Clement and Desormes Apparatus
Product Code : EL-H-10405
Quick answer: The Clement and Desormes Apparatus determines the ratio of specific heats of a gas, gamma = Cp/Cv, usually for air. A 10 litre glass bottle with a leak-proof brass cap and two stopcocks is pumped up, briefly opened to air, and the manometer readings give gamma. Lab Exports manufactures it in Delhi for colleges and universities.
Specifications
| Item | Specification |
|---|---|
| Vessel | Glass reagent bottle, 10 litre capacity |
| Cap | Brass, leak-proof, with bent tube |
| Stopcocks | Two: one for the pump connection, one for opening to air |
| Pressure measurement | Manometer on stand with scale (included) |
| Pump | Football-type hand pump (included) |
| Mercury | Not included |
If mercury is used in the manometer, fill and handle it under the laboratory's mercury safety rules.
How the Clement and Desormes experiment is done
The method compares two pressure differences. Air is pumped into the bottle until the manometer shows a small excess pressure h1 once the gas has returned to room temperature. The air stopcock is then opened for a moment: the gas expands adiabatically to atmospheric pressure and cools. After the stopcock is closed, the gas warms back to room temperature at constant volume and the pressure rises to a smaller excess h2. For small pressure changes, gamma = h1 / (h1 - h2).
- Check that the brass cap is tight, connect the pump to the first stopcock and the manometer to the bent tube.
- Pump air in, close the pump stopcock and wait several minutes until the manometer reading is steady; record h1.
- Open the second stopcock to the air and close it again as soon as the manometer levels equalise.
- Wait for the gas to regain room temperature and record the new steady reading h2.
- Repeat several times and average the value of gamma.
For dry air the expected value is close to 1.40, as for any diatomic gas. Results slightly lower than this usually come from closing the stopcock too late, which lets heat flow back in before the reading is fixed.
Key features
- 10 litre glass reagent bottle gives a large gas volume for steady readings
- Leak-proof brass cap with bent tube for the manometer connection
- Two stopcocks: one to the pump, one to release the gas to air
- Manometer mounted on a stand with scale for direct pressure reading
- Supplied with a football-type hand pump for filling air
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 Clement and Desormes apparatus at its works in Laxmi Nagar, Delhi, and supplies it to 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.
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- Constant Level Tank (EL-H-10403)
- Callendar and Barne's Apparatus (Continuous Flow) (EL-H-10402)
- Joule's Calorimeter (EL-H-10401)
- Lee's and Charlton's Apparatus (EL-H-10400)
- Searle's Thermal Conductivity Apparatus (EL-H-10399)
The full range is in the Heat section of the Physics Lab range.
Frequently asked questions
What does the Clement and Desormes apparatus determine?
The ratio of the specific heats of a gas, Cp/Cv, usually for air.
What is the capacity of the bottle?
The glass reagent bottle holds 10 litres and is closed by a leak-proof brass cap.
Is mercury included?
No. The apparatus is supplied without mercury; the manometer on stand and the hand pump are included.
What is the price of the Clement and Desormes apparatus?
Prices are not published on the website. Add the Clement and Desormes apparatus to the Enquiry Cart with the Add To Cart button on this page, or email [email protected] with the house code EL-H-10405 and the quantity, to receive a quotation.
Does Lab Exports manufacture the Clement and Desormes apparatus?
Yes. Lab Exports manufactures the Clement and Desormes apparatus at its works at 11/315, Lalita Park, Laxmi Nagar, Delhi 110092, under house code EL-H-10405.
Request a quote
Email [email protected] with the house code EL-H-10405 and the quantity, or add the Clement and Desormes apparatus to the Enquiry Cart with the Add To Cart button on this page. Tender buyers can also see the Tenders and OEM page.
