Answer: composition in weight percent = 41.25% Cu and 58.75% Zn
Composition in Atom percent = 40.54% Cu and 59.46% Zn
Explanation:
Starting with the composition in weight percent.
Let Mcu= mass of cu and Mzn= mass of zn
%W= weight percent
%Wcu = (Mcu/(Mcu + Mzn)) × 100%
By substituting the values
%Wcu = (33/(33+47)) × 100%
%Wcu = (33/80) × 100%
%Wcu = 41.25%
%Wzn = (Mzn/(Mcu + Mzn)) × 100%
= 47/80 × 100%
%Wzn = 58.75%
Then we can proceed to composition in atom percent
Atomic mass of Cu= Ac = 63.5g/mol
For zn = Az = 65.4g/mol
Atom percent cu = {(%Wcu×Ac)/[(%Wcu×Ac)+(%Wzn×Az)]} × 100%
Substituting the values
= {2619.375/6461.625}×100%
=40.54% Cu
Atom percent zn = {(%Wzn×Az)/[(%Wcu×Ac)+(%Wzn×Az)]} × 100%
={3842.25/6461.625}×100%
=59.46% Zn
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