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    spurlingl's Avatar
    spurlingl Posts: 1, Reputation: 1
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    #1

    Apr 15, 2010, 12:54 AM
    calculating the quantity of heat required
    basically, I would like it if you could just check my work...


    1. Calculate the quantity of heat required to raise 20.1g of lead from 5.0 C to 45 C. The specific heat of lead is 0.128 J/g*C.

    Q= 20.1g x .128 J/g*C x [45-5]

    Q= 102.912 J correct?
    __________________________________________________ _______________________

    2. Calculate the quantity of heat lost when 52g of S is cooled from 85 C to 60 C. The specific heat of sulfur is 0.736 J/g*C.

    Q= 52g x .736 J/g*C x [60-80]

    Q= -956.8 J yes?
    __________________________________________________ _______________________

    3. In cooling from 75 C to 43 C, 25g of a certain substance are found to lose 669.5 J. Calculate the specific heat of the substance.

    -669.5 J = 25g x c x [43-75]
    -699.5/(25 x -32) = c
    c = .836875 J/g*C right?
    __________________________________________________ _______________________

    4. A 46g sample of iron lost 297 J of heat when it cooled down to 67 C. If the specific heat of iron is 0.460 J/g*C, calculate the initial temperature.

    -297 J = 46g x .460 J/g*C x [67-T(I)]
    -297 = 21.16 x [67-T(I)]
    -297 = 1417.72 - 21.16T(I)
    -2011.72 = -21.16T(I)
    -2011.72/-21.16 = T(I)
    T(I) = 95 C ?



    thank you so much!
    joinforfun8909's Avatar
    joinforfun8909 Posts: 12, Reputation: 3
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    #2

    Apr 15, 2010, 05:52 AM

    They look fine.

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