UPSC Civil Services (Mains), Chemistry optional · 2024 · Paper I
Q3(b)(i). Surface tension: ethanol or dimethyl ether
Question
Which of the following liquids has greater surface tension: ethanol or dimethyl ether? Explain the answer with reasons.
Answer in brief
Ethanol, because its molecules are held together by O–H···O hydrogen bonds, which dimethyl ether cannot form.
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Coverssurface tensionhydrogen bondingethanoldimethyl etherintermolecular forces
All parts of Question 3
- 3(a)(i) Viscosity of air at 298 K and at 0 K10 marks
- 3(a)(ii) Boyle temperature of Ar, CH₄ and C₆H₆5 marks
- 3(b)(i) Surface tension: ethanol or dimethyl ether5 marks
- 3(b)(ii) Pressure difference across a water droplet of radius 150 nm5 marks
- 3(c)(i) Change in Helmholtz energy on reversible isothermal compression10 marks
- 3(c)(ii) Why a tyre gets hot when it is pumped5 marks
- 3(c)(iii) Pressure of O₂ over NiO at 25 °C5 marks
- 3(c)(iv) Final temperature after Joule–Thomson expansion5 marks