I have done most of the questons, just need help with this one?

200mlof silver nitrate with 1g of copper, the reactons

a. mass of copper used in the reacton: 1g
b. mass of beaker and dry silver: 114.815g
c. mass of empty beaker: 111.420g
d. mass of silver produced by the reaction: 3.395g
e. moles of solid copper used in reaction: 0.0157 moles Cu
f. moles of solid silver produced in reaction: 0.317 moles of Ag

2. convert the fractional mole coefficients from parts 1e and 1f to a simple whole number ratio by dividing each mole quantity by whichever is smaller: 0.0157 moles Cu / 0.057=1mole Cu. 0.317 moles Ag+ / 0.157 = 2 moles Ag.

3. write the equation for the reaction between copper and silver ion. Be sure to use the coefficients from #2: 2Ag+Cu=Cu+2+ 2Ag

4. Assume that magnesium would act atom for atom exactly the same as copper in this experiment. How many grams of magnesium would, have been used in the reaction if one gram of the silver were produced? The atomic mass of magnesium is 24.31g/mol: 0.0157 x24.21 = 0.381667 grams of Mg.

5. Explain the source for the blue color of the solution after the reacton: oxidation, from the Cu+2(aq) & water? But there was no water used...

Please help me with question 4 & 5?

For 4. it's good, well done :)

For 5, hmm, you forget one thing, the silver nitrate is aqueous and hence there is the presence of water molecules. Silver nitrate solution without water at all won't be a solution but a powder. :)

Water was not used, but was present all along.