Question

MAY SOMEONE PLEASE ASSIST ME... I DO NOT UNDERSTAND THIS... IT'S A 'SELECT AN ANSWER Qs'.... (there's multiple parts to this) I'll post the questions and afterwards below are the answers to 'SELECT FROM' (To make it easier i'll just label the Questions "A, B, C, D " THANK YOU IN-ADVANCE!!

Match the correct answers.

Question:

A) In the Copper Cycle, why did the addition of Zn (s) cause Cu2+ ions to form Cu (s)?

B) In the Copper Cycle experiment, we added aqueous HCl to the reaction mixture to remove the Zn(s).  Why was it necessary to use HCl rather than another acid, such as HNO₃?

C) What does the acetone do in the wash of the copper cycle?

D) Why couldn't you use 3M H₂SO₄ for concentrated HNO₃ in part I?

[CHOICES TO SELECT FROM]

-Any strong acid should do

-Single displacement reaction and COPPER IS MORE active than Zinc

-Solid copper and nitric acid react to form a toxic nitrogen dioxide gas

-single dsplacement reaction and ZINC is MORE active than Copper

-Acetone decreases the insolubility of copper and therefore used to keep the copper a solid

-Solid Copper DOES NOT directly react with sulfuric acid, some form of oxidant is needed.

-It rinses water away leaving the solid copper with less water on it

Answer 1

A) In copper cycle, why did the addition of Zn (s) cause Cu2+ ions to form Cu (s)? - single displacement reaction and ZINC is MORE active than Copper

zinc is more reactive than copper because zinc able to loose its outer electron more readily than copper. This is because the copper metal is able to delocalize its outer electron more readily than zinc so the metallic bond of copper is stronger than zinc. Now, for breaking the stronger bond in Cu require more energy. Zinc on the other hand requires less energy to break its metallic bond and hence can react better than Cu and hence, Zinc is more active than copper.

B) In the Copper Cycle experiment, we added aqueous HCl to the reaction mixture to remove the Zn(s).  Why was it necessary to use HCl rather than another acid, such as HNO₃? - Solid copper and nitric acid react to form a toxic nitrogen dioxide gas

Copper doesn't react with HCl as copper is not active enough to displace either H⁺ or Cl^-. This can be all predicted from the electrochemical series

CuCu2⁺+2e⁻

2H⁺+2e⁻H₂

the reduction potential of the H⁺ is 0 V. The reduction potential of the copper is -0.34 V. This means that the copper is holding onto it's electrons more tightly than the H⁺ is pulling electrons to it, thus no reaction will take place.

Now, nitric acid is a very strong oxidizing agent and hence it will react with copper to oxidize it to Cu²⁺

4 HNO₃(l) + Cu(s) Cu(NO₃)₂(aq) + 2 NO₂(g) + 2 H₂O(l)

As copper can readily dissolve in nitric acid and yields NO₂, it is not advisable to use nitric acid ( as we need to precipitate out Cu) but HCl does not react with solid metal and hence it can be used.

C) What does the acetone do in the wash of the copper cycle? - It rinses water away leaving the solid copper with less water on it

Acetone is basically a volatile organic reagent which is used in laboratories for cleaning glass wares and to drying out glass wares having very little amount of water droplets in it. In the carbon cycle, acetone is used to wash the precipitate to dry it partially. As acetone is water miscible, it can be used in conjecture with water and as it is volatile as well it can easily evaporate and hence drying the precipitate

D) Why couldn't you use 3M H₂SO₄ for concentrated HNO₃ in part I? - Solid Copper DOES NOT directly react with sulfuric acid, some form of oxidant is needed

Par I in the copper cycle is basically for dissolving the Copper solid metal present. HNO₃ can readily oxidize Cu metal and hence can dissolve it as it is a very good oxidizing agent.

4 HNO₃(l) + Cu(s) Cu(NO₃)₂(aq) + 2 NO₂(g) + 2 H₂O(l)

But copper does not react with sulphuric acid as its reduction potential is very high. When present along with an oxidant, it can oxidize Cu metal and hence can dissolve the metal. But concentrated sulphuric acid when used instead of 3M H₂SO₄, copper metal can dissolve because concentrated sulphuric acid is a very good oxidizing agent.