Invisible Wall Precipitation Practical

Practical method

Use the tools in any order. Select a tool, then tap or drag inside the Petri dish.

Add potassium iodidePlace a small pile of white KI(s) on the left side.

Add lead(II) nitratePlace Pb(NO₃)₂(s) on the opposite side.

Add waterDraw a wet path between the two solids or add several drops.

Observe the reactionWatch the dissolved ions move and the yellow solid form.

Choose any tool to begin. Keep the two solids separated, then connect them with a wet path.

Tool: KI spatula · place on left

K⁺ potassium I⁻ iodide Pb²⁺ lead NO₃⁻ nitrate ● PbI₂(s)

Record your observation

Describe only what can be seen before explaining why it happened.

Student name

Both reactants began as white solids. A bright yellow solid formed in the wet region. A yellow solid remained in the wet region because lead(II) iodide is only sparingly soluble in water.

What is happening?

Reveal the equations after completing the practical.

Word equation

potassium iodide + lead(II) nitrate → lead(II) iodide + potassium nitrate

Full equation

2KI(aq) + Pb(NO₃)₂(aq) → PbI₂(s) + 2KNO₃(aq)

Net ionic equation

Pb²⁺(aq) + 2I⁻(aq) → PbI₂(s)

Spectator ions

K⁺(aq) and NO₃⁻(aq) remain dissolved and continue moving.

Check your understanding

Select one answer for each question.

1. Which observation is evidence that a precipitation reaction occurred?

2. Which ions combine to form the precipitate?

3. Why is water needed in this practical?

4. What happens to K⁺ and NO₃⁻ during the reaction?

Practical report

Export the current practical image, observation and quiz responses.

Enter a student name first. The report uses the current Petri dish view and the responses selected above.

Real practical safety: lead compounds are toxic. Wear eye protection and gloves, use microscale quantities, avoid skin contact, and collect all lead-containing waste as directed by the teacher. Do not wash it down the sink.