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Math Help - For Chemistry, Please help

  1. #1
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    For Chemistry, Please help

    just a little rusty on the conversion side of maths at the moment, so was wondering about this question:

    'An ice cube is 2.00 in. on a side and weighs 1.2*10^2 grams.

    a) what is the density of the ice?
    b) what volume of water (d=1.00g/ml) is obtained when the ice cube melts?'

    I have attempted part a, but never got the real answer (which is 0.916g/cm^3)

    so here is what I was starting:
    d=mass/vol.

    mass = 1.20*10^2g

    converting in. to cm: 1in. = 2.54cm
    therefore 2in. * (2.54cm/1in.) = 5.08 cm.

    therefore vol.= pi(5.08)^2(5.08)
    = 411.85

    so d=mass/vol.

    1.20*10^2g/411.85=0.291


    I don't know what I have messed up, but if someone could help me understand, that would be appreciated!!
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  2. #2
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    Re: For Chemistry, Please help

    It's an ice CUBE.
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  3. #3
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    Re: For Chemistry, Please help

    so where should I 'cube' it?
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  4. #4
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    Re: For Chemistry, Please help

    A cube is a particular sort of rectangular solid, \pi does not come into the calculation of its volume.
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  5. #5
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    Re: For Chemistry, Please help

    isn't the formula for the volume of a container V=pi(r^2)h?
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  6. #6
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    Re: For Chemistry, Please help

    That's the formula for the volume of a cylinder radius r and height h, not a cube.
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  7. #7
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    Re: For Chemistry, Please help

    ooh. could you please tell me what I am meant to do in the equation instead?
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  8. #8
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    Re: For Chemistry, Please help

    The only thing that you did wrongly was the calculation of the volume of the cube.
    Suppose that you have a rectangular box, picture a shoe box say.
    If its dimensions are a cm * b cm * c cm, what is its volume ?
    For a cube, a = b = c.
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  9. #9
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    Re: For Chemistry, Please help

    so all that is, is 2in=2in=2in. how does that fit in? also, why and where do I change from in. to cm.?
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