 #1
shreddinglicks
 212
 6
 Homework Statement:

There is an alloy:
ρ=7.64 g/〖cm〗^3
Σ_a=.205 〖cm〗^(1)
Σ_s=.956〖cm〗^(1)
It has properties of two elements:
iron
M = 55.84 g/mol
σ_a=2.56 b
σ_s=11.2 b
carbon
M = 12 g/mol
σ_a=.0035 b
σ_s=5.55 b
Find the percent composition by weight of iron and carbon in the alloy.
 Relevant Equations:

Σ=σN eq 1
N=(ρN_a)/M eq 2
I found the density of carbon and iron:
ρ_fe=7.87 g/〖cm〗^3
ρ_c=2.26 g/〖cm〗^3
Using equation 2:
atom density of iron and carbon
N_fe = 8.48e22 cm^3
N_c = 1.13e23 cm^3
Using equation 1:
macroscopic scatter and absorption cross sections of iron and carbon
Σ_a,fe = .217 cm^1
Σ_s,fe = .949 cm^1
Σ_a,c = 3.95e4 cm^1
Σ_s,c = .627 cm^1
I'm lost. I think I need to get the gram atomic weight of the alloy and do a ratio:
M_i/M_alloy
to get the weight percent. I need the number density to do that and I don't see a clear way of getting it. Or maybe my approach is completely wrong.
ρ_fe=7.87 g/〖cm〗^3
ρ_c=2.26 g/〖cm〗^3
Using equation 2:
atom density of iron and carbon
N_fe = 8.48e22 cm^3
N_c = 1.13e23 cm^3
Using equation 1:
macroscopic scatter and absorption cross sections of iron and carbon
Σ_a,fe = .217 cm^1
Σ_s,fe = .949 cm^1
Σ_a,c = 3.95e4 cm^1
Σ_s,c = .627 cm^1
I'm lost. I think I need to get the gram atomic weight of the alloy and do a ratio:
M_i/M_alloy
to get the weight percent. I need the number density to do that and I don't see a clear way of getting it. Or maybe my approach is completely wrong.