Domain: Natural Science — Chemistry
Target concept: Detection of zinc ions in sphalerite (dithizone colorimetric method)

Video generation prompt: Transfer the sphalerite powder into a colorimetric tube, add dilute nitric acid to dissolve it, then add 2 drops of dithizone reagent and shake.

Evaluation guide:
(i) Target concept: Visual confirmation of Zn²⁺ via dithizone chelation requires sequential dissolution then complexation; minimum mechanism: sphalerite must first be mineralogically dissolved (by HNO₃) to liberate Zn²⁺, and dithizone must contact the aqueous Zn²⁺ to form the colored complex; no direct solid-state reaction.
(ii)Storyline: [Frame 0–2] Sphalerite powder (gray-white, granular) is poured from spatula into upright colorimetric tube (clear, cylindrical, marked); [Frame 3–5] Colorless dilute nitric acid flows from dropper bottle into tube, submerging powder; undissolved solid gradually disappears over ~1.5 s; [Frame 6–7] Green dithizone reagent dispensed as two distinct spherical drops from dropper tip into solution surface; [Frame 8–10] Tube shaken horizontally with rapid oscillation → liquid vortex forms → homogeneous violet-red color emerges uniformly across solution volume; entire sequence observed from fixed frontal viewpoint with static lighting and no cutaways.

Manual:
Experimental Procedure
1. Transfer sphalerite powder into a colorimetric tube.
2. Add dilute nitric acid to dissolve the powder completely.
3. Add exactly two drops of dithizone reagent, then shake vigorously.
Observation of Experimental Phenomena
After shaking, the solution turns violet-red — indicating Zn²⁺ ions complexed with dithizone.
Summary of Experimental Principles
Zinc ions in sphalerite react with dithizone under acidic conditions to form a stable, extractable violet-red chelate complex, enabling colorimetric detection.

Prompt Grounding rubric:
level_1: No sphalerite powder, no colorimetric tube, no dilute nitric acid dropper bottle, and no dithizone dropper bottle appear anywhere; or none of the three core actions (transferring powder, adding acid, adding dithizone) is shown.
level_2: Only one or two of the four core objects (powder, tube, nitric acid bottle, dithizone bottle) are present; at most one of the three core actions occurs; the dithizone dropper is never shown dispensing anything.
level_3: All four core objects are present: sphalerite powder, colorimetric tube, dilute nitric acid bottle, and dithizone bottle; the powder is transferred into the tube, acid is added, and dithizone is dispensed, but the two dithizone drops are not shown as visibly separate, discrete drops, or the shaking step is missing entirely.
level_4: All four objects are clearly distinguishable by shape and container type; the powder is fully transferred into the tube; acid is added as a visible pour into the tube; exactly two separate dithizone drops enter the liquid surface; the tube is shaken afterward, but the shaking looks like only a slight tilt or wobble rather than clearly agitating the liquid, with no visible swirl or meniscus movement.
level_5: All four objects are present and unambiguous: gray-white granular sphalerite powder, a clear graduated colorimetric tube, colorless dilute nitric acid in a labeled dropper bottle, and green dithizone reagent in a separate dropper bottle; the powder is fully transferred into the tube before acid is added; the nitric acid enters as a continuous stream that submerges the powder; exactly two distinct dithizone drops are shown forming, detaching, and landing on the liquid surface; immediately afterward the tube is gripped and shaken with visible horizontal oscillation that produces a swirling vortex and a moving meniscus, all within one continuous shot with no cutaway.

Scientific and Causal Correctness rubric:
level_1: No color change occurs anywhere in the clip; the solution stays colorless/clear, or keeps the pre-mixing appearance, after dithizone is added and the tube is shaken, so no evidence of a Zn²⁺–dithizone complex forms.
level_2: A color appears but is scientifically wrong for this complex (e.g., blue, yellow, or black rather than violet-red); or the color appears before the sphalerite has visibly dissolved (powder still present when color appears); or the color forms only as a thin ring at the liquid surface or tube wall rather than through the bulk solution.
level_3: Violet-red color appears in the bulk solution only after the acid has visibly dissolved the sphalerite powder and after the dithizone drops have been added and the tube shaken, but the color is uneven (streaks or a two-tone solution) or fades noticeably before the clip ends.
level_4: Violet-red color develops uniformly through the whole solution after both the dissolution step and the shaking step are complete; no sphalerite powder remains visible when the color appears; no leftover green from undissolved dithizone or brown/yellow tint from the acid is visible in the final solution, but the violet-red hue looks pale or diluted rather than rich and saturated.
level_5: Violet-red color appears only after the shaking step finishes, filling the entire tube uniformly with no visible solid particles or separate colored layers; the hue is a deep, saturated violet-red consistent with the zinc–dithizone chelate, not tinted green, blue, or brown; once formed, the color holds steady in both shade and coverage for the rest of the clip.

Spatiotemporal Consistency rubric:
level_1: The colorimetric tube's position or the camera's framing jumps abruptly between frames, such as the tube being upright in one frame and tipped or relocated in the next with no connecting motion; a dithizone drop appears already resting on the liquid surface with no forming or falling motion; the sphalerite powder disappears from the tube without the acid having visibly submerged it; or the lighting abruptly brightens or darkens, or shadows jump between frames, with no visible cause in the scene.
level_2: The tube stays roughly in place, but the hand or dropper bottle vanishes mid-action and reappears in a different pose mid-pour; the acid stream or a dithizone drop skips several intermediate frames so the liquid level or drop shape jumps rather than flows continuously; the tube rotates by a large angle between two frames with no visible in-between rotation; or the tabletop/background behind the tube changes color or texture partway through the shot.
level_3: The tube stays centered in the frame at a fixed distance from the camera; the acid pour, the two dithizone drops, and the shaking motion each proceed as one continuous, uninterrupted action; the powder's disappearance visibly coincides with the acid covering it rather than vanishing on its own, though the handheld framing shows slight jitter or a brief one-to-two-frame pause during a transition.
level_4: The camera viewpoint and tube position stay fixed throughout with no jitter or freeze frames; the acid pour, the formation and detachment of each of the two dithizone drops, and the shaking oscillation are all shown as smooth, uninterrupted motions matching how a hand would actually perform them; the liquid's vortex during shaking rises and falls in step with the oscillation speed, but one drop's entry into the liquid shows a brief blur that makes the exact splash moment hard to see.
level_5: The tube's position, angle, and size stay constant relative to the camera across the entire clip; every action (powder transfer, the acid stream entering the tube, each dithizone drop forming and falling, and the shaking motion) proceeds as one uninterrupted, physically coherent sequence from start to finish, with each drop visibly narrowing, detaching, falling, and merging with the liquid before the next drop begins; the liquid's vortex and meniscus movement during shaking match the visible speed and direction of the tube's motion at every moment.