OmniLab Observation guide

For chemistry students · 4 minute read

What happens when aluminium chloride reacts with sodium hydroxide?

Aqueous aluminium chloride and sodium hydroxide can form a white aluminium hydroxide precipitate. Excess hydroxide can dissolve that solid.

Balanced equation
AlCl3(aq) + 3NaOH(aq) -> Al(OH)3(s) + 3NaCl(aq)
Model and safety boundary
OmniLab shows the precipitation stage only. Adding more sodium hydroxide in the browser does not model redissolving the solid.

Your study goal: Separate the first white precipitate from its later behavior in excess alkali.

Open the prepared example

The exact supported pair opens in a beaker. Nothing runs until you select Analyze.

The OmniLab virtual chemistry workspace with a beaker area and reaction analysis panel
Prepared beaker
AlCl3 NaOH
Burner off · Analysis waits for you
The supported pair is prepared in a beaker. Analysis waits for you.

Supported prediction

AlCl3(aq) + 3NaOH(aq) -> Al(OH)3(s) + 3NaCl(aq)

What the equation means

Aluminum chloride and sodium hydroxide form a white aluminum hydroxide precipitate while sodium chloride remains in solution. Three hydroxide ions are required for each aluminum ion. Excess hydroxide can redissolve the amphoteric precipitate.

Expected observation

A white solid, with an important excess-alkali limit

The initial precipitate can look white and gelatinous. In a real solution, sufficient excess hydroxide can dissolve it. OmniLab keeps a simplified white precipitate cue and does not model that second stage.

Net ionic equation

Which ions actually form the precipitate?

Aluminium ions combine with hydroxide ions to form the solid. Hydration details are omitted from this classroom ionic equation.

Particles that change Al3+(aq) + 3OH-(aq) -> Al(OH)3(s)

Spectator ions: Na+(aq) and Cl-(aq) remain dissolved during the precipitation stage.

  1. 01

    Balance the ion charges

    One Al3+ ion has charge +3. Three OH- ions supply charge -3, giving a neutral solid.

  2. 02

    Keep spectators in solution

    Sodium and chloride ions appear on both sides of the complete ionic equation. Cancel them to show the change that forms the solid.

  3. 03

    Distinguish the second stage

    Aluminium hydroxide can react with excess hydroxide to form dissolved [Al(OH)4]- ions. That stage is outside this prepared result.

Three safety notes

Read these before any physical experiment

  1. 01

    Wear chemical splash goggles and alkali-resistant gloves.

  2. 02

    Add dilute sodium hydroxide dropwise to avoid excess base.

  3. 03

    Rinse chemical splashes immediately with plenty of water.

Common questions

What students usually ask next

Use these distinctions to move from the visible reaction to the particle-level explanation.

What is the white precipitate?

It is aluminium hydroxide, Al(OH)3. The chloride and sodium ions stay dissolved during its formation.

What does amphoteric mean here?

Aluminium hydroxide reacts with both acids and bases. Its dissolution in excess hydroxide demonstrates its reaction with a base.

What equation describes excess hydroxide?

A common aqueous summary is Al(OH)3(s) + OH-(aq) -> [Al(OH)4]-(aq). This is a separate stage, not OmniLab's returned equation.

Will the browser solid disappear in excess alkali?

No. The model recognizes the selected pair, but it does not calculate amounts or complex-ion equilibria.

Keep exploring

Connect this observation to another reaction

These guides use the same pattern: predict the equation, identify the visible cue, then check what the virtual model leaves out.

See how the full virtual lab works