please please please help me???

Question

A student carelessly allows some aluminum tongs to sit a beaker containing CuCl2 solution for a period of tim and a reaction occurs.
The original mass of tongs : 85.1 g
Final mass of tongs: 73.2 g

a) calculate the moles of atoms of aluminum reacted.
b)calculate the number of atoms of aluminum that reacted.
c) Calculate the moles of atoms of copper that are produced. (Hint: use ratio)
d) Calculate the mass of copper that is produced

Answer 1

Atomic mass of Al: 26.9815 = A
Atomic mass of Cu: 63.546 = C
C/2 - A/3 = 22.779
The mass lost? gain? from the tongs: 85.1 - 73.2 = 11.9 (g)
Mole of electron transfered: 11.9 / (C/2 - A/3) = 0.522

a) 0.522/3 = 0.174 (Mol)
corresponding to 4.70 g of Al reacted
b) 0.174 * 6.022x10^23
c) 0.522/2 = 0.261 (Mol)
d) 0.261*63.546 = 16.6 g
Notice 16.6 - 4.7 is exactly 11.9. The atomic mass of Cu is much higher. One mole of electron transfer would involve 32g of Cu deposited. On the other hand, atomic mass of Al is much lower. One mole of electron transfer would involve 9g of Al dissolved. So the original mass should be altered with the final mass of the tongs!!