Domain: Natural Science — Chemistry
Target concept: Oil layer separation formed by esterification reaction

Video generation prompt: Mix 1 mL of absolute ethanol with 1 mL of glacial acetic acid, add 3 drops of concentrated sulfuric acid, and heat under a 60°C water bath for 5 minutes.

Evaluation guide:
(i) Target concept: Acid-catalyzed equilibrium esterification producing a density-driven, immiscible organic product phase.
Minimum mechanism: Reaction must proceed under mild heat (60°C) to overcome kinetic barrier; catalyst must be present *before* heating to enable measurable product formation within 5 min; product (ethyl acetate) must be sufficiently hydrophobic and less dense than aqueous phase to spontaneously separate into a stable upper layer upon formation.
(ii)Storyline: Frame opens on labeled ethanol vial → pipette draws and dispenses 1 mL into test tube → labeled acetic acid vial → pipette draws and dispenses 1 mL into *same* tube → dropper approaches tube and releases 3 discrete drops of H₂SO₄ → tube is lifted and placed into visible water bath with active thermal surface (gentle steam/ripples) → after ~2–3 sec of immersion, a sharp horizontal interface emerges and stabilizes as an upper oil layer; viewpoint remains fixed frontal close-up on tube throughout, ensuring full visibility of layer formation and no occlusion of interface.

Manual:
Experimental Procedure
1. Place 1 mL absolute ethanol into a clean test tube.
2. Add 1 mL glacial acetic acid to the same tube.
3. Add exactly 3 drops of concentrated sulfuric acid using a dropper.
4. Immerse tube in 60°C water bath for 5 min.
Observation of Experimental Phenomena
A transparent, colorless oil layer forms on top of the aqueous solution after heating; two distinct, stable, immiscible liquid phases with sharp horizontal interface.
Summary of Experimental Principles
Esterification: ethanol + acetic acid ⇌ ethyl acetate + water; catalyzed by concentrated H₂SO₄; ethyl acetate is less dense and immiscible → separates as upper oil layer.

Prompt Grounding rubric:
level_1: No ethanol, acetic acid, sulfuric acid dropper, test tube, or water bath is visible, and no mixing or heating action occurs; the scene shows something unrelated, such as plant growth or a circuit board.
level_2: At least one relevant item appears (e.g., a test tube or dropper), but the reagents are wrong or missing (no separate ethanol and acetic acid liquids, no sulfuric acid dropper, no water bath), and the action shown is unrelated, such as pouring plain water or stirring a drink.
level_3: All five required items are visible (an ethanol container, a glacial-acetic-acid container, a sulfuric-acid dropper, a test tube, and a heated water bath), with the two liquids combined and 3 drops of acid added, but the order can be scrambled or the containers mislabeled.
level_4: Every item is correctly identified: the ethanol container is labeled as absolute ethanol, the acetic-acid container is labeled as glacial acetic acid and kept separate from the ethanol, the dropper releases exactly 3 discrete drops of sulfuric acid, the tube holds both liquids before the acid is added, and the water bath is visibly heated with the tube immersed; the sequence follows ethanol → acetic acid → 3 drops of acid → immersion without any step out of order.
level_5: Everything from the 4-point level holds, and additionally: the labeling on every container stays legible throughout with no flicker or blocking; the dropper's descent is one unbroken motion releasing exactly 3 separate, non-merging drops into the same tube; the water bath shows continuous gentle steam or surface ripple for the whole heating period; the tube stays fixed and fully visible before, during, and after immersion; no item enters, exits, or duplicates on screen.

Scientific and Causal Correctness rubric:
level_1: No chemical change is visible at all (the liquid stays one uniform phase), or the tube instead shows something scientifically wrong for this reaction, such as a color change, a precipitate, or vigorous bubbling, none of which occur when ethanol and acetic acid are heated with a sulfuric-acid catalyst.
level_2: No interface ever forms; or a scientifically incorrect signal dominates instead, such as sudden cloudiness, foaming, or a color shift, none of which are produced by this esterification.
level_3: Once heating begins, a sharp, horizontal, colorless layer (the ethyl acetate product) appears above the aqueous layer inside the tube; both layers stay clear and unmixed; the boundary between them holds for at least 2 seconds without remixing.
level_4: Everything from the 3-point level holds, and additionally: no oil layer is present before immersion, and it only appears after the tube has spent some time in the 60°C bath, not immediately upon mixing or upon adding the acid; the aqueous layer stays on the bottom without becoming cloudy or swapping position; the upper layer visibly thickens over the course of heating and keeps a clean, well-defined edge.
level_5: Everything from the 4-point level holds, and additionally: the upper ethyl acetate layer shows a faint surface sheen that sets it apart from the aqueous layer under the water-bath lighting; no droplets of the upper layer re-mix into the lower one; the boundary between the two layers stays essentially flat for the remainder of the clip; no droplets of acid or reagent are seen suspended within the lower layer.

Spatiotemporal Consistency rubric:
level_1: A severe break in continuity occurs: the test tube jumps to a different position or size between shots; the liquid inside disappears or reappears without a pour or drop causing it; the room lighting swaps abruptly and without cause (e.g., daylight to a colored glow); or the clip cuts away in the middle of a drop falling, leaving its landing unresolved.
level_2: Several moderate breaks occur: more than two abrupt cuts interrupt the pouring, dropping, or heating action (e.g., a cut between a drop leaving the dropper and it landing); the tube's apparent size or rotation changes inconsistently between shots; the water level in the bath changes with no visible cause; steam appears and vanishes with no heating cue behind it.
level_3: The test tube, dropper, and water bath keep the same relative position and size across the clip; the dropper approaches from a consistent angle and height each time it is used; any steam shown rises continuously upward rather than in disconnected puffs; no object bends, stretches, or breaks apart.
level_4: Everything from the 3-point level holds, and additionally: the dropper's downward motion is one smooth, unbroken stroke; the liquid surfaces show a natural curved meniscus rather than a perfectly flat or jittery line; steam rises straight up without sudden sideways jumps; the tube does not drift or wobble while it is being immersed or heated.
level_5: Everything from the 4-point level holds, and additionally: the footage reads as one continuous take with no stutter or repeated frames; the tube and dropper in the foreground stay correctly aligned with the bath and bench in the background, with no swimming or drifting between them; the tube's base stays lined up with the rim of the bath throughout; no blur or color fringing obscures the position of the oil/water interface.