Question

Date La Than Mews TA Classifying Reactions in the Copper Cycle Report Sheet 1. Initial mass of copper 2. Mass of copper and evaporating dish 3. Mass of evaporating dish 4. Mass of uncovered copper 5 Percent yield (show calculations) 6. Describe the reaction Cu(s) + HNO (aq) + 7. Describe the reaction Cu(NO).(aq) + NaOH(aq)- - B. Describe the reaction Cu(OH),() - SUUDIO 9. What are you removing by this washing? 10. What copper compound is present in the beaker? U

Answer 1

Answer:

1. Initial mass of copper: Let us assume it to be a

2. Mass of copper and evaporating dish: Let us assume it to be b

3. Mass of evaporating dish: Let us assume it to be c

4. Mass of uncovered copper: b - c

5. Percent yield (we have shown calculation as follows): = (Mass of experimental yield/Mass of theoretical yield) x 100

For this calculation we must have molarity = X molar

volume = y L

So number of moles = Molarity x volume = X x y = Xy mole

So yield = [(Number of moles x molar mass of copper)/ Molar mass of compound]

= [(Xy) x 83,.56)/z] = 83.56 x X x y / z = 83.56 Xy/z gram

Experimental value of copper = b - c

Percent yield: = (Mass of experimental yield / Mass of theoretical yield) x 100 =(b -c / 83.56 Xy/z gram) x 100 =

D %.(Percent yield)

6. We are describing here as follows the reaction i.e. Cu (s) + HNO3 (aq)  $\rightarrow$

The reaction is shown as follows:

Cu (s) + HNO3 (aq)  $\rightarrow$ Cu(NO3)2 (aq) + NO2 (g) + H2O (l)

In this reaction copper react with concentrated nitric acid to form copper nitrate and nitrogen dioxide gas is liberated alongwith liberation of water molecule.

7. We are describing here as follows the reaction i.e. Cu(NO3)2 (aq) + NaOH (aq)  $\rightarrow$

The reaction is shown as follows:

Cu(NO3)2 (aq) + NaOH (aq)  $\rightarrow$ Cu(OH)2 (s) + NaNO3 (aq)

In this reaction copper nitrate react with sodium hydroxide to form copper hydroxide and sodium nitrate.

8. We are describing here as follows the reaction i.e. Cu(OH)2 (s)   $\rightarrow$

The reaction is shown as follows:

Cu(OH)2 (s)   $\rightarrow$ CuO (s) + H2O (l)

In this reaction copper hydroxide form cupric oxide.

9. We are removing by washing excess of reacting reagent (which is also very corrosive such as HNO3) and sodium hydroxide and sulphuric acid.

10. The copper compound present in the beaker is (black colour precipitate of) CuO.

Post Lab

Answer 1: We here write generic reaction for each of the five general classification of reactions as follows:

(1) Cu (s) + HNO3 (aq)  $\rightarrow$ Cu(NO3)2 (aq) + NO2 (g) + H2O (l)

(2) Cu(NO3)2 (aq) + NaOH (aq)  $\rightarrow$ Cu(OH)2 (s) + NaNO3 (aq)

(3) Cu(OH)2 (s)   $\rightarrow$ CuO (s) + H2O (l)

(4) CuO (s) + H2SO4 (aq)  $\rightarrow$ CuSO4 (aq) + H2O (l)

(5) CuSO4 (aq) + Mg (s)  $\rightarrow$ Cu (s) +  MgSO4 (aq)

Answer 2: Concentrated HNO3  used in the experiment is very corrosive. If it comes into contact with our skin then we should wash it off immediately with plenty of water.