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Gas calculation

發問:

An inexpansible vessel contains air at 50 degree Celsius . What percentage of air remains in the vessel if it is heated to 100 degree Celsius at constant pressure (You may take the ice point to be 273 K ) 更新: 點解用 percentage change 唔得既 thank you 更新 2: 點解 percentage change 同percentage of air remains有分別 萬分感激 thank you

最佳解答:

Apply Charles Law: V1/T1 = V2/T2 where V1 and V2 are the old and new volumes of gas respectively and T1 and T2 are the absolute temperatures of the gas respectively Hence, V1/(273 + 50) = V2/(273 + 100) V2 = (V1).(373/323) = 1.155(V1) Volume of air expelled = V2 - V1 = (1.155 - 1)(V1) = 0.155(V1) Percentage of air expelled = 0.155(V1)/(V1) x 100% = 15.5% Percentage of air remains = (100 - 15.5)% = 84.5% 2015-04-02 20:14:05 補充： sorry, a mistake in the calculation on the last 3 lines. The following is the right one: V1/(273 + 50) = V2/(273 + 100) V2 = (V1).(373/323) = 1.155(V1) %age of air remains =V1/V2 = 1/1.155= 0.866 = 86.6% 2015-04-06 01:11:14 補充： Q:點解用 percentage change 唔得既 A: The question asks for the percentage of gas remains. 2015-04-06 16:30:16 補充： In my original calculation, I have compared air at 50'C with that at 100'C. Because of the difference in density of air at these two temperature, the result is not correct. 2015-04-06 16:32:13 補充： In the revised claculation, we only look at air at 100'C. This gives the right answer.

其他解答:7638E7481407D16B