipitate with silver nitrate · Lilac names potassium and the white precipitate names chloride.
  7. False · That precipitate points to sulfate, and it says nothing about potassium.
  8. The pop proves hydrogen, while oxygen relights a glowing splint · The pop is the hydrogen result, and the student used the wrong splint for oxygen.
Worksheet · LightMySky