Question

Posted by Matt W on Tuesday, January 4, 2011 at 3:17pm.


Calculate amount of energy needed to completely vaporize a 50g piece of 20 degree C silver
melting point 1064 C
L(f) = 64KJ/Kg

Boiling point 2856C
L(v) = 1645 KJ/Kg
c= 0.13KJ/Kg degrees C

I'm thinking I balance each side to equal each other but I'm not uure-I've done specific heat calcs with water-Could you please just tell me how to set it up

I think I take the (2856 - 20) * 50g *0.13 = 184.34kJ
Then I take 1064 - 20 * 50 g * 0.13 = 67.87
184.34/67.87 =17.40 kJ
Thank you

Answer 1

first of all
50 g is .050 kg

Answer 2

So if I did the corrections, then it would equal 18.434
and the second calculation would equal 6.786
.18434/.06786=.270 KJ

Correct, Better or still wrong

Answer 3

first heat it up from 20 to 1064
(1064 -20)(.13)(.05) = a

now melt it
64 (.05) = b

now heat it from 1064 to 2856
(2856-1064)(.13)(.05) = c

now boil it
1645(.05) = d

total heat = a+b+c+d

Answer 4

a= 1044 * .13 * .05 = 6.786
b= 64 * .05 = 3.2
c= 1792 * .13*.05 = 11.648
d= 1645 * .05 =82. 25

6.786 + 3.2 + 11.648 + 82.25 = 103.884

Where did you get this formula, please?