Hofmann Voltameter
Product Code : EL-E-10975
Quick answer: The Hofmann Voltameter is a glass apparatus of three parallel tubes joined at the base, used to electrolyse water and measure the gases produced. The two side tubes, graduated 0-50 x 0.2 mL, collect hydrogen and oxygen in a 2:1 ratio by volume, which matches the formula H2O. Lab Exports manufactures it in Delhi for schools, colleges and universities.
Specifications
| Item | Detail |
|---|---|
| Construction | 3 parallel glass tubes joined by a horizontal tube |
| Graduation | Side tubes 0-50 mL x 0.2 mL |
| Filling | Central tube fitted with a funnel |
| Electrode fitting | Open lower ends of the side tubes take bungs holding the electrodes |
| Gas outlets | Jets with stopcocks on the side tubes |
| Mounting | Clamps and support base recommended, sold separately |
How the Hofmann voltameter experiment is done
When a direct current passes through water made conducting with a little dilute sulfuric acid, the water is split into its elements. Hydrogen is released at the cathode (4H+ + 4e- gives 2H2) and oxygen at the anode (2H2O gives O2 + 4H+ + 4e-), so two molecules of hydrogen form for every molecule of oxygen. The graduated side tubes make this visible: the cathode tube collects twice the volume of gas collected in the anode tube.
Because each side tube has its own stopcocked jet, the two gases can be drawn off and tested separately: hydrogen burns with a squeaky pop at a lighted splint, and oxygen relights a glowing splint.
- Mount the voltameter in clamps on a support base and fit the electrodes, in their bungs, into the lower ends of the side tubes.
- Open both stopcocks and fill the apparatus through the central funnel with dilute acid until the side tubes are full, then close the stopcocks.
- Connect the electrodes to a low-voltage DC supply and switch on.
- Read the gas volumes in the side tubes at intervals; the cathode volume is twice the anode volume.
- Draw off each gas through its jet and test it with a splint.
With the current and time recorded, the same set-up can be used with Faraday's laws to relate the charge passed to the volume of gas produced.
Key features
- Three parallel glass tubes joined at the base
- Side tubes graduated 0-50 mL in 0.2 mL divisions
- Central funnel for easy filling
- Stopcocked jets to collect and test each gas separately
- Bung fittings for electrodes at the lower ends of the side tubes
Documentation and supply
Installation instructions and a manual are supplied with the apparatus. Most Lab Exports products carry a one-year manufacturer warranty.
Lab Exports manufactures the Hofmann voltameter at its works in Laxmi Nagar, Delhi, and supplies it to schools, colleges and universities in India and 60+ countries, handling the export documents for each shipment. More about the company is on the About Lab Exports page.
Related Electrolysis products
- Electrodes Round (EL-E-10976)
- S Shape Electrodes (EL-E-10977)
- Student Gas Voltameter (EL-E-10978)
- Simple Cell, Student Kit (EL-E-10979)
- Salt Bridge (EL-E-10980)
- Fruit Clock (EL-E-10981)
The full range is in the Electrolysis section of the Chemistry Lab range.
Frequently asked questions
What does the Hofmann voltameter demonstrate?
The electrolysis of water into hydrogen and oxygen, with the side tubes showing that the volume of hydrogen is twice that of oxygen.
What is the graduation of the side tubes?
0 to 50 mL in 0.2 mL divisions.
Is a stand included with the Hofmann voltameter?
Clamps and a support base are recommended and are sold separately.
What is the price of the Hofmann voltameter?
Prices are not published on the website. Add the Hofmann voltameter to the Enquiry Cart with the Add To Cart button on this page, or email [email protected] with the house code EL-E-10975 and the quantity, to receive a quotation.
Does Lab Exports manufacture the Hofmann voltameter?
Yes. Lab Exports manufactures the Hofmann voltameter at its works at 11/315, Lalita Park, Laxmi Nagar, Delhi 110092, under house code EL-E-10975.
Request a quote
Email [email protected] with the house code EL-E-10975 and the quantity, or add the Hofmann voltameter to the Enquiry Cart with the Add To Cart button on this page. Tender buyers can also see the Tenders and OEM page.
