Audience note: This guide is written for chemistry teachers, physics teachers covering electricity and electrolysis, school lab coordinators, procurement officers, distributors, importers and university laboratory teams.
A Hofmann voltameter is a laboratory electrolysis apparatus that demonstrates how an electric current decomposes water into hydrogen and oxygen gases. In a teaching lab, the apparatus holds acidified or salt-conductive water in connected graduated glass limbs, uses electrodes connected to a DC power supply, and collects gases separately so students can observe the approximate 2:1 hydrogen-to-oxygen volume relationship. For Jlab India procurement, the confirmed internal product reference is Hoffman Voltameter With Electrodes, supported by the chemistry-lab equipment category and stand accessory where required.
How does a Hofmann voltameter demonstrate electrolysis?
A Hofmann voltameter demonstrates electrolysis by passing DC current through conductive water so water molecules decompose into hydrogen at the cathode and oxygen at the anode. The gases collect in separate graduated limbs, allowing students to compare volumes and verify the stoichiometric 2:1 hydrogen-to-oxygen relationship. For school and college use, buyers should specify the glass unit, electrodes, stand, DC power supply requirement, electrolyte guidance, packing and safety documentation. The confirmed Jlab India product pages are the Hoffman Voltameter With Electrodes, the Hoffman Voltameter Stand and the simpler Voltameter comparison option.
What is a Hofmann voltameter?
A Hofmann voltameter is a glass electrolysis apparatus used to decompose water into hydrogen and oxygen under direct current. The apparatus has connected limbs that collect gases above the electrodes, usually with graduated markings so students can compare gas volumes and verify that hydrogen forms at roughly twice the volume of oxygen.
For the confirmed Jlab India product page, the Hoffman Voltameter With Electrodes is listed for demonstrating decomposition of water, determining chemical composition by electrolysis and evaluating the electrochemical equivalent of hydrogen. The same page states that the apparatus requires a 12 V power supply and is supplied with carbon and platinum electrodes.
Table: Core working principles demonstrated by a Hofmann voltameter.
| Concept | What students observe | Teaching point |
| Electrolysis | Gas bubbles form at two electrodes when DC is applied. | Electrical energy drives a non-spontaneous chemical change. |
| Cathode reaction | Hydrogen gas collects at the cathode side. | Reduction occurs at the cathode. |
| Anode reaction | Oxygen gas collects at the anode side. | Oxidation occurs at the anode. |
| Gas volume ratio | Hydrogen volume is approximately twice oxygen volume. | Water contains hydrogen and oxygen in a 2:1 atom ratio. |
| Electrolyte role | Conductive solution allows current to pass through water. | Pure water conducts poorly; an electrolyte supports conduction. |
Core equipment and products for the experiment
A complete Hofmann voltameter demonstration needs the glass voltameter, electrodes, a safe vertical stand, a DC power source, a suitable electrolyte and teacher-controlled gas testing. A missing stand or unsuitable power supply can make the experiment unsafe or inconclusive.
Table: Core products and accessories for a complete electrolysis demonstration.
| Priority | Equipment / product | Confirmed or RFQ-dependent details |
| Essential | Hoffman Voltameter With Electrodes | Product code JLI-CLE-10574; glass limbs approx. 50 ml capacity, graduated 2-50 ml; stopcocks; supplied with 2 carbon and 2 platinum electrodes; requires 12 V power supply. |
| Required | Hoffman Voltameter Stand | Product code JLI-CLE-10636; supplied with 600 mm rod; metal stand with support clamp for safe vertical mounting. |
| Required | 12 V DC power supply | The product page states 12 V power supply is required; current limit and output protection should be confirmed in RFQ. |
| Required | Electrolyte and water | Product page mentions water and sodium/potassium sulphate or sulphuric acid; institution must follow its lab safety protocol. |
| Recommended | Gas testing materials | Matches or splints may be used only by the teacher under local school safety rules. |
| Alternative / comparison | Voltameter | Product code JLI-CLE-10665; mounted on base with terminals and two 10 ml graduated test tubes; useful as a simpler comparison apparatus. |
Specs to check before buying a Hofmann voltameter
Before buying a Hofmann voltameter, the buyer should check glass capacity, graduation range, electrode material, stopcock function, stand compatibility, voltage requirement, packing and documentation. These specifications determine whether the apparatus will work reliably in classroom demonstrations and tenders.
Table: Hofmann voltameter specifications to confirm before procurement.
| Specification | What to request in RFQ | Why it matters |
| Product code | JLI-CLE-10574 or latest equivalent code | Avoids substitution with a simpler voltameter. |
| Limb capacity | Approx. 50 ml per limb; verify current production drawing | Provides enough gas volume for visible comparison. |
| Graduation range | 2-50 ml markings; verify readability and tolerance | Allows students to compare the 2:1 gas ratio. |
| Electrodes | Confirm supplied electrode materials and quantity: 2 carbon + 2 platinum per product page | Electrode choice affects demonstration, durability and replacement cost. |
| Power requirement | 12 V DC power supply required; request current-limited output details | Supports safe classroom operation. |
| Stand and clamp | Ask whether stand is included or order JLI-CLE-10636 separately | Vertical mounting prevents tipping and uneven collection. |
| Stopcocks | Ask for leak check and smooth operation evidence | Leaky stopcocks compromise gas collection. |
| Packing | Ask for foam / partitioned export packing and fragile marking | Protects glass limbs and stopcocks in transit. |
| Documentation | Catalogue, datasheet, manual, safety note and packing list | Needed for institutional procurement and lab handover. |
Matching the equipment to institution level
Table: How Hofmann voltameter procurement changes by teaching level.
| Institution level | Recommended use | Procurement decision |
| Class 6-8 | Teacher-only demonstration of gas formation; no student handling of chemicals or flame tests. | Prefer demonstration kit only if teacher supervision and safety protocol exist. |
| Class 9-10 | Demonstrate electrolysis, conductivity and gas collection as a structured practical. | Buy complete apparatus with stand and manual. |
| Class 11-12 | Use for electrochemistry, oxidation-reduction and quantitative gas ratio observations. | Specify graduated limbs, electrodes, and DC supply compatibility. |
| College / university | Use for introductory electrochemical equivalent and Faraday-law demonstrations. | Request stronger documentation and spares. |
| Teacher training / TVET | Use as a practical setup for safe science demonstration technique. | Include SOP, inspection checklist and replacement electrode plan. |
Safety requirements for classroom electrolysis
A Hofmann voltameter should be used only under trained supervision because the experiment combines glassware, electricity, electrolyte solution and gases. Hydrogen is flammable, oxygen supports combustion, and electrolyte handling requires appropriate PPE and institutional chemical safety procedures.
Table: Safety controls for Hofmann voltameter use in school and college laboratories.
| Risk area | Required control | Procurement / lab note |
| Glass breakage | Use a stable stand and inspect limbs, funnel, stopcocks and joints before use. | Order or specify the Hoffman Voltameter Stand if not supplied. |
| Electrical supply | Use a DC supply matching the apparatus requirement; avoid exposed or loose terminals. | Ask for 12 V DC compatibility and current-limiting guidance. |
| Hydrogen gas | Keep away from open flames except controlled teacher demonstration. | Do not allow student-led gas testing. |
| Oxygen gas | Avoid oil/grease contamination and uncontrolled ignition tests. | Use small-scale teacher demonstration. |
| Electrolyte solution | Use only institution-approved electrolyte concentration and PPE. | Product page mentions sodium/potassium sulphate or sulphuric acid; verify school SOP. |
| Stopcock release | Release gases slowly and away from face. | Include operating SOP in lab handover. |
Budget and RFQ notes
Price for a Hofmann voltameter is RFQ-dependent because final cost depends on glass configuration, electrode material, stand inclusion, spares, packing, documentation and freight. The buying team should request a line-item quotation rather than a generic “electrolysis apparatus” price.
Table: RFQ structure for Hofmann voltameter procurement.
| RFQ line item | Specify this detail | Reason |
| Main apparatus | Hoffman Voltameter With Electrodes, code JLI-CLE-10574 or latest equivalent | Controls product identity. |
| Stand | Hoffman Voltameter Stand, code JLI-CLE-10636, if not bundled | Prevents incomplete delivery. |
| Power supply | 12 V DC requirement and compatible power source specification | Needed for safe operation. |
| Electrode spares | Replacement carbon and platinum electrode availability | Reduces downtime. |
| Packing | Export / domestic glass-safe packing with carton marking | Prevents transit breakage. |
| Documentation | Manual, safety note, datasheet, certificate copies if claimed | Supports tender and school handover. |
| Commercial terms | GST, freight, lead time, warranty terms and replacement policy | Must be confirmed in quotation, not assumed. |
Original proof asset: Pre-dispatch and acceptance checklist
This checklist is designed as a non-commodity procurement asset for schools and tenders. It helps verify that the Hofmann voltameter delivered to a lab is complete, safe, and demonstrably capable of showing electrolysis of water before classroom use.
Table: School acceptance checklist for Hofmann voltameter delivery and first-use validation.
| Step | Acceptance criterion | Evidence to record |
| 1. Product identity | Main item labelled as Hoffman Voltameter With Electrodes or approved equivalent. | Catalogue code / invoice line / packing label. |
| 2. Glass inspection | No crack, chip, clouding or deformation in limbs, reservoir, bulb or funnel. | Visual inspection photo. |
| 3. Graduation check | Graduations visible across stated 2-50 ml range or as quoted. | Close-up photo of markings. |
| 4. Stopcock operation | Both stopcocks open/close smoothly without leakage under water test. | Leak test observation. |
| 5. Electrode set | Carbon and platinum electrodes supplied as quoted. | Accessory count sheet. |
| 6. Stand compatibility | Glass unit mounts vertically on stand/clamp without tilt. | Mounted setup photo. |
| 7. Power compatibility | 12 V DC requirement stated in manual or datasheet; terminals fit leads. | Datasheet/manual check. |
| 8. Bubble formation | Gas bubbles appear at both electrodes when teacher tests with approved solution. | Teacher demonstration note. |
| 9. Gas separation | Gases collect separately in the two limbs. | Observation log. |
| 10. Approx. gas ratio | Hydrogen side trends toward about twice oxygen volume during controlled demonstration. | Graduation reading record. |
| 11. Packing completeness | Fragile glass packing, electrodes, stand if ordered, and manual included. | Packing list signed off. |
| 12. Safety handover | PPE, electrolyte SOP and gas-testing rules communicated to lab in charge. | Handover checklist. |
Vendor evaluation matrix
Table: Weighted evaluation method for Hofmann voltameter supplier comparison.
| Evaluation criterion | Suggested weight | How to score |
| Confirmed product identity and specs | 25% | Full score only when product code, capacity, graduation range, electrodes and power requirement are stated. |
| Safety and documentation | 20% | Score for SOP, datasheet, operating notes and chemical/electrical safety guidance. |
| Packing and transit protection | 15% | Score for glass-safe packing, carton marking and replacement policy. |
| Accessory completeness | 15% | Score for stand, clamp, electrodes, leads and power-supply compatibility. |
| Tender support | 15% | Score for GST, IEC, certificate copies if claimed, catalogue and compliance sheet. |
| After-sales / spares | 10% | Score for electrode spares, stopcock support and replacement handling. |
Common mistakes and pitfalls
Mistake 1: Buying a simple voltameter when a Hofmann voltameter is required
A simple voltameter may demonstrate electrolysis, but it may not provide the same separated graduated limbs used for gas-ratio observation. Always verify the product code and configuration.
Mistake 2: Forgetting the stand and clamp
A Hofmann voltameter must be held vertically. If the main glass apparatus is ordered without a stand, the practical may become unsafe or impossible to set up correctly.
Mistake 3: Ignoring electrode material
Electrode material affects cost, durability and demonstration quality. The Jlab India product page states that the Hofmann voltameter is supplied with carbon and platinum electrodes; buyers should confirm the current supplied set.
Mistake 4: Using the wrong electrolyte or concentration
Do not improvise electrolyte selection in a school lab. The electrolyte should follow institutional safety protocols and current curriculum/lab manual guidance.
Mistake 5: Treating gas testing as a student activity
Hydrogen and oxygen tests should remain teacher-controlled because of flammability and combustion-support risks.
Related Guides and Internal Links
- Chemistry Lab Equipment hub – commercial category authority page for this article.
- Hoffman Voltameter With Electrodes – primary product page for the electrolysis apparatus.
- Hoffman Voltameter Stand – required support accessory for vertical setup.
- Voltameter – simpler comparison product for electrolysis demonstrations.
- Lab-Tenders page – procurement and institutional tender context.
- Contact Jlab India – quotation and RFQ submission page.
Frequently Asked Questions
Which Hofmann voltameter is best for school electrolysis demonstrations?
A school should choose a Hofmann voltameter with clearly graduated gas-collection limbs, suitable electrodes, a stable stand and a compatible DC power supply. The confirmed Jlab India reference is the Hoffman Voltameter With Electrodes, and the stand should be confirmed or ordered separately. The RFQ should ask for product code, limb capacity, graduation range, electrode set, packing and manual.
How does a Hofmann voltameter show the electrolysis of water?
A Hofmann voltameter shows water electrolysis by collecting hydrogen and oxygen gases separately as DC current passes through a conductive water solution. Hydrogen forms at the cathode and oxygen forms at the anode. The visible gas volumes demonstrate that hydrogen is produced at about twice the volume of oxygen.
Is a Hofmann voltameter safe for school laboratories?
A Hofmann voltameter is suitable for school laboratories only under trained teacher supervision and with proper safety controls. The setup uses glassware, electricity, electrolyte and gases, so PPE, stable mounting, current-limited DC supply and teacher-controlled gas testing are essential. Students should not handle gas ignition tests independently.
How much does a Hofmann voltameter cost for a chemistry lab?
The cost of a Hofmann voltameter is RFQ-dependent and should not be published without a current quotation. Price depends on the glass unit, electrode material, stand inclusion, packing, documentation, freight and spares. Buyers should request a line-item quote that separates the main apparatus, stand, power supply and replacement electrodes.
How do I maintain a Hofmann voltameter after use?
A Hofmann voltameter should be rinsed after use, drained carefully, dried without forcing stopcocks, and stored upright or in protective packing. Electrodes should be inspected for corrosion or damage, and stopcocks should be checked for smooth movement before the next demonstration. Broken, cracked or leaking glassware should not be used.
What is the difference between a Hofmann voltameter and a simple voltameter?
A Hofmann voltameter is designed to collect gases separately in graduated limbs, making it better for observing the hydrogen-to-oxygen gas ratio. A simpler voltameter can demonstrate electrolysis but may not provide the same visibility or measurement structure. Buyers should match the apparatus to the experiment outcome required in the syllabus or tender.
Key Takeaways
1. A Hofmann voltameter demonstrates electrolysis by using DC current to split conductive water into hydrogen and oxygen gases.
2. The main classroom observation is the approximate 2:1 hydrogen-to-oxygen gas-volume relationship, which supports the composition of water.
3. The confirmed Jlab India product page for Hoffman Voltameter With Electrodes lists product code JLI-CLE-10574 and states that a 12 V power supply is required.
4. A stable stand and clamp are required because the glass unit must remain vertical during gas collection.
5. Procurement should specify the glass unit, electrodes, stand, DC power supply compatibility, packing, spares and documentation.
6. Prices, warranty terms, certification status and curriculum mapping should be verified from current quotation, certificate copies and official curriculum documents before tender use.
About Jlab India
Jlab India is an educational and laboratory equipment manufacturer with works address at 947, HSIIDC Industrial Estate, Saha 133104, Ambala, Haryana, India. The company website states that Jlab India has operated since 1986 and supplies educational science kits, chemistry laboratory equipment, physics laboratory equipment, biology laboratory equipment and laboratory glassware for schools, colleges, universities and laboratories.
The Jlab India About page includes certification and accreditation statements, but certificate copies should be verified before using those claims in tender submissions or compliance pages. For this article, the commercial authority page is the Chemistry Lab Equipment category, supported by the Hoffman Voltameter With Electrodes product page and the Lab-Tenders page.