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
first of all
50 g is .050 kg
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
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
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?
To calculate the amount of energy needed to completely vaporize a 50g piece of 20°C silver, you need to consider the energy required for two processes: first, raising the temperature of the silver from 20°C to its melting point of 1064°C, and second, vaporizing the silver from its melting point to its boiling point of 2856°C.
1. To calculate the energy required to raise the temperature of the silver from 20°C to its melting point of 1064°C, you can use the specific heat formula: q = mcΔT, where q is the energy, m is the mass, c is the specific heat, and ΔT is the change in temperature.
The energy required for this process is:
q1 = (mass of silver) * (specific heat of silver) * (change in temperature)
= 50g * 0.13 KJ/Kg°C * (1064°C - 20°C)
= 50g * 0.13 KJ/Kg°C * 1044°C
= 676.8 KJ
2. To calculate the energy required to vaporize the silver from its melting point of 1064°C to its boiling point of 2856°C, you need to consider the heat of fusion and heat of vaporization. The heat of fusion (L(f)) is the energy required to change a substance from a solid to a liquid at its melting point, and the heat of vaporization (L(v)) is the energy required to change a substance from a liquid to a gas at its boiling point.
The energy required for this process is:
q2 = (mass of silver) * (heat of fusion) + (mass of silver) * (heat of vaporization)
= 50g * 64 KJ/Kg + 50g * 1645 KJ/Kg
= 3200 KJ + 82250 KJ
= 85450 KJ
Therefore, the total energy required to completely vaporize the 50g piece of silver is:
Total energy = q1 + q2
= 676.8 KJ + 85450 KJ
= 86126.8 KJ
So, the amount of energy needed to completely vaporize the 50g piece of 20°C silver is approximately 86126.8 KJ.