Reversible Reactions — Ammonium Chloride
Heat it one way, cool it the other
NH4Cl (s) heat⟶ ⟵cool NH3 (g) + HCl (g)

Both gases are colourless. They are drawn as blue and green dots in the tube only so you can tell the two apart. In a real tube you see white fumes, which are tiny bits of solid ammonium chloride re-forming.

What was changedWhich way
Method
Temperature —
Solid at bottom —
Gas in tube —
Solid at top —
Step 1 of 3 — heat the solid
Accessibility — Adapt
Theme
Dark navy theme
Colour overlay (Irlen)
Off
Display
Reading ruler
Wider spacing (dyslexia)
Text size
115%
High contrast
Classroom / projector mode
Method checklistLists the three steps along the bottom and ticks them off as you go.
Meter readingsShows temperature and how much solid and gas there is, as large numbers in the footer.
Outline the apparatusDraws a dark edge round the stand and the burner so they stand out from the bench.
Label the directionPuts a card above the tube saying which way the reaction is going right now.
Show the gas particlesDraws the ammonia and hydrogen chloride as moving dots inside the tube.
Name the solidsLabels the white powder and the new white crystals with the compound name and formula.
Show the hot and cool zonesShades the hot bottom of the tube red and the cool top blue.
Procedure
Buttons onlyAdds a button for every action, so nothing has to be tapped in the 3D scene.
Extra slowStretches out the heating and the cooling, so there is longer to watch the change.
Motion & colour vision
Reduce motion
Slow animation
Auto-rotate camera
Protanopia
Deuteranopia