Domain: Natural Science — Chemistry
Target concept: Reaction of Sodium Peroxide with Carbon Dioxide

Video generation prompt: Absorbent cotton is wrapped around yellowish sodium peroxide powder, and a glass tube is used to blow air (containing carbon dioxide) into the absorbent cotton.

Evaluation guide:
(i) Target concept: Exothermic reaction between sodium peroxide and CO₂ (from exhaled breath) releases enough heat and oxygen to ignite the surrounding cellulose cotton, producing localized combustion (glowing, charring, and/or open flame) at the contact site.
Minimum mechanism: Sodium peroxide must be yellowish (indicating proper hydration/purity); cotton must be dry and cellulose-based; airflow must contain CO₂ (exhaled breath); the reaction at the interface is exothermic and O₂-releasing enough that the cotton visibly ignites; this combustion (glow, charring, or open flame) is the expected, scientifically correct outcome, not an error to be avoided.
(ii)Storyline: [Frame 0–2] Static shot: yellowish sodium peroxide fully enveloped by white absorbent cotton; glass tube held adjacent, tip aligned with cotton surface. [Frame 3–6] Blowing begins: mouth/tube motion initiates; airflow direction visually implied (e.g., subtle cotton fiber deflection). [Frame 7–9] Reaction onset: localized cotton ignition (glowing ember, charring, and/or visible flame) appears *only* where airflow meets the wrapped region; the ignition spreads contiguously along the airflow path; sodium peroxide remains visually intact beneath the burning cotton. Perspective: fixed frontal view, centered on cotton–tube junction; no occlusion of reaction zone; cotton must remain visible throughout, even as it chars or burns.

Manual:
Experimental Procedure
1. Wrap absorbent cotton tightly around yellowish sodium peroxide powder.
2. Hold a glass tube adjacent to the wrapped cotton.
3. Blow air steadily through the tube into the cotton for ~3 seconds.
Observation of Experimental Phenomena
Cotton ignites locally at the site of airflow exposure while wrapped around sodium peroxide — typically producing a visible glow, charring, and/or an open flame due to the heat and oxygen released by the reaction; sodium peroxide remains granular beneath the burning cotton.
Summary of Experimental Principles
Sodium peroxide (Na₂O₂) reacts exothermically with CO₂ in exhaled air: 2Na₂O₂ + 2CO₂ → 2Na₂CO₃ + O₂; the heat released, combined with the O₂ produced, is typically sufficient to ignite the surrounding cotton fibers, producing visible combustion (glowing ember, charring, or open flame) at the reaction site — a classic demonstration that Na₂O₂ can act as a solid oxidizer capable of triggering spontaneous ignition of organic material.

Prompt Grounding rubric:
level_1: No absorbent cotton is shown, no yellowish powder is visible, no glass tube appears, or no blowing action is depicted; none of the three required elements (wrapped cotton, sodium peroxide powder, glass tube) are established together.
level_2: Only one or two of the three required elements are present (e.g., a glass tube and cotton appear, but no powder is visible inside the cotton, or vice versa), or the cotton merely rests beside the powder rather than wrapped around it, or no blowing action is shown at all.
level_3: Cotton is wrapped around yellowish powder, a glass tube is positioned near the cotton, and a blowing action is depicted (mouth or tube tip aimed at the cotton); but the tube's alignment with the cotton is ambiguous (unclear whether the tip is actually contacting or aimed squarely at the wrapped region), or the wrapping only loosely drapes over the powder rather than fully encircling it.
level_4: The cotton fully encircles the yellowish powder rather than merely draping over it, the glass tube is clearly aimed at the wrapped cotton surface, and the blowing action is unambiguous (visible mouth position, tube orientation, or airflow cue), with no missing, duplicated, or misidentified element.
level_5: All conditions for score 4 are met, and additionally: the cotton keeps its wrapped form and position relative to the tube throughout the whole sequence; no unrelated objects (gloves, labels, other chemicals) enter the frame; the camera view stays centered on the cotton–tube junction without a cut, zoom, or reframing that would break spatial continuity.

Scientific and Causal Correctness rubric:
level_1: No color or state change appears anywhere on the cotton, or the sodium peroxide is shown as white/gray/blue rather than yellowish, or a change occurs but with no visible connection to the blowing action (e.g., the cotton darkens before any airflow is shown).
level_2: The sodium peroxide is correctly yellowish, but the cotton shows no visible response at all (no darkening, glow, or flame) despite clear blowing action, or the cotton changes in a chemically implausible way (e.g., turns blue-green, or dissolves into liquid) instead of charring/igniting.
level_3: Yellowish sodium peroxide is visible beneath initially white cotton; during or shortly after blowing, the cotton at the contact point shows a visible thermal response (darkening, glowing, charring, or catching flame) consistent with an exothermic, oxygen-releasing reaction; the response is localized to where airflow meets the wrapped cotton, though its intensity or extent may be inconsistent frame to frame.
level_4: All conditions for score 3 are met, and additionally: the combustion response (darkening, glow, or flame) stays confined to the cotton region actually wrapped around and exposed to airflow, without spreading to unwrapped ends; the sodium peroxide itself keeps its granular, yellowish appearance beneath the burning cotton rather than dissolving or changing color; no phenomena inconsistent with this reaction appear (no colored smoke, no liquid pooling).
level_5: All conditions for score 4 are met, and additionally: the combustion visibly intensifies or spreads outward from the initial contact point along the airflow path as blowing continues, consistent with a self-sustaining exothermic reaction, and settles (glow fades, flame subsides, or charring stabilizes) once blowing stops rather than reversing or flickering inconsistently.

Spatiotemporal Consistency rubric:
level_1: The cotton's shape or the tube's position changes abruptly between frames with no visible motion connecting them, as if two different takes were spliced together; the sodium peroxide powder appears or disappears between frames independent of any cotton movement; the glass tube passes through the cotton in a way that ignores solid-object contact (clipping through it rather than resting against its surface); or the scene's overall lighting swings abruptly between bright and dim (or flashes on/off) between frames with no lamp, spark, or flame shown causing the change.
level_2: The cotton partially unwraps and then re-wraps itself without a visible hand or airflow causing it; the glass tube's distance from the cotton changes erratically between frames without matching the blowing motion; the cotton's brightness flickers unnaturally in a way unrelated to any ignition it may be undergoing.
level_3: The cotton, powder, and tube each keep a consistent shape, position, and layering (which object is in front of which) throughout; the blowing motion is continuous and physically plausible with no jerky starts or stops; the cotton keeps its wrapped form except for any gentle movement caused by airflow or by the reaction itself.
level_4: All conditions for score 3 are met, and additionally: the distance between the tube tip and the cotton surface stays visually consistent while blowing occurs; the cotton wrap stays snug against the powder rather than loosening or sliding; the tube never passes through the cotton's visible surface; the motion tempo of blowing matches a natural human breath rather than looking sped-up or frozen.
level_5: All conditions for score 4 are met, and additionally: the cotton's edges and fiber texture stay visually sharp and consistent as any charring or flame develops, with no visible tearing, doubling, or shimmering at its boundary; the glass tube's surface highlight stays in a consistent location; the region of cotton affected by airflow changes smoothly from frame to frame with no abrupt jump in the size or shape of the affected area.