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Question:


cherrybhatnagar
Student
High School - 9th Grade

A 2500cm cube of hydrogen at S.T.P is subjected to 2.5 times increase in pressure. What volume will hydrogen now occupy?

temperature remaining constant

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Posted by cherrybhatnagar on Wednesday July 8, 2009 at 9:22 AM and tagged with chemistry, hydrogen, science, volume.

Answers:

  1. krishna-agrawala
    krishna-agrawala Teacher
    Graduate School

    eNotes Editor

    Best answer as selected by question asker.

    For any gas including hydrogen the following formula holds true.

    (P x V)/T = constant

    Where P = Pressure, V = Volume and T = Temperature of the gas.

    Therefore if given mass of a gas has Volume V1 at pressure P1 and temperature T1, and a volume of V2 at pressure P2 and Temperature T2:

    (P1 x V1)/T1 = (P2 x V2)/T2

    In the given problem it is assumed that the temperature remains unchanged, or T1 = T2. Therefore

    P1 x V1 = P2 x V2

    or

    V2 = V1 x (P1/P2)

    As P2 is 2.5 times P1, P1/p2 = 0.4

    Therefore V2 = V1 x 0.4 = 2500 x 0.4 = 1000 cm cube.

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    Posted by krishna-agrawala on Wednesday July 8, 2009 at 9:50 AM

  2. neela
    neela Teacher
    Graduate School

    eNotes Editor

    By Boyle's Law,  The product of pressure and volume of an ideal gas remains constant at a constant temperature. Or,P0V0 = P1V1, the temperature remaining constant.

    Po = Pressure at the STP, V0 =2500cm^3, volume of hydrogen at STP and P1 =2.5 times P0 =2.5P0  on the hydrogen gas at the same STP Temperature and V1 is the resulting volume of the gas and is to be found out.

    Substiting in the equation, we get.

    P0 *2500 = (2.5P0)*v1

    V1 =(2500*P0)/(2.5Po)

    = 1000cm^3

     

    NB: Reading between words: If the increase of pressure is 2.5 times, then the actual pressure =P0+increase of 2.5P0 =3.5P0. Under this interpretation, the  Volume, V1  under the pressure is 2500/3.5=714.29 cm^3.

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    Posted by neela on Wednesday July 8, 2009 at 9:50 AM

  3. gfoote3064
    gfoote3064 Teacher
    High School - 9th Grade

    eNotes Editor

    If the pressure goes up, the volume goes down, assuming temperature is constant. This is Boyle's law. So the volume goes down by a factor of 2.5. Or, you can write v(1)xp(1) = v(2)xP(2). 2500/2.5 = 1000 mls of 1000 cubic centimeters.

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    Posted by gfoote3064 on Sunday November 22, 2009 at 6:28 PM