Initial mass of copper Mass of copper and evaporating dish Mass of evaporating d

Question

Initial mass of copper Mass of copper and evaporating dish Mass of evaporating dish Mass of recovered copper Percent yield (show calculations) Describe the reaction Cu(s) + HNO_3(aq) rightarrow Describe the reaction Cu(NO_3)_2(aq) + NaOH (aq) What are you removing by this washing? _____ What copper und is present in the beaker? _____ Describe the reaction CuSO_4(aq) + Zn(s), or CuSO_4 (aq) Al(s) _____ What is present in solution? _____ What is the gas? _____ How do you know? _____ What are you removing by washing? _____ What or is your copper sample? _____ Is it uniform in appearance? _____ Suggest possible sources of error in this experiment.

Explanation / Answer

Ana 6 - The reaction between Cu(s) And HNO3(aq) is a redox reaction which means oxidation as well as reduction .

So the reaction is -

3 Cu + 8 HNO3 = 3 Cu(NO3)2 + 2 NO2 + 4 H2O

So the only two that change are Cu and N. Cu goes from 0 to +2 (loses 2 electrons) and N goes from +5 to +4 (gains 1 electron). But since there are two states for N, you have to balance the products.

Ans 7 - The product of thre reaction can be written as -

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

This type of reaction is a double displacement". Hence, the Copper (Cu) and Sodium (Na) switched places in the products. It's not "synthesis" because that involved two separate elements in reactants side (left) and the form one product on the right side.

Ans 8- The reaction that will occur is -

Cu(OH)2 (s) --> CuO (s) + H2O (l)

This reaction less us that heating copper hydro-oxide produces copper oxide which is a black solid .

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