Domain: Natural Science — Chemistry
Target concept: Pour the vinegar into the baking soda powder, and confirm that it produces a large number of dense bubbles within 5 seconds, with continuous effervescence and no odor.

Video generation prompt: Place baking soda powder into a transparent container, then slowly pour vinegar onto the powder. The pouring action is clear and continuous. The materials used are common household chemicals. The procedure focuses on adding liquid to a solid to trigger a visible reaction.

Evaluation guide:
(i) Target concept: Heterogeneous acid-base reaction producing gaseous product at room temperature.
Minimum mechanism: Solid sodium bicarbonate must be in direct physical contact with aqueous acetic acid; reaction kinetics require immediate gas nucleation at interface; CO₂ solubility in water is low, ensuring rapid bubble formation and ascent; no catalyst, heat, or secondary reagent required.
(ii)Storyline: [Frame 1–2] Static shot: empty transparent container centered. [Frame 3–4] White powder is placed into container and comes to rest. [Frame 5–6] Vinegar source (e.g., bottle) enters frame top-right; stream initiates and moves downward. [Frame 7] First liquid contact with powder: simultaneous onset of bubble nucleation at interface. [Frame 8–10] Bubbles rise continuously, densely, and exclusively from contact zone; liquid remains colorless and clear; container stays fixed; viewpoint unchanged; no extraneous motion or sensory proxies for odor.

Manual:
Experimental Procedure
1. Place a small amount of white baking soda powder into a transparent container.
2. Slowly pour vinegar liquid from a separate vessel directly onto the powder.
Observation of Experimental Phenomena
Dense, rapidly rising bubbles appear at the liquid-powder interface within seconds of contact, forming continuous effervescence with no color change, smoke, flame, or odor.
Summary of Experimental Principles
Acetic acid in vinegar reacts with sodium bicarbonate to produce carbon dioxide gas, water, and sodium acetate — the visible bubbles are CO₂ escaping the aqueous mixture.

Prompt Grounding rubric:
level_1: No transparent container visible; no baking soda powder present; no vinegar liquid visible; no pouring action depicted; no solid-liquid contact shown.
level_2: Transparent container is present and contains a white powdery substance, but the substance is not placed before pouring; vinegar is present as a liquid but is not poured; or pouring occurs without prior placement of powder; or container is opaque.
level_3: Transparent container is present; white powdery substance is placed inside it before any liquid appears; vinegar liquid is visibly poured onto the powder; pouring action is continuous and directed at the powder; all objects match common household appearance (e.g., clear cup, white powder, colorless-to-pale-amber liquid).
level_4: All conditions for score 3 are satisfied, AND the pouring action begins only after the powder is fully stationary in the container; the powder remains unmoved until liquid contact; no extraneous objects (e.g., hands holding powder container mid-air during pour) break the step sequence; viewpoint remains fixed showing full container and pour trajectory.
level_5: All conditions for score 4 are satisfied, AND the pouring motion originates from a distinct, identifiable liquid source (e.g., bottle or measuring cup with visible liquid level), moves continuously downward into the container without hesitation or reversal, and terminates only after full contact is established: no frame shows liquid suspended mid-air without downward motion toward powder, no frame shows powder dispersing before first liquid contact.

Scientific and Causal Correctness rubric:
level_1: No effervescence observed; no bubbles appear at any time; or bubbles appear without liquid-solid contact; or bubbles are static, non-growing, or non-dense; or reaction produces visible smoke, flame, color change, or odor-indicating byproduct (e.g., yellow vapor, brown residue).
level_2: Bubbles appear but only after >5 seconds from first liquid contact; or bubbles are sparse, isolated, or non-continuous; or bubbles appear only at surface without rising from powder bed; or powder visibly dissolves without gas evolution; or liquid changes color (e.g., turns blue/pink) or becomes cloudy/opaque unrelated to bubble dispersion.
level_3: Dense bubbles appear within the timeframe implied by continuous pouring (i.e., bubbles emerge during or immediately after liquid contact); bubbles originate from the interface between liquid and powder; bubbles rise continuously upward through liquid; no odor-related visual proxy (e.g., person recoiling, fumes, warning text) appears; no color change in liquid or powder.
level_4: All conditions for score 3 are satisfied, AND bubble density is visually high (bubbles occupy >30% of visible liquid volume at peak); bubble motion is upward and turbulent (not laminar or still); effervescence persists without pause for ≥2 consecutive seconds after onset; no solid residue disappears without bubble production.
level_5: All conditions for score 4 are satisfied, AND bubbles are exclusively confined to the region of liquid-powder contact and extend upward uniformly without lateral spreading beyond liquid column; no bubble collapse or film formation dominates; no frame shows liquid level dropping, powder floating, or liquid splashing out due to overreaction; motion and distribution remain physically constrained to gas evolution from heterogeneous reaction.

Spatiotemporal Consistency rubric:
level_1: Container teleports or changes position/size abruptly; powder appears/disappears without placement action; liquid appears inside container without pouring path; lighting shifts dramatically between frames; background elements flicker or morph; container deforms or fractures mid-sequence.
level_2: Container remains in place but rotates or tilts >15° without mechanical cause; powder shifts position before contact without external force; liquid stream disconnects from source (e.g., source visible in one frame, missing in next); shadow direction flips; reflection on container surface discontinuously changes intensity or location.
level_3: Container stays fixed in frame; powder remains stationary until liquid contact; liquid stream maintains visible continuity from source to target across frames; shadows, highlights, and reflections remain consistent in relative position and intensity; no object flickers, vanishes, or duplicates.
level_4: All conditions for score 3 are satisfied, AND the spatial relationship between source (e.g., bottle), stream, and target (container) remains geometrically plausible: stream does not bend unnaturally, does not pass behind occluders then reappear without occlusion logic, and maintains consistent thickness and opacity throughout its visible length.
level_5: All conditions for score 4 are satisfied, AND motion parallax is consistent: foreground objects (e.g., hand, bottle) move faster across frame than background; no inter-frame jitter, warping, or perspective contradiction (e.g., container top edge curves upward in one frame, straight in next); no temporal aliasing (e.g., frozen droplets mid-fall followed by sudden displacement).