Cu + 2AgNO3 --> Cu(NO3)2 + 2Ag
If we have 15 grams of copper, we should divide it by the atomic weight of copper to get the number of moles of copper:
15 g (1 mole/63.546 g) = 0.236 moles copper
From the equation above, we can see that one mole of copper produces two moles of silver, so multiply the number of moles by 2:
0.236 moles * 2 = 0.472 moles silver
Now multiply the moles of silver by the atomic weight of silver to get the number of grams of silver produced:
0.472 moles (107.87 g/mole) = 50.91 grams silver
So 50.91 grams of silver are produced.