Copper coin experiment

First of all we got our coins in salt + vinegar solution, then you out 50ml of 2moll+ naoh into a beaker, Then you heat up the bunsen burner until nearly boiling, stir as heating then you take off heat. Then you add a spatula of zinc powder into the bunsen burner and heat lightly for 3 min with the coin in it and stir while heating up, take the coin our with the tongs then rinse the coin under water. Wave the coin in the blue flame with tongs