Brief description

Kipp’s apparatus (also called a Kipp generator) is a classic chemical device designed for the preparation and controlled delivery of small volumes of gases—such as hydrogen, carbon dioxide, or hydrogen sulfide—without needing external electrical power or mechanical pumps. It operates automatically using liquid hydrostatic pressure to stop and start the chemical reaction on demand.

Use / Function

• On-Demand Gas Generation: Producing steady streams of gases (H₂, CO₂, H₂S, acetylene) in laboratories and workshops.
• Controlled Chemical Reactions: Supplying reducing gases for metallurgy, synthesis, or gas analysis.
• Scale: Laboratory and small-scale manufacturing.

Operating principle

The apparatus consists of three vertically stacked chambers operating on hydrostatic balance:

1. Liquid Flow: Liquid acid is poured into the top globe and flows down through a central tube into the bottom reservoir, filling it and rising into the middle chamber.
2. Chemical Reaction: The middle chamber contains solid reactant pieces (such as iron filings, zinc, or marble chips). As acid touches the solid, chemical reaction begins, releasing gas.
3. Gas Accumulation & Stop: Gas exits through a stopcock valve at the top of the middle chamber. When the valve is closed, accumulated gas pressure forces the liquid acid out of the middle chamber back down into the bottom reservoir and up into the top globe.
4. Automatic Pause: Once the acid drops below the solid reactant shelf, reaction ceases automatically. Reopening the stopcock releases gas pressure, allowing acid to rise and react again.

How to create it

1. Prepare Three Glass Globes: Blow or acquire a three-chambered vertical glass apparatus with a top funnel globe, a middle reaction chamber, and a lower reservoir.
2. Insert Perforated Separation Shelf: Place a perforated glass ring or sieve plate between the lower reservoir and middle chamber to hold solid reactants while allowing acid passage.
3. Fit Gas Delivery Valve: Install a sealed glass or brass stopcock valve with ground glass joints on the top neck of the middle reaction chamber.
4. Load Solid Reactants: Place coarse solid lumps (e.g., iron sulfide or zinc granules) on the perforated shelf inside the middle chamber.
5. Pour Liquid Acid: Pour diluted acid (such as sulfuric or hydrochloric acid) into the top funnel until hydrostatic equilibrium is established.

Materials needed

• Essential materials:
  • Glass: For transparent, acid-resistant spherical chambers and central tube.
  • Sulfuric Acid or Vinegar: As the liquid acid reagent.
  • Iron or Zinc: As the solid metallic reactant for producing hydrogen gas.
  • Water: For diluting concentrated acids.
• Tools:
  • Blowtorch: For shaping glass necks and fitting stopcock valves.
  • Measuring Container: For diluting acid solutions safely.
• Possible substitutes:
  • Acid-Resistant Plastics (HDPE / PTFE): Modern chemical-resistant polymer vessels can replace fragile glass globes.

Variants and improvements

• Glass Kipp Generator: Standard historical version with ground glass joints.
• Plastic Kipp Generator: Shatterproof polymer version for field usage.
• Woulfe Bottle Assembly: Alternative series of interconnected bottles acting on the same hydrostatic principle.

Limits and risks

• Fragility: Glass constructions are highly vulnerable to thermal shock and impact breakage.
• Corrosive Acid Hazards: Handling concentrated or warm acids requires extreme care to avoid chemical burns and skin contact.
• Toxic / Explosive Gas Risks: Generated gases like hydrogen (explosive) or hydrogen sulfide (highly toxic) must be used in ventilated areas away from open flames.