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5. One litre flask containing vapours of methyl alcohol (Mol mass 32) at a pressure of 1 atm. and 25°C wasevacuated till the final pressure was 10^-3mm. How many molecules of methyl alcohol were left in theflask? |
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Answer» Hi, Answer: 3.52 * 10¹⁶ molecules of methyl ALCOHOL were left in the FLASK. Explanation: GIVEN data: Volume of methyl alcohol in the flask = 1 liter Initial Pressure, P1 = 1 atm Final Pressure, P2 = 10^-3 mmHg = 1.315 * 10^-6 atm [∵ 1 atm = 760 mmHg] To find: No. of molecules of methyl alcohol left in the flask We know that according to STP conditions of a substance, at standard pressure of 1 atm 1 mole of GAS occupies 22.4 L of volume which CONTAINS 6.022 * 10^23 no. of molecules. Therefore, at P1 = 1 atm No. of moles of methyl alcohol = 1 / 22.4 = 0.0446 And, No.of molecules of methyl alcohol = 0.0446 * 6.022 * 10²³ = 2.68 * 10²² Now, at P2 = 1.315 * 10⁻⁶ atm No. of molecules of methyl alcohol left in th flask = 2.68 * 10²² * 1.315 * 10⁻⁶ = 3.52 * 10¹⁶ Hope it helps!!!! |
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