Domain: Engineering — Food and Bioprocess Engineering
Target concept: Determination of Acrylamide in Food by Colorimetry

Video generation prompt: Take 2 mL of the fried potato extract into a test tube, and add one drop each of potassium bromide-potassium bromate solution and rosaniline sulfite reagent. Heat the mixture in a water bath to 40°C.

Evaluation guide:
(i) Target concept: Chromogenic detection of acrylamide via bromination-coupling reaction requiring precise reagent sequence and controlled thermal activation.
Minimum mechanism: Bromine generated in situ from potassium bromide–potassium bromate first reacts with acrylamide in the extract, consuming part of the bromine; only the bromine left over after that reaction goes on to react with the decolorized rosaniline-sulfite reagent, restoring its magenta color; heating at 40°C drives both reactions to completion within the filming window.
(ii)Storyline: [Frame 0–2] Static shot: upright test tube containing ~2 mL pale yellow-brown aqueous extract. [Frame 3–4] First droplet (colorless) dispensed from calibrated dropper into tube: visible impact and meniscus disturbance. [Frame 5–6] Second droplet (colorless) dispensed: identical impact behavior, no premature color. [Frame 7–10] Tube lowered into still, clear water bath (no bubbles, no steam); temperature cue implied by labeled 40°C device or stable thermal gradient; magenta/purple color emerges uniformly through liquid column only after immersion begins: no appearance before or outside heating context. Perspective: fixed frontal view, full tube in frame, no occlusion, consistent lighting and depth.

Manual:
Experimental Procedure
1. Place 2 mL fried potato extract in a clean test tube.
2. Add one drop of potassium bromide-potassium bromate solution.
3. Add one drop of rosaniline sulfite reagent.
4. Immerse tube in water bath at 40°C.
Observation of Experimental Phenomena
After heating, the mixture develops a distinct magenta/purple color.
Summary of Experimental Principles
Bromine generated in situ from the potassium bromide–potassium bromate solution reacts with (adds across the double bond of) acrylamide in the extract, consuming part of the bromine. Heating to 40°C drives this reaction to completion within the test period. The bromine left over after reacting with acrylamide then reacts with the rosaniline-sulfite reagent, restoring its magenta color — so the color seen is produced by residual bromine reacting with the dye, not by acrylamide itself joining the colored product.

Prompt Grounding rubric:
level_1: No test tube is visible; no fried-potato extract is in it; no potassium bromide–potassium bromate droplet appears; no rosaniline-sulfite droplet appears; no water bath or 40°C heating cue is shown; the two reagents are not added one after another.
level_2: A test tube holds some liquid, but it does not read as a pale yellow-brown potato extract; only one of the two reagent droplets appears, not both; there is no water bath or heating cue; the order of adding the two reagents cannot be told apart.
level_3: The test tube holds a light yellow-brown liquid consistent with fried-potato extract; two separate droplets go into the tube one after the other; a water-bath setting is implied (tube sitting in a warm-water bath or next to a labeled 40°C device); no droplet lands outside the tube.
level_4: Everything in the 3-point description holds, and in addition: the roughly 2 mL of extract, one colorless (or faintly yellow) drop of potassium bromide–potassium bromate solution, and one colorless drop of rosaniline-sulfite reagent are each clearly identifiable; the tube sits upright in a heated water bath with no boiling or steam; the two droplets are added as separate events, not pre-mixed before entering the tube.
level_5: Everything in the 4-point description holds, and in addition: exactly two droplets enter the tube, one right after the other, with no third droplet; nothing else touches the liquid between the first and second droplet; the water bath looks calm and non-boiling throughout, with no vigorous bubbling or sudden temperature-overshoot cues.

Scientific and Causal Correctness rubric:
level_1: No color change appears anywhere in the clip; no heating is shown; the reagents are added to the wrong medium (solid food, open air, or a colored solvent instead of the extract); the mixture ends up a color unrelated to this test (blue, green, or black) or stays colorless throughout.
level_2: Heating happens but the liquid never gains color, or color appears without any heating shown, or color appears before both droplets have been added; or a purple/magenta hue appears instantly with no heating interval shown at all.
level_3: Color only appears after both the potassium bromide–potassium bromate droplet and the rosaniline-sulfite droplet have gone in and heating has begun; the liquid ends up a visible magenta/purple, distinct from the extract's original color and from the colorless reagents; no contradictory event (a precipitate forming, the liquid separating into layers, or gas bubbling out) appears.
level_4: Everything in the 3-point description holds, and in addition: the extract starts pale yellow-brown, not clear or dark brown; both reagent droplets look colorless right before they are added; the magenta/purple color builds gradually once heating starts rather than flashing on all at once; nothing odd like glowing, shimmering, or over-saturated color appears.
level_5: Everything in the 4-point description holds, and in addition: the magenta/purple color is even throughout the liquid column, with no streaking, layering, or color only at the surface or rim; the hue reads as the rosaniline-sulfite reaction product regenerated by residual bromine: a magenta/pink-purple, not violet-blue or plain red-pink; the color does not fade or shift once it appears; the sequence on screen matches: extract alone (no color) → first droplet in (still no color) → second droplet in (still no color) → heating begins → magenta/purple appears.

Spatiotemporal Consistency rubric:
level_1: The test tube abruptly vanishes from frame and then reappears, or its liquid level jumps with no visible cause; a droplet appears already inside the tube with no fall shown, or vanishes mid-air; the water bath appears before either reagent has been added; the shot cuts between unrelated scenes; the lighting jumps between noticeably different levels from one frame to the next.
level_2: The tube shifts by more than about a third of its height to a different spot in the frame between shots; a droplet falls but misses the tube opening; the water bath only becomes visible after the color has already changed; the liquid surface moves in a way that does not match any droplet fall or heating action; the shadow cast by the tube swings to a different side with no light-source change to explain it.
level_3: The tube stays in view and upright, with no vanishing, splitting, or impossible bending; each droplet fall is at most a brief stutter, not a freeze; the liquid meniscus stays continuous through both additions; the tube does not jump position; the shadow it casts stays on the same side at roughly the same strength throughout.
level_4: Everything in the 3-point description holds, and in addition: each droplet's fall is smooth and clearly ends inside the tube; the tube stays fully visible and still through the whole clip; the water-bath line around the tube stays at the same height relative to the tube; no flicker, warping, or sudden perspective shift appears during the heating segment.
level_5: Everything in the 4-point description holds, and in addition: each droplet falls in a gravity-consistent straight line rather than floating or drifting sideways; the liquid surface visibly dips and settles back after each droplet lands; the water-bath surface stays calm and reflective the whole time; there are no dropped frames, no motion blur hiding a droplet's landing, and the tube's position relative to the camera never drifts.