Cu(NO3)2(aq) + 2NaOH(aq) --> Cu(OH)2(s) + 2NaNO3(aq)

Aqeous cupric nitrate is reacting with aqeous sodium hydroxide to form solid copper(II) hydroxide and aqeous sodium nitrate.

Here we are striving for accuracy by mixing the solution thoroughly until all the copper is converted. This insures that our error is as little as possible.