# Calculating the percent composition of weight of an alloy

• Engineering
• shreddinglicks
In summary, the conversation discusses the density and atom density of carbon and iron, as well as the macroscopic scatter and absorption cross sections of these elements. The speaker also mentions trying to calculate the weight percent of an alloy, but is unsure of how to do so. They also ask for clarification on the meanings of the variables a, s, and b.
shreddinglicks
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 = 3.95e-4 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.

σ_a=2.56 b
σ_s=11.2 b

I am a layman on metal. Could you tell me what a, s, and b are ?

## 1. What is the percent composition of weight of an alloy?

The percent composition of weight of an alloy refers to the percentage of each element present in the alloy by weight. This is calculated by dividing the weight of each element by the total weight of the alloy and multiplying by 100.

## 2. How do you calculate the percent composition of weight of an alloy?

To calculate the percent composition of weight of an alloy, you will need to know the weight of each element present in the alloy and the total weight of the alloy. Then, divide the weight of each element by the total weight of the alloy and multiply by 100 to get the percentage.

## 3. Why is it important to calculate the percent composition of weight of an alloy?

Calculating the percent composition of weight of an alloy is important because it helps determine the properties and characteristics of the alloy. It also allows for accurate and precise control of the alloy's composition, which is crucial in industries such as manufacturing and metallurgy.

## 4. Can the percent composition of weight of an alloy change?

Yes, the percent composition of weight of an alloy can change. This can happen when new elements are added or removed from the alloy, or when the weight of the existing elements changes due to factors such as oxidation or corrosion.

## 5. Are there any limitations to calculating the percent composition of weight of an alloy?

One limitation of calculating the percent composition of weight of an alloy is that it does not account for the arrangement of atoms within the alloy, which can also affect its properties. Additionally, it may not accurately reflect the actual composition of the alloy if there are impurities or inconsistencies in the sample being analyzed.

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