Domain: Healthcare — Pharmaceutical Chemistry
Target concept: Detection of Iron Salt Impurities in Drugs

Video generation prompt: Take a small amount of sucrose sample and place it in a transparent test tube. Add 5 mL of distilled water to dissolve, then add 1 mL of dilute hydrochloric acid and 1 drop of ammonium thiocyanate reagent. Shake uniformly and observe the resulting solution.

Evaluation guide:
(i) Target concept: Detection of iron(III) via formation of a coordination complex with thiocyanate ion under acidic conditions.
Minimum mechanism: Sucrose must be dissolved to expose trace iron salts; acid must hydrolyze iron-containing compounds to liberate Fe³⁺; SCN⁻ must be introduced after acid to avoid decomposition; complex formation requires mixing to ensure contact; red/pink color arises only from [Fe(SCN)]²⁺ and is absent in absence of Fe³⁺.
(ii)Storyline: Frame 0–1: Sucrose (white crystalline solid) placed in upright transparent test tube. Frame 2–3: Distilled water poured in → sucrose dissolves fully (no residue). Frame 4: Dilute HCl added → no visible change. Frame 5: Single droplet of ammonium thiocyanate delivered → no immediate color. Frame 6–7: Tube shaken vigorously → liquid swirls uniformly. Frame 8–9: Liquid settles → entire solution exhibits uniform, stable red or pink color. Perspective: Fixed frontal close-up, tube centered, no camera movement, full tube height visible throughout.

Manual:
Experimental Procedure
1. Place small amount of sucrose sample into transparent test tube.
2. Add 5 mL distilled water; swirl gently until sucrose dissolves completely.
3. Add 1 mL dilute hydrochloric acid.
4. Add 1 drop ammonium thiocyanate reagent.
5. Shake tube uniformly for ~2 seconds.
6. Observe final solution color.
Observation of Experimental Phenomena
Solution changes from colorless to uniform red or pink after shaking.
Summary of Experimental Principles
Iron salt impurities in sucrose are hydrolyzed by HCl to release Fe³⁺ ions, which react with SCN⁻ to form blood-red [Fe(SCN)]²⁺ complex — confirming presence of iron contamination.

Prompt Grounding rubric:
level_1: No sucrose sample is visible, or no transparent test tube is present, or none of the three reagents (distilled water, dilute hydrochloric acid, ammonium thiocyanate) is shown being added, or no shaking action occurs, or there is no clear final observation moment.
level_2: At least one correct object appears (test tube or sucrose granules), but other required items are missing (e.g., no acid container, no thiocyanate dropper); some liquid is added, but the order is scrambled (e.g., thiocyanate reagent added before the acid, or before the sucrose has dissolved); no shaking is shown.
level_3: All required items are shown: sucrose granules, a transparent test tube, a distilled-water source, a dilute-HCl container, and an ammonium-thiocyanate dropper or vial; the sucrose is placed in the tube, water is added, HCl is added, one drop of thiocyanate is added, and the tube is visibly shaken, but the liquid in the final shot looks the same as it did before the thiocyanate was added.
level_4: All five objects and all six actions (place sucrose, add water, add HCl, add one thiocyanate drop, shake, observe) appear in the correct order, and the final liquid clearly looks different from the starting liquid, but something is slightly off: the change begins while the tube is still mid-shake rather than after, or the hue looks noticeably different from one camera moment to the next with no shown cause, or the dropper tip touches the inside of the test tube while dispensing.
level_5: The sucrose granules are visibly white and dissolve completely in the water before the acid is added; the acid container and the thiocyanate dropper are visually distinct from each other and from the water source; exactly one discrete drop of thiocyanate reagent enters the tube (no stream, no multiple drops); the tube is shaken only after the thiocyanate is added, and shaking continues until the liquid stops swirling; the final liquid is uniformly colored from top to bottom of the column with no lighter or darker patches; the entire sequence plays out in one continuous shot with no cuts.

Scientific and Causal Correctness rubric:
level_1: The final liquid stays colorless throughout, or it turns a color that cannot result from an Fe3+-thiocyanate reaction (e.g., blue, green, or black).
level_2: A color appears, but its timing contradicts the reaction sequence: e.g., it appears as soon as the acid is added and before the thiocyanate drop reaches the liquid, or before the tube is shaken, or only in part of the liquid column while the rest stays colorless.
level_3: Color appears only after the thiocyanate drop is added and the tube has been shaken, and the resulting hue is red or pink, but it is patchy (a streak, ring, or cloud rather than an even color), or it appears briefly and fades back toward colorless before the clip ends, or the sucrose still shows undissolved granules when the water is added.
level_4: The red/pink color appears only once shaking is complete, stays put afterward, and fills the whole liquid column evenly, with the sucrose fully dissolved before the acid step and the acid added before the thiocyanate, but a secondary issue is visible: a yellowish tinge sits on top of the red, or the color's intensity noticeably shifts between moments with no stated cause, or the difference between the 'before thiocyanate' and 'after thiocyanate' liquid is too subtle to register as a real change.
level_5: The liquid is colorless and clear right through the HCl addition; the moment the thiocyanate drop is mixed in by shaking, the entire column turns one even, saturated red/pink with no yellow, orange, or purple cast anywhere in it, and that color holds steady for the rest of the clip; the on-screen order (sucrose dissolves, then acid goes in, then the thiocyanate drop goes in, then shaking produces the color) matches the real reaction chain in which the acid frees Fe3+ from the sucrose sample and the freed Fe3+ then binds the thiocyanate ion.

Spatiotemporal Consistency rubric:
level_1: The test tube or a reagent container vanishes and reappears, the liquid level jumps to a new height with no visible pour, the tube's rotation jumps by more than a quarter turn with no hand motion shown, or the shot cuts to a visibly different lighting setup partway through.
level_2: More than two abrupt cuts interrupt the shot; the dropper appears empty in one moment and full again the next with no visible refill; the shaking motion starts or stops instantly rather than ramping up or down; the tube's position shifts sideways by a noticeable amount with no visible hand carrying it.
level_3: The test tube, reagent containers, and liquid keep the same relative arrangement throughout (nothing floats or drifts out of place), and there is at most one small hiccup: for example, a hand briefly blocks the view during one addition, or the tube wobbles slightly while being shaken without leaving the frame or changing shape.
level_4: Pouring the water, acid, and thiocyanate all show a smooth, continuous stream or drop rather than jump-cut liquid levels; the shaking motion visibly speeds up and then slows to a stop rather than starting/stopping instantly; the liquid's surface settles gradually after shaking rather than snapping flat; the tube stays framed the same way throughout, but one brief visual hiccup (a flash, a stray flicker, or a half-second blur) appears somewhere in the clip.
level_5: The whole sequence (pouring water, adding acid, adding the thiocyanate drop, shaking, and settling) plays out as one unbroken, physically continuous motion with no cuts, flashes, or occlusions; the test tube stays in the same spot and orientation the entire time; the liquid's surface only ever moves the way pouring or swirling would actually make it move; the lighting and the shadow the tube casts look the same in the last frame as in the first.