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anonymous

  • one year ago

How much heat does it take to melt 2.5 kg of lead when it is at its melting point (m.p. = 327.5ºC; ∆Hf = 2.04 * 10^4 J/kg) ? A. 6.2 × 10^1 J B. 8.2 × 10^3 J C. 5.1 × 10^4 J D. 1.7 × 10^7 J **thank you!:)

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  1. Michele_Laino
    • one year ago
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    is \Delta H the enthalpy change?

  2. anonymous
    • one year ago
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    i am not sure :/ i think so... it looks like this |dw:1432830397213:dw|

  3. anonymous
    • one year ago
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    i did not type the subscript clearly!

  4. Michele_Laino
    • one year ago
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    I think that it is the fusion enthalpy change

  5. anonymous
    • one year ago
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    ohh okay! :)

  6. Michele_Laino
    • one year ago
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    so, I think that the requested amount Q of heat is given by the subsequent computation: \[\Large Q = \Delta {H_f} \times m = ...Joules\]

  7. anonymous
    • one year ago
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    okay, so i plug in like this? 2.04 * 10^4 * 2.5 ?

  8. Michele_Laino
    • one year ago
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    yes!

  9. anonymous
    • one year ago
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    yay! so we get 51000? so the answer is choice C? 5.1 * 10^4 J ?

  10. Michele_Laino
    • one year ago
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    that's right!

  11. anonymous
    • one year ago
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    yay! Thank you:D

  12. Michele_Laino
    • one year ago
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    Thank you!!!!! :)

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