A 0.325 g sample of copper was weighed out by a student to start this experiment.1. How many moles of Cu2+ ions should be produced when the nitric acid was added to the copper metal?2.When the sodium hydroxide was added to the solution, how many moles of Cu(OH)2 should have formed?3. The directions require you to add 1.00 g of zinc. If you assume a 100 % yield of copper, how many grams of zinc were added in excess?4. If magnesium metal were used instead of zinc metal, what is the minimum mass, in grams, of magnesium metal that should be used to ensure that all of the copper ions in the solution is converted back to copper metal?PLEASE HELP I'm so lost, thank you!!
0.325 g of copper = 5.11 * 10^-3 moles 1 mole of copper can make 1 mole of copper ions so you can make 5.11 * 10^-3 moles Look at the formula, Cu(OH)2. 1 mole of Cu(OH)2 contains 1 mole of Cu so you make the same number of moles of Cu(OH)2 as you have of copper. Since you have Cu+2 and Zn makes ions with a +2 charge, moles of copper = moles of zinc. If you need 5.11 * 10^-3 moles of zinc, you need 5.11 * 10^-3 * 65.38 g/mole = 0.334 g zinc With Mg, Mg also makes Mg+2 so moles of copper = moles of magnesium. If you need 5.11 * 10^-3 moles of zinc, you need 5.11 * 10^-3 * 24.305 g/mole = 0.1241 g Mg
