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!:)

Question

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!:)

michele_laino · Answer

is \Delta H the enthalpy change?

anonymous · Answer

i am not sure :/ i think so... it looks like this |dw:1432830397213:dw|

anonymous · Answer

i did not type the subscript clearly!

michele_laino · Answer

I think that it is the fusion enthalpy change

anonymous · Answer

ohh okay! :)

michele_laino · Answer

so, I think that the requested amount Q of heat is given by the subsequent computation:
$$\Large  Q = \Delta {H_f} \times m = ...Joules$$

anonymous · Answer

okay, so i plug in like this?

2.04 * 10^4 * 2.5 ?

michele_laino · Answer

yes!

anonymous · Answer

yay! so we get 51000? so the answer is choice C? 5.1 * 10^4 J ?

michele_laino · Answer

that's right!

anonymous · Answer

yay! Thank you:D

michele_laino · Answer

Thank you!!!!! :)