Domain: Natural Science — Chemistry
Target concept: Detection of Copper Ions in Malachite Green (Ammonia Color Development Method)

Video generation prompt: Place malachite powder in a test tube, add 2 drops of dilute hydrochloric acid to dissolve it, then add 3 drops of ammonia solution.

Evaluation guide:
(i) Target concept: Visual verification of copper ion detection via ammonia-induced color development in malachite (the natural basic copper carbonate mineral, Cu₂CO₃(OH)₂, not the unrelated synthetic dye that also goes by the common name "malachite green").
Minimum mechanism: Copper(II) must be released into solution by acid dissolution of the carbonate mineral (a process that also releases visible CO₂ gas bubbles) *before* ammonia can coordinate and generate the diagnostic deep blue-violet [Cu(NH₃)₄]²⁺ color; no direct solid-state reaction occurs.
(ii)Storyline: Frame 1–2: Green powder placed inside upright test tube (fixed frontal view). Frame 3–5: Two distinct acid droplets descend and contact the powder → the powder dissolves with brief visible gas bubbling (CO₂), clearing into a transparent pale-blue or colorless liquid once the bubbling subsides, with no green residue left. Frame 6–8: Three distinct ammonia droplets descend and contact the liquid → rapid, uniform color transition to deep blue-violet across the entire liquid volume. Throughout: test tube remains motionless; lighting stable; no occlusion; all actions occur within the same continuous shot from a fixed viewpoint.

Manual:
Experimental Procedure
1. Place malachite powder (the natural basic copper carbonate mineral, Cu₂CO₃(OH)₂ — distinct from the unrelated synthetic dye sometimes also called "malachite green") in a clean, dry test tube.
2. Add 2 drops of dilute hydrochloric acid — the powder dissolves completely, with brief visible gas bubbling as CO₂ is released.
3. Add 3 drops of ammonia solution — the solution turns deep blue-violet.
Observation of Experimental Phenomena
- The green solid dissolves upon acid addition, releasing small CO₂ gas bubbles, and forms a clear pale-blue or colorless solution once the bubbling stops.
- Upon ammonia addition, the solution turns uniformly deep blue-violet, characteristic of the [Cu(NH₃)₄]²⁺ complex.
Summary of Experimental Principles
Malachite is a basic copper carbonate mineral, Cu₂CO₃(OH)₂, containing copper(II) ions. Dilute HCl dissolves it via Cu₂CO₃(OH)₂ + 4HCl → 2CuCl₂ + 3H₂O + CO₂↑, releasing Cu²⁺ into solution together with visible CO₂ bubbling; NH₃ then coordinates with Cu²⁺ to form the intensely colored tetraamminecopper(II) complex, [Cu(NH₃)₄]²⁺.

Prompt Grounding rubric:
level_1: No test tube is shown; or no green malachite powder is visible; or neither an acid dropper/applicator nor an ammonia dropper/applicator appears; or none of the three actions (placing the powder, adding acid, adding ammonia) is depicted.
level_2: A test tube with green powder is shown, but at least two of the following are missing: a dropper visibly delivering hydrochloric acid onto the powder; a dropper visibly delivering ammonia into the resulting liquid; the acid addition occurring before the ammonia addition.
level_3: A test tube holding green malachite powder, a dropper delivering acid onto the powder, and a second dropper delivering ammonia into the tube's liquid all appear in one continuous scene from a fixed viewpoint, with the acid step shown before the ammonia step.
level_4: Everything required for the 3-point level is shown, and in addition the acid and the ammonia are each delivered as distinguishable individual drops rather than a continuous pour or an indistinct smear, the powder and liquid stay confined inside the test tube throughout, and no unrelated object (hand, glove, label, second container) blocks the view of either addition.
level_5: Everything required for the 4-point level is shown, and in addition a viewer can count exactly two acid drops and exactly three ammonia drops landing inside the tube, no drop misses the tube or splashes outside it, the powder is placed before the first acid drop appears, and the tube, both droppers, and the liquid inside stay fully visible in the same relative position from the first frame to the last.

Scientific and Causal Correctness rubric:
level_1: The liquid's color never changes throughout the clip; or the green powder fails to dissolve when acid is added; or the liquid ends up red, brown, black, or unchanged green rather than blue-violet; or a blue-violet color appears before any ammonia is added.
level_2: The green powder partly breaks apart with acid but never clears into a transparent liquid; or a clear liquid forms but stays green or colorless after ammonia is added; or the color that appears after ammonia is not the expected deep blue-violet (e.g., pale blue, muddy brown, or grey).
level_3: Adding acid dissolves the green powder (brief gas bubbling from the carbonate reacting with the acid may be visible during this step), leaving a clear, pale-blue-to-colorless liquid with no green solid remaining; adding ammonia then turns this liquid a uniform deep blue-violet, and the color neither fades nor reverses for the rest of the clip.
level_4: Everything required for the 3-point level holds, and in addition the blue-violet that appears after ammonia is clearly more saturated than the pale-blue liquid before it, the blue-violet fills essentially the entire liquid column rather than sitting in streaks or a partial layer, and no leftover green specks remain once the acid step has finished.
level_5: Everything required for the 4-point level holds, and in addition any bubbling from the acid step has settled before the first ammonia drop touches the liquid, the color begins shifting toward blue-violet as soon as an ammonia drop lands and reaches its final shade before the next drop lands, and the finished blue-violet liquid looks the same shade from top to bottom with no separate layer or film on the surface.

Spatiotemporal Consistency rubric:
level_1: The test tube appears or disappears without ever being carried into or out of frame; a drop appears already touching the powder or liquid with no visible fall; the powder is inside the tube in one frame with no placement action shown before it; the lighting on the scene jumps to a different level between two consecutive frames with no dropper action or camera move to explain it; or the test tube rotates more than about 45 degrees or flips upside down with no visible motion causing it.
level_2: The tube stays on screen but visibly jumps in size (a change of more than roughly 10%) or position between frames; a falling drop's position skips rather than moving smoothly along its path; the direction of the light and shadow on the tube swaps sides partway through the clip with nothing in the scene (a new drop, a camera move) to explain the change; or background elements behind the tube flicker or warp during the action.
level_3: The test tube stays in the same place, orientation, and size throughout; each acid and ammonia drop falls along a smooth, continuous path into the tube; the direction and brightness of the lighting on the tube stay the same from the first frame to the last, aside from the liquid's own color changing; and the tube shows no bending, tearing, or other shape distortion.
level_4: Everything required for the 3-point level holds, and in addition no drop is blurred into a smear that hides how many drops fell or exactly when a drop touched the liquid; the liquid surface stays calm before the first acid drop and after the last ammonia drop settles (a brief bubble or small ripple exactly when a drop lands, or while CO₂ gas is escaping during the acid-dissolution step, is expected and should not count against the video); and no duplicated or missing reflection of the tube or droppers appears on the glass or tabletop.
level_5: Everything required for the 4-point level holds, and in addition every drop's fall from the dropper tip to the liquid surface is shown as one unbroken motion with no skipped frames; the liquid surface dips and settles back smoothly each time a drop lands (again, brief CO₂ bubbling during acid dissolution is expected and not a deduction); and each of the three actions (placing the powder, adding the acid, adding the ammonia) has one clear moment where it begins and one clear moment where it ends, with nothing left ambiguous by fast cuts or freeze frames.