Calculate the Mass Fractions of Gold and Copper
A 9.40g wedding band is made up of gold and copper, and has a 4.382x10^22 atoms. Calculate the mass fractions of gold and copper in this 18carat gold alloy.
I have gotten this far:
1)
(Au) = gold = x
(Cu) = copper = y
9.40g = x + y
2) Ntotal = 4.382x10^22
4.382x10^22 = N(Au) + N(Cu)
3) Divide by Avogadro Number
4.382x10^22/6.022x10^23 = N(Au)/Na + N(Cu)/Na
7.277x10^2 mol = n(Au) + n(Cu)
4) Find Masses using mol amount
7.277 x 10^2 mol = m(Au)/M(Au) + m(Cu)/M(Cu)
7.277 x 10^2 mol = x/(196.97g/mol) + (9.40gx)/(63.55g/mol)
5) solve for x
This is where I am stuck, how do I solve for X?
