Domain: Engineering — Food and Bioprocess Engineering
Target concept: Purification of Puerarin (Hydrochloric Acid-Magnesium Powder Colorimetric Method)

Video generation prompt: Place 2 mL of Pueraria root extract into a test tube, add a small amount of magnesium powder, and drop in 3 drops of concentrated hydrochloric acid, then shake vigorously.

Evaluation guide:
(i) Target concept: Acid-catalyzed magnesium reduction of the puerarin flavonoid nucleus, yielding a red anthocyanidin-type (flavylium) chromophore rather than a chalcone.
Minimum mechanism: Presence of flavonoid structure (C6-C3-C6 with α,β-unsaturated carbonyl), Mg metal as electron donor, HCl as proton source and reaction medium, aqueous environment enabling proton-coupled electron transfer, and kinetic requirement of mechanical agitation to ensure reagent contact and hydrogen generation.
(ii)Storyline: Frame 1–2: Static shot of empty test tube → Frame 3–4: Extract poured in (amber-brown liquid fills ~1/3 tube) → Frame 5–6: Gray-black magnesium granules dispensed into tube (visible falling motion, settle at bottom) → Frame 7–8: Three discrete glossy HCl droplets descend and impact liquid surface (splash visible) → Frame 9–10: Tube gripped and shaken horizontally with rhythmic oscillation → During last 2 frames of shake: uniform red-pink tint emerges across entire liquid column, persisting after motion ceases. All events occur from fixed frontal viewpoint; no object leaves frame; lighting is diffuse and consistent; no occlusions.

Manual:
Experimental Procedure
1. Place 2 mL pueraria root extract into a clear test tube.
2. Add a small amount of magnesium powder.
3. Add 3 drops of concentrated hydrochloric acid.
4. Shake the test tube vigorously.
Observation of Experimental Phenomena
A red, pink, or magenta color develops in the solution only after vigorous shaking.
Summary of Experimental Principles
Puerarin (a flavonoid) is reduced by nascent hydrogen generated from Mg + HCl, forming a red anthocyanidin-type (flavylium) chromophore detectable by the hydrochloric acid-magnesium powder colorimetric method.

Prompt Grounding rubric:
level_1: None of the four required items/actions appear anywhere in the clip: no test tube, no amber-brown Pueraria extract, no gray-black magnesium powder, no HCl droplets, and no shaking motion of any kind.
level_2: Only one or two of the four items appear, out of order or with substituted materials, e.g., a test tube holds the extract but no magnesium powder or HCl is ever added, or shaking happens before any reagent is introduced, or a different powder/liquid replaces magnesium or hydrochloric acid.
level_3: The test tube, roughly 2 mL of amber-brown Pueraria extract, a small quantity of gray-black magnesium granules, and 3 discrete HCl droplets all appear in the correct order (extract poured first, magnesium powder added second, three HCl drops added third, vigorous shaking fourth), with recognizable object types and approximate quantities.
level_4: Everything required for the 3-point level holds, and the whole sequence stays within one continuous shot of the same tube on a fixed surface: the magnesium granules land inside the tube rather than on the rim or a hand, the three HCl drops visibly enter the liquid, and the shaking is clearly applied to the tube itself rather than implied off-screen.
level_5: Everything required for the 4-point level holds, and every object keeps a stable, recognizable identity across the whole clip: the extract's amber-brown tint before the color change, the matte gray-black granular texture of the magnesium powder, and the momentary glossy spherical shape of each HCl droplet at the instant of impact are all rendered without objects melting, doubling, or changing shape unnaturally.

Scientific and Causal Correctness rubric:
level_1: No red, pink, or magenta hue ever appears (the liquid stays amber-brown or colorless throughout), or the magnesium granules dissolve with no acid-base or redox signs (no gas evolution, no granule shrinkage), contradicting the expected Mg + HCl reduction of the puerarin flavonoid nucleus.
level_2: A color shift occurs but is the wrong kind for this reaction, e.g., only a darker brown or orange tint appears with no red/pink/magenta component, or a red tint appears immediately upon HCl contact before any shaking, or the magnesium granules vanish completely with no residual solid, which is inconsistent with the granules acting as the reducing agent over time.
level_3: A clear red, pink, or magenta tint appears in the liquid only after the shaking step is finished, the color is spread evenly through the liquid column rather than confined to one layer, and some undissolved magnesium granules remain visible both before and after the color appears, consistent with gradual consumption of the metal.
level_4: Everything required for the 3-point level holds, and the red/pink/magenta tint visibly deepens while shaking is still happening rather than appearing all at once, settles into a stable hue within a couple of seconds after shaking stops, and stays confined to the liquid itself, with no staining of the tube wall or of the remaining magnesium granules, and no competing bubbling or cloudiness.
level_5: Everything required for the 4-point level holds, and the resulting hue reads unambiguously as warm red-pink (not violet, orange, or blue), the intensity stays even and does not fade or streak for the remainder of the clip, and the causal chain is visible in order: magnesium contacting acid, fizzing at the granule surfaces, then the puerarin flavonoid nucleus turning into the red anthocyanidin-type (flavylium) chromophore only once shaking has mixed the reagents.

Spatiotemporal Consistency rubric:
level_1: The tube's position jumps between shots, magnesium granules appear already inside the tube with no visible entry, HCl droplets appear mid-air and disappear before touching the liquid, the liquid's volume changes abruptly with no addition shown, or the lighting shifts abruptly (brightens, darkens, or flickers) between frames with no cause shown.
level_2: The tube rotates or reorients with no supporting hand or mechanism visible, the magnesium powder falls in a way that looks like smoke or fog rather than solid granules, the three HCl drops smear into a continuous stream instead of staying distinct, or the liquid sloshes in physically impossible ways during shaking (e.g., splitting into floating blobs).
level_3: The tube stays in a fixed spot on the surface except when being shaken, the magnesium granules fall and settle with believable weight and speed, the three HCl droplets keep a spherical shape until they hit the liquid surface and produce a visible splash, and the shaking shows a coherent back-and-forth tube motion matched by sloshing of the liquid inside.
level_4: Everything required for the 3-point level holds, and the motion throughout looks physically smooth: no sudden starts or freezes mid-swing, the liquid shows a normal curved meniscus before and after each step, the magnesium fully settles before the next reagent is added, and each HCl droplet's impact produces a brief dimple and ripple rather than an instant flat surface.
level_5: Everything required for the 4-point level holds, and the order of events stays causally sound throughout (the droplets hit the liquid before any mixing begins, the magnesium settles before shaking starts, and the red color only begins to appear after the shaking motion is underway), while the camera holds one fixed frontal angle with no zoom, tilt, or drift for the entire clip.