Question

Cu and Ni form a substitutional solid solution. For a 30% WT Cu/ 70% wt% Ni alloy, what fraction of the atomic sites does Ni occupy?

Answer 1

To find the atomic fraction of Ni in a 30% wt Cu/70% wt Ni alloy, convert weight percentages to atomic percentages using atomic weights, calculate moles of each element, then divide moles of Ni by total moles. Ni occupies approximately 71.6% of the atomic sites.

Step-by-step explanation:

To calculate the fraction of atomic sites that nickel (Ni) occupies in a 30 wt% copper (Cu) and 70 wt% nickel (Ni) alloy, we need to convert the weight percentages to atomic percentages using the atomic weights of Cu and Ni. The atomic weight of Cu is 63.546 amu, and for Ni, it is 58.6934 amu.

First, we find the number of moles for each element:

1. 
   
3. 
   Moles of Cu = (30 wt% Cu) / (63.546 amu) = 0.472 moles of Cu
   
4. 
   
6. 
   Moles of Ni = (70 wt% Ni) / (58.6934 amu) = 1.193 moles of Ni
   

Next, we calculate the total number of moles:

Total moles = 0.472 moles of Cu + 1.193 moles of Ni = 1.665 moles

Now, to find the atomic fraction of Ni, we divide the moles of Ni by the total moles:

Atomic fraction of Ni = (1.193 moles of Ni) / (1.665 total moles) = 0.716 or 71.6%

Thus, Ni occupies approximately 71.6% of the atomic sites in the alloy.