Domain: Engineering — Chemical Engineering
Target concept: Silver plating

Video generation prompt: Set up an electroplating silver device, using a pure silver sheet as the anode and a metal test piece that has been polished and activated as the cathode. Immerse the electrodes in a 0.1 mol/L silver-ammonia complex ion electrolyte solution, with a distance of 5 cm between the two electrodes. Apply a 0.8 V direct current power supply, and control the current density at 5 mA/cm². Continuously photograph the setup for several hours.

Evaluation guide:
(i) Target concept: Electrochemical silver plating via a silver-ammonia complex electrolyte under controlled potential, with the pure silver anode acting as the dissolving silver source.
Minimum mechanism: The silver-ammonia complex [Ag(NH₃)₂]⁺ keeps free Ag⁺ concentration low and steady, which favors a smooth, adherent deposit at the cathode; the silver anode continuously dissolves (Ag → Ag⁺ + e⁻) to resupply the electrolyte, and by Faraday's law this anodic dissolution proceeds at the same rate as cathodic deposition; it is not suppressed by the complex.
(ii)Storyline: Frame 1–2: Static shot showing both electrodes placed side-by-side, fully immersed in clear liquid inside container, with power supply wires attached. Frame 3–5: Power supply activated (visible indicator lit); cathode surface begins transitioning from dull bare metal to a continuous, mirror-like silver finish, progressing uniformly across the entire immersed area. Frame 6–10: Finish stabilizes; final state shows cathode fully coated with a reflective silver layer matching the anode's appearance; the anode retains its overall metallic silver-gray look, with at most a gradual, even thinning consistent with its continuous dissolution; electrolyte stays crystal-clear, no bubbles or turbidity. Perspective: Fixed frontal view, full setup in frame, no occlusion, all key objects fully visible and in-focus.

Manual:
Experimental Procedure
1. Place pure silver sheet (anode) and polished metal test piece (cathode) vertically side-by-side in transparent container.
2. Fill container with clear electrolyte solution until both electrodes fully immersed.
3. Connect anode to positive terminal and cathode to negative terminal of DC power supply.
4. Turn on power supply showing 0.8 V output.
Observation of Experimental Phenomena
- Cathode surface gradually becomes uniformly shiny and silver-colored.
- Anode may show slight, gradual thinning consistent with continuously supplying silver to the electrolyte, but keeps its overall metallic luster without pitting or discoloration during the recording.
- Electrolyte stays transparent and bubble-free.
Summary of Experimental Principles
Silver ions from the silver-ammonia complex [Ag(NH₃)₂]⁺ migrate to the cathode and reduce to metallic silver, plating its surface. At the same time, the pure silver anode continuously oxidizes (Ag → Ag⁺ + e⁻), and the released Ag⁺ is recomplexed by free ammonia to reform [Ag(NH₃)₂]⁺; by Faraday's law this anodic dissolution proceeds at the same rate as cathodic deposition, replenishing the electrolyte's silver content over the multi-hour run. The ammonia complex moderates the free Ag⁺ concentration to favor a smooth, adherent deposit — it does not prevent anodic dissolution.

Prompt Grounding rubric:
level_1: No electroplating setup is visible: at least two of the following are missing (the silver sheet anode, the metal test-piece cathode, the electrolyte solution, the DC power supply, or immersion of the electrodes). No recognizable plating context is shown.
level_2: At least one correct object appears (e.g., the metal test piece or the silver sheet), but the setup is not shown as functional: the electrodes are not immersed, no electrolyte is visible, there is no visible power-supply connection, or the electrodes are not positioned in the same container.
level_3: All five core objects are present and spatially coherent: the pure silver sheet (anode), the polished metal test piece (cathode), a transparent liquid-filled container, a visible DC power supply with wires connected to both electrodes, and both electrodes fully immersed side by side in the same solution.
level_4: Everything in score 3 holds, and the electrodes are visibly fixed in a stable, parallel orientation with consistent spacing (not overlapping, crossing, or floating above the liquid), and the power supply shows an active status indicator (a lit LED or a labeled voltage display).
level_5: Everything in score 4 holds, and the silver anode is visibly intact and metallic gray-white, the metal test-piece cathode is visibly smooth and polished (no scratches or oxidation) before plating begins, the electrolyte is fully transparent and motionless (no bubbles, flow, or agitation), and both electrodes keep the same vertical alignment and position relative to each other throughout the video.

Scientific and Causal Correctness rubric:
level_1: No plausible plating change appears: for example the cathode changes color before the power supply is switched on, the cathode develops a color inconsistent with silver (blue, black, or red) with no explanation, or the anode shows sudden, dramatic pitting or flaking rather than the slow, even dissolution expected of a soluble silver anode.
level_2: The power supply is connected and active, but the cathode shows no surface change at all; or the cathode develops a non-metallic coating (a white haze, film, or blotchy discoloration) instead of a reflective silver layer.
level_3: The cathode's exposed surface transitions from bare metal to a continuous, uniform, reflective metallic layer over the course of the video; the anode keeps its overall metallic silver-gray appearance (a gradual, even thinning is normal and expected, since the anode is the dissolving source of silver), with no gas evolution, sudden pitting, or solution discoloration.
level_4: Everything in score 3 holds, and the new layer on the cathode matches the anode's brightness, reflectivity, and hue, with no localized defects on the cathode (no spotting, peeling, streaking, or patchiness).
level_5: Everything in score 4 holds, and the cathode's deposited layer covers only the face immersed toward the anode, not just the back or the edges; any loss of surface material on the anode is uniform and gradual across its immersed face rather than pitted or patchy, consistent with continuous anodic dissolution feeding the [Ag(NH3)2]+ electrolyte being reduced at the cathode.

Spatiotemporal Consistency rubric:
level_1: The anode, cathode, or wires vanish and reappear, or shift position with no motion shown between frames; the electrolyte level jumps up or down without cause; the lighting flips abruptly from full shadow to a bright highlight; the container or an electrode visibly bends or warps in a way solid glass and metal cannot.
level_2: One frame shows both electrodes standing upright and the next shows the cathode tilted, with no motion shown in between; the electrolyte surface flickers between still and rippled with nothing disturbing it; a wire visibly detaches from its terminal and reattaches with no hand or motion causing it.
level_3: The anode and cathode stay side by side, fully immersed in the same container, for the whole video; nothing drifts into or out of frame; the shadow the setup casts on the table keeps the same direction and softness throughout; the container walls and electrode positions look the same from frame to frame.
level_4: Everything in score 3 holds, and the camera viewpoint never pans, tilts, or zooms; the gap between the anode and cathode looks the same width throughout, neither narrowing nor widening; the electrolyte surface stays flat and still with no ripples, waves, or meniscus wobble.
level_5: Everything in score 4 holds, and motion between frames is smooth with no stutters, jump-cuts, or ghosting; the container, electrodes, wires, and power supply keep the same visible size and position relative to one another from the first frame to the last, with no gradual drift in framing or shape, confirming both the camera and the setup stay steady throughout.