Domain: Healthcare — Pharmaceutical Chemistry
Target concept: Ribavirin Detection

Video generation prompt: An appropriate amount of ribavirin sample was placed in a test tube, followed by the addition of an appropriate amount of sodium hydroxide solution and copper sulfate solution. The image was continuously captured with the camera aligned with the test tube.

Evaluation guide:
(i) Target concept: Under alkaline conditions, Cu²⁺ coordinates with the nitrogen atoms of ribavirin's carboxamide group and the adjacent triazole ring (a biuret-type Cu–N chelation) to form a violet-purple, poorly soluble Cu(II)-ribavirin complex, mechanistically distinct from simple Cu²⁺–vicinal-diol chemistry, which instead dissolves Cu(OH)₂ into a deep-blue solution.
Minimum mechanism: Ribavirin must be in solid crystalline form initially; NaOH must establish alkaline pH so the amide nitrogen can coordinate Cu²⁺; CuSO4 must supply Cu²⁺; chelation requires both conditions simultaneously and yields an insoluble colored complex.
(ii)Storyline: [Frame 0–1] White crystalline ribavirin occupies bottom of upright test tube. [Frame 2–3] Colorless NaOH solution is dispensed, covering ribavirin: no color change or precipitate. [Frame 4–5] Pale blue CuSO4 solution is dispensed into same mixture: immediate localized violet/purple particle nucleation at interface. [Frame 6–10] Precipitate grows downward, forming dense granular/flocculent mass in lower tube; supernatant stays clear-to-hazy; camera remains fixed, centered, and perpendicular to tube axis; no extraneous motion, lighting shift, or object intrusion.

Manual:
Experimental Procedure
1. Place a small amount of white crystalline ribavirin powder into a clean, upright test tube.
2. Add a few drops of colorless sodium hydroxide solution to cover the powder.
3. Immediately add a few drops of pale blue copper sulfate solution into the same test tube.
4. Maintain fixed camera alignment with the test tube to continuously capture the reaction.
Observation of Experimental Phenomena
A violet or purple precipitate forms selectively after copper sulfate addition; it appears granular or flocculent and settles in the lower portion of the test tube; the supernatant remains mostly clear.
Summary of Experimental Principles
Ribavirin's carboxamide nitrogen and adjacent triazole-ring nitrogen coordinate with Cu²⁺ under alkaline conditions, forming a violet-purple, poorly soluble complex — a biuret-type Cu–N chelation distinct from simple Cu²⁺–vicinal-diol chemistry, which instead dissolves Cu(OH)₂ into a deep-blue solution without requiring alkaline amide nitrogens.

Prompt Grounding rubric:
level_1: No upright test tube is shown; no white ribavirin powder is visible; neither the sodium hydroxide solution nor the copper sulfate solution appears; the camera view is not aligned with any tube, and none of the three actions (loading powder, adding NaOH, adding CuSO4) takes place.
level_2: An upright test tube is visible, but the ribavirin powder is missing or cannot be identified as a solid; only one of the two reagents (NaOH or CuSO4) is added, or a reagent is poured into the wrong vessel; the camera drifts off-axis or repeatedly loses the tube from frame.
level_3: The test tube stands upright and stationary; a visible charge of white ribavirin powder sits at its base; both the colorless sodium hydroxide solution and the pale blue copper sulfate solution are added into that same tube, one after the other or together; the camera stays aimed at the tube for the whole sequence.
level_4: The tube, ribavirin powder, and both reagent additions appear exactly as at level 3, the sodium hydroxide is added before the copper sulfate, the ribavirin is unmistakably a dry white crystalline solid before any liquid touches it, the two reagent solutions are visually distinguishable (NaOH clear and colorless, CuSO4 pale blue), and the tube stays centered in frame without being cropped or blocked.
level_5: In addition to everything at level 4, the dry ribavirin fills roughly the bottom quarter to third of the tube before any liquid is added, the sodium hydroxide is poured first and fully submerges the powder, the copper sulfate is then added directly into that same mixture without spilling over the rim, no hand, label, or extra glassware ever enters the shot, and the camera's framing and angle on the tube stay unchanged from the first frame to the last.

Scientific and Causal Correctness rubric:
level_1: The ribavirin-NaOH-CuSO4 mixture shows no color development and no solid forms at any point; it stays clear or simply retains the pale blue of unreacted copper sulfate; or the powder disappears without any precipitate ever appearing.
level_2: Some color appears (for example the mixture only ever looks pale blue, or only ever looks purple without any solid forming), but a genuine violet or purple solid never separates out; or a solid appears before the copper sulfate solution has been added, which is not possible for this reaction.
level_3: After both the sodium hydroxide and copper sulfate have been added, a violet or purple solid forms that is visibly distinguishable from the surrounding liquid (as suspended flecks or a settled layer); this solid appears only once copper sulfate joins the alkaline ribavirin solution, and no solid appears while only sodium hydroxide is present.
level_4: Beyond level 3, the violet-purple solid appears specifically at the moment copper sulfate reaches the alkaline ribavirin solution (not when ribavirin and NaOH are mixed alone, and not from copper sulfate or NaOH by themselves), the solid has a granular or fluffy clumped texture rather than a smooth gel or a fully dissolved tint, and the liquid above it stays clear to only slightly cloudy rather than uniformly colored.
level_5: Beyond level 4, the violet-purple solid becomes visible within about one to two seconds of the copper sulfate reaching the mixture and keeps thickening for the rest of the clip, no brown, green, black, or orange tint ever appears in the solid or the liquid, no bubbling, fizzing, or steam/mist appears, and the solid stays concentrated near the bottom of the tube rather than spreading evenly through the liquid.

Spatiotemporal Consistency rubric:
level_1: The test tube vanishes and reappears partway through the clip, or the ribavirin powder or reagent streams jump from one position to another without any pouring motion connecting them; the scene swings from total darkness to full brightness with no transition; motion blur is so heavy that the tube and its contents cannot be made out; or the tube itself visibly bends, splits, or melts.
level_2: The test tube's position jumps by more than a third of the frame width between shots; a reagent stream appears already in mid-fall with no visible starting point at the bottle or dropper; the violet-purple solid appears already fully formed in one frame with no frame showing it partway there; or the shadows cast on the tube change strength or direction abruptly even though the tube itself hasn't moved.
level_3: The test tube stays in the same spot and orientation throughout; the loading of the ribavirin powder and the pouring of both the sodium hydroxide and copper sulfate solutions are each shown as one continuous motion rather than a jump cut; the violet-purple solid is shown building up gradually (first as scattered specks, then as larger clumps) rather than appearing all at once; the tube itself never bends, stretches, or otherwise deforms.
level_4: Beyond level 3, each reagent pour looks physically natural (no droplets hang motionless in mid-air, no liquid flows upward or backward, no sudden unexplained speed-ups), the growing violet-purple solid stays connected to the existing mass rather than sprouting isolated patches elsewhere in the tube, the camera's framing holds steady without visible shake, and the background behind the tube does not shift or change.
level_5: Beyond level 4, the test tube's proportions and outline stay the same in every frame, with no stretching or warping of its shape; the poured reagent streams follow a single smooth path (falling straight down or in a gentle arc) at a consistent thickness rather than breaking into disconnected drops; the violet-purple solid only ever forms within the liquid and never appears smeared onto the glass above the liquid line; and moving elements such as the falling liquid or the forming solid stay crisp from one frame to the next rather than leaving a trailing double image behind them.