In: Chemistry
The following information is given for magnesium at 1atm: boiling point = 1.090E3
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The following information is given for magnesium at 1atm:
boiling point = 1090oC
Hvap(1090oC) = 5424 J/g
melting point = 649.0oC
Hfus(649.0oC) = 368.3 J/g
specific heat solid= 1.017 J/goC
specific heat liquid = 1.339 J/goC
A 27.00 g sample of liquid magnesium at 705.0oC is poured into a
mold and allowed to cool to 26.0oC. How many kJ of energy are
released in this process?
heat lost by Mg to freezing point = 1.339 JC x (705-649)x(27g)
=2024.568
heat lost by Mg due to solidification at 649 c = 368.3 J/gx 27
g=9944.1
Heat lost by solid metal 27 g x (1.017J/gC) x 649.0-26.0)C =
17106.957
Add up the total Joules lost and voila you have the answer