A student investigated the reactions of copper carbonate and copper oxide with dilute hydrochloric acid. How can a sample of copper chloride crystals be made from copper carbonate and dilute hydrochloric acid?

In both reactions one of the products is copper chloride.

2 Answers
Jun 11, 2017

We can write out the stoichiometric equations for each scenario....


#CuCO_3(s) + 2HCl(aq)rarrCuCl_2(aq) + CO_2(g)uarr + H_2O(l)#


#CuO(s) + 2HCl(aq)rarrCuCl_2(aq) + H_2O(l)#

For each acid base reaction the product is the beautiful blue-coloured #[Cu(OH_2)_6]^(2+)# ion, which is commonly represented by #Cu^(2+)(aq)#, i.e. the #"aquated cupric ion......"#

Jun 11, 2017

You can do it like this:


Copper(II) carbonate neutralises the hydrochloric acid:


Put about 25 ml 1M acid into a beaker. Warm gently . Do not boil! Wear eye protection.

Remove from the heat.

Add the green copper(II) carbonate powder slowly using a spatula. Be careful as the #sf(CO_2)# is quickly evolved. Stir the mixture.

Continue adding the powder until you see traces of unreacted carbonate left at the bottom of the beaker. You have now ensured that all the acid has been used up.

You have added the copper(II) carbonate in excess.

Now separate the unreacted solid from the green solution by filtration.

You should have a clear solution that looks like this:


Pour into an evaporating dish. Heat over a water bath to make the solution more concentrated. You can test this by dipping in a glass rod and seeing if crystals form.

If they form you can cover the dish with a piece of filter paper and let the solution crystallise naturally


The steps are shown above.

You should end up with nice crystals like this: