✔ 最佳答案
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.
