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    A gas has a density of 1.655gdm^-3 at 323k and 1.01 x 10^5 Pa.Calculate Mr

    I know that we have to use

    PV =nmr to find moles
    and then us moles =mass/Mr
    but how we will find Volume or Mass???

    We have given a density
    1.655 =mass/volume
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    (1)PV = nRT

    You know this right?

    (2)Moles = mass / mr

    Therefore if we substitute (2) into (1)

    PV = (Mass / Mr) x R x T

    but we know Density = mass / Volume right?

    Re-arrange said equation above and substitute for volume and you'll get the equation with variables you want.

    Hint:
    Spoiler:
    Show


    Something can be cancelled on both sides of your final equation

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    (Original post by Bulletzone)
    (1)PV = nRT

    You know this right?

    (2)Moles = mass / mr

    Therefore if we substitute (2) into (1)

    PV = (Mass / Mr) x R x T

    but we know Density = mass / Volume right?

    Re-arrange said equation above and substitute for volume and you'll get the equation with variables you want.

    Hint:
    Spoiler:
    Show



    Something can be cancelled on both sides of your final equation


    thanks
 
 
 
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