Domain: Healthcare — Pharmaceutical Chemistry
Target concept: Purity Determination of Paracetamol (Sodium Nitroprusside Colorimetric Method)

Video generation prompt: Place the acetaminophen sample in a test tube, add an alkaline solution, and then slowly drip in the sodium nitroprusside reagent. Gently shake to ensure uniform mixing. Use standard laboratory glassware to clearly demonstrate the order of reagent addition and the controlled mixing process.

Evaluation guide:
(i) Target concept: Colorimetric detection of acetaminophen purity via formation of a stoichiometric blue complex under alkaline conditions.
Minimum mechanism: Acetaminophen must be in solid crystalline form initially; alkaline solution must fully wet and dissolve it to generate reactive phenoxide; sodium nitroprusside must be added as discrete droplets to avoid local excess; gentle shaking ensures homogeneous reaction without splashing or foaming; blue chromophore forms only upon complete molecular interaction in solution.
(ii)Storyline: [Frame 0–2] White crystalline acetaminophen rests in bottom of upright test tube → [Frame 3–4] Alkaline solution poured in, wetting solid and forming clear-to-turbid liquid layer → [Frame 5–6] Sodium nitroprusside droplet emerges from dropper tip and descends vertically into liquid → [Frame 7–8] Droplet contacts liquid surface and disperses; simultaneous onset of gentle rotational shaking → [Frame 9–10] Liquid becomes uniformly blue with no undissolved solid or phase separation; view remains fixed, frontal, and unobstructed throughout.

Manual:
Experimental Procedure
1. Place white acetaminophen powder in clean test tube.
2. Add alkaline solution to dissolve and alkalinize.
3. Slowly drip sodium nitroprusside reagent into tube.
4. Gently shake tube to mix.
Observation of Experimental Phenomena
A distinct blue color develops in the liquid phase after mixing.
Summary of Experimental Principles
Under alkaline conditions, sodium nitroprusside's reactive nitrosyl ligand forms a colored coordination complex with the phenolate form of acetaminophen, producing the characteristic blue color used in this bench-top identification test (the same general nitroprusside-complexation principle used in other classic colorimetric spot tests, such as Rothera's test for ketones). This in-vitro reaction is distinct from NAPQI (N-acetyl-p-benzoquinone imine) formation, which is a separate CYP450-enzyme-mediated oxidative metabolic pathway occurring in the liver, not in this alkaline sodium-nitroprusside test-tube reaction.

Prompt Grounding rubric:
level_1: Fewer than two of the required elements appear on screen: e.g., no test tube, no white acetaminophen powder inside it, no alkaline solution being poured in, and no sodium nitroprusside dropper visible; the powder-then-alkali-then-nitroprusside-then-shake sequence never happens at all.
level_2: The test tube and acetaminophen powder are shown, but the reagent sequence is broken: the alkaline solution is never added, or the sodium nitroprusside is poured as a stream instead of dripped, or no shaking ever occurs, or nitroprusside is added before the alkaline solution.
level_3: The test tube holding white acetaminophen powder is shown; alkaline solution is added first; sodium nitroprusside is then introduced dropwise from a dropper (not poured as a continuous stream); a shaking motion follows afterward; the required order (powder, then alkali, then nitroprusside, then shake) is all present, though the individual drops may not be clearly distinguishable from one another, or there is a noticeable pause between the last drop and the start of shaking.
level_4: All four elements (powder, alkaline addition, dropwise nitroprusside addition, and shaking) occur in the correct order within one continuous shot; individual drops of nitroprusside are visible leaving the dropper tip and landing in the liquid before the shaking begins; the test tube stays inside the frame with the dropper held above its mouth throughout.
level_5: Everything at level 4 holds, and in addition the dropper tip stays centered over the tube's mouth for every drop without drifting sideways; shaking begins almost immediately after the last drop lands, with no idle pause; and the camera never cuts away or repositions, keeping the tube, dropper, and hand in view from start to finish.

Scientific and Causal Correctness rubric:
level_1: The liquid never changes color at all; or the final liquid is green, brown, colorless, or black instead of blue; or the powder itself changes color before either the alkaline solution or the nitroprusside is added; or the sodium nitroprusside is shown already blue before it ever touches the test tube's contents.
level_2: A color change happens but is scientifically wrong: the liquid turns blue as soon as the alkaline solution alone is added, before any nitroprusside is dripped in; or it turns deep red or purple instead of blue; or a blue tint briefly appears and then fades away within the same clip; or the powder dissolves and colors on its own with no reagents ever added.
level_3: The liquid turns a clearly blue color only after all three steps have happened in order: alkaline solution added, sodium nitroprusside dripped in, then shaken; the blue color is confined to the liquid inside the tube, never appearing on the dry powder or inside the dropper itself; no color shows up during the powder-only or alkali-only stages.
level_4: Beyond level 3, the blue develops evenly through the entire liquid column rather than as a thin streak or a ring at the surface; no secondary tint (a yellow halo from unreacted nitroprusside, a brown edge, a pink fringe) appears alongside the blue; the color does not show up prematurely while the nitroprusside droplet is still falling or just touching the surface.
level_5: Beyond level 4, the blue only becomes fully visible once the shaking has stopped and the liquid has settled, not while it is still swirling; the color fills the whole liquid volume with no visibly lighter patch or leftover clear layer near the bottom; no trace of the original yellowish nitroprusside reagent color remains visible anywhere in the tube.

Spatiotemporal Consistency rubric:
level_1: The test tube's position on the table changes between one moment and the next with no hand seen moving it; the acetaminophen powder is already sitting inside the tube in an early shot with no moment showing it being placed there; the dropper is shown already mid-drip with no lead-up to it; the wrist-shake begins before the falling nitroprusside droplet has even touched the liquid surface; an abrupt, unexplained change in lighting or a shadow jump occurs mid-sequence.
level_2: The test tube's tilt or position changes abruptly between consecutive moments without any matching hand motion; the dropper tip jumps sideways while still releasing liquid; the liquid level inside the tube jumps up or down without a matching drop having landed; the light on the glass flickers, or the shadow beneath the tube suddenly shifts to a new angle mid-clip.
level_3: The test tube stays in the same spot on the surface the entire time; the dropper stays lined up above the tube's mouth; the alkaline-solution container sits beside the tube without shifting position; the shaking is one smooth, continuous wrist rotation; nothing (tube, dropper, powder, or liquid) blinks out of frame or suddenly changes size.
level_4: Beyond level 3, the tube's round cross-section and upright angle never warp or bulge; the falling nitroprusside droplet keeps a round shape all the way down instead of stretching or smearing; the liquid surface stays level once the shaking stops rather than staying tilted; the glass wall shows no sudden stretching or perspective jump between moments.
level_5: Beyond level 4, the droplet's fall from the dropper tip to the liquid surface reads as one unbroken path with no jump or freeze; the wrist-shake keeps a steady rhythm and range of motion without suddenly speeding up or stopping short; once shaking ends, the liquid surface settles back to flat gradually rather than snapping flat instantly.