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    Wonder if some peeps could please help me with this question in my text book. It comes in two parts and the second part is the bit I really don't understand. Here's the question in full:

    A cylinder with a volume of 0.17 m3 containing 20 Kg of compressed air is stored at a temperature of 7 degrees Celcius. The pressure of the gas in the cylinder is 9.5 x 10^5 Pascals.

    The compressed air is used in a process in which the air at a temperature of 7 degrees Celcius has to be fed in at a pressure of 150 KPa and at a rate of 1000 cm3 per minute.

    1) What volume would the gas occupy at a pressure of 150 KPa at 7 degrees Celcius?

    2) What volume of air can one cylinder supply to the process?

    Now for the first part I used Boyles Law formula of P1V1 = P2V2 as the temperature stays constant at 7 degrees (280 Kelvin).
    I worked this out to be 1.08 cubic metres (when rounded) and the book says this is correct.

    But for the second part I'm totally stumped. Book says one cylinder can only supply 0.91 cubic metres to the process? Why??!! The circumstances of the process are exactly the same as in the the first question, so the answer should be the same.

    What am I missing please?

    haven't calculated... But I guess you're supposed to assume the cylinder stops supplying gas when it's pressure reaches 150 kPa.
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Updated: January 10, 2017
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