Domain: Engineering — Chemical Engineering
Target concept: Mercury is prepared by the thermal decomposition of mercury oxide.

Video generation prompt: Take an appropriate amount of red mercury oxide powder and place it into a heat-resistant test tube. Fix the test tube at a slight downward angle on an iron stand. Heat the bottom of the test tube evenly with the outer flame of an alcohol lamp, maintaining a stable heating intensity for several minutes.

Evaluation guide:
(i) Target concept: Thermal decomposition of solid mercury oxide into elemental mercury (liquid metal) and oxygen gas under controlled heating.
Minimum mechanism: Mercury oxide must be thermally unstable above ~500°C; decomposition yields discrete liquid mercury phase (dense, reflective, coalescing droplets) and gaseous oxygen (buoyant and invisible, inferable only via faint heat-shimmer streamlines rising from the tube mouth, not through bubbling, since no liquid medium is present); reaction requires sustained energy input and produces irreversible, visually distinct phase and color changes.
(ii)Storyline: Frame 1–2: Red powder settled in upright test tube. Frame 3–4: Tube tilted downward and clamped. Frame 5–6: Alcohol lamp ignited; outer flame approaches tube bottom. Frame 7–8: Flame stably contacts bottom; powder begins fading; first mercury droplets appear near heated zone. Frame 9–10: Droplets grow/coalesce; black residue visible; oxygen streamlines rise vertically from reaction site. All events occur from fixed frontal/side viewpoint; no cuts or perspective shifts; lighting originates from lamp position and casts consistent shadows; mercury appearance strictly follows heating onset and intensifies with duration.

Manual:
Experimental Procedure
1. Place red mercury oxide powder into a heat-resistant test tube.
2. Fix the test tube at a slight downward angle on an iron stand.
3. Heat the bottom of the test tube evenly with the outer flame of an alcohol lamp.
4. Maintain stable heating until decomposition occurs.
Observation of Experimental Phenomena
- Red powder gradually fades; silvery liquid mercury droplets form on tube walls; black residue remains; colorless oxygen gas evolves, visible only as a faint heat-shimmer rising from the tube mouth (no bubbling, since the gas forms directly from a dry solid rather than a liquid).
Summary of Experimental Principles
Mercury is prepared by thermal decomposition of mercury oxide: 2HgO → 2Hg + O₂.

Prompt Grounding rubric:
level_1: None of the setup elements appear: no red mercury oxide powder, no heat-resistant test tube, no iron stand, no alcohol lamp, and no heating action of any kind.
level_2: At least one object appears (the test tube or the alcohol lamp, for instance), but there's no red powder visible inside it; the tube isn't shown clamped to any stand; the heating is either absent or clearly misapplied (flame held in open air, or aimed at the wrong object); the setup steps appear out of order or incomplete.
level_3: Red powder sits inside a heat-resistant test tube; the tube is clamped to an iron stand; an alcohol lamp with a visible outer flame sits near the tube's bottom, touching or nearly touching it, but the tube's downward tilt isn't clearly visible, or the flame isn't held steadily in place (it flickers on and off, or drifts to a different spot on the tube).
level_4: All four setup elements are correctly shown: red powder, a heat-resistant test tube, an iron stand with a clamp, and an alcohol lamp with a visible wick and outer flame; the tube is clamped at a clearly downward-tilted angle; the flame stays continuously and steadily against the tube's bottom for the whole heating period; nothing extra clutters the frame.
level_5: Everything from level 4 holds, and in addition: the downward tilt of the tube stays clearly visible from the fixed camera angle for the whole clip, with no camera move that hides it; the flame stays in the same spot relative to the tube's bottom in every frame; the powder never appears outside the tube, the flame never touches the tube's side wall instead of its bottom, and the flame is present continuously with no frame where it vanishes and comes back.

Scientific and Causal Correctness rubric:
level_1: No sign of decomposition appears: the red powder's color never changes, no silvery mercury droplets show up, and there's no visible sign of gas being released (no shimmer, no glow, nothing); the tube's contents just sit there unchanged, which isn't scientifically valid for this reaction.
level_2: The powder is shown, but it doesn't change state at all; or a liquid that looks like water rather than metal appears; or a gas effect shows up before any heating starts; or the mercury appears as a vapor cloud instead of liquid droplets; or the color change is wrong (say, black turning yellow instead of red fading toward gray/black).
level_3: The red powder visibly changes as it's heated, fading toward orange/yellow or turning into a grayish residue; small silvery liquid droplets appear on the tube's inner wall or bottom; there's no visible sign of gas escaping yet (no shimmer or streamline effect), but the droplets and residue appearing only after heating begins is enough to show partial decomposition.
level_4: Everything from level 3 holds, and in addition a faint heat-shimmer or streamline effect rises from the heated powder zone, showing the escaping oxygen gas (no bubbling, since there's no liquid medium here); the mercury droplets look distinctly silvery, metallic, and rounded, and start merging into bigger ones; the leftover residue is gray or black rather than red; nothing contradicts the reaction (no melting of the tube itself, no smoke, no charring).
level_5: Everything from level 4 holds, and in addition the mercury droplets only start appearing after the heating has been going for a while (not in the very first heated frame), and they grow in number and size steadily rather than all at once; the heat-shimmer above the reaction zone rises straight up without swirling sideways in a way that looks like more than gentle thermal convection; the leftover residue's color and grainy texture look like what's expected from decomposed mercury oxide; nothing about the droplets looks wrong for liquid mercury (no rainbow sheen, no see-through droplets, no residue dissolving away).

Spatiotemporal Consistency rubric:
level_1: Objects jump to new positions or appearances between frames with no motion connecting them; the clamped test tube suddenly appears at a different angle with no transition; the flame appears or disappears instantly with no fade; the overall lighting flips abruptly from bright to dark within a single frame; the tube cracks or bends unnaturally; the camera viewpoint switches with no cut or transition to explain it.
level_2: The test tube rotates or slides with no physical cause; the flame jumps sideways or up/down between frames instead of staying put; mercury droplets blink into existence fully formed rather than growing gradually; the gray/black residue appears all at once in the first heated frame instead of building up; the lighting flickers erratically; the shadow the flame or tube casts suddenly points a different way than before; the camera shakes hard or zooms with no reason.
level_3: A small, temporary glitch shows up: a hand briefly blocks the view of the tube then moves away; the flame's position wiggles slightly (less than about 10% of the tube's height) for a couple of frames; the scene dims briefly for one frame without losing clarity of the objects; the residue appears in one sudden step rather than fading in gradually, but stays consistent afterward.
level_4: The test tube stays clamped at the same downward angle the whole time; the flame stays right next to the tube's bottom, with no positional jump greater than about 5% of the tube's length; the mercury droplets grow smoothly in size and number; the residue builds up gradually rather than suddenly expanding; the lighting keeps the same angle, brightness, and softness throughout; there's no visible tearing, ghosting, or warping in any frame.
level_5: Everything from level 4 holds, and in addition the clamp holding the tube never appears to shift position across the whole clip; the flame stays visibly anchored to the same spot on the tube's bottom in every frame; the mercury droplets merge naturally into larger ones without ever splitting apart; the residue only spreads along the heated part of the tube, never creeping onto the cooler upper walls; the shadow edges stay sharp and steady, never softening or hardening oddly; nothing about the droplets' motion looks inconsistent with normal gravity-driven flow.