Question

why do the colour and solution of copper sulphate change when we take a solution of copper sulphate in a beaker and put an iron nail in it?​

Answer 1

Answer with Explanation

In Order to Understand the reason behind this we first have to know the reactivity series which is listed below :-

$\large\begin{tabular}{c | i} Reactivity & Series\\ \cline{1-2} P & Potassium \\Na & Sodium\\Ca& Calcium\\ Mg & Magnesium\\ Al& Aluminum\\C & Carbon\\Zn & Zinc\\Fe & Iron \\ Sn&Tin \\ Cu&Copper \\Au&Gold \end{tabular}$

Now , In The above Prescribed Table you can see Iron is above then Copper which shows that Cu is Less reactive as compare to iron.

Let's back to the question , The Color of Copper Sulphate Solution (CuSO4) is change from blue to pale green when we put some iron nails in it.

This Happens becuase of Displacement reaction in which highly reactive metals ions displaces less reactive metals ions.

We Already see in the above table that iron is more reactive than copper so it displaces the copper ions and resulting into the color changement of the given solution.

Answer 2

Answer:

Procedure:

Clean two iron nails of sufficient size by rubbing them with sand paper so that their colour appears grayish.

Take sufficient quantity of copper sulphate solution in two different test tubes.

Clamp the test tubes to different stands.

Tie one nail using a thread and hang in one test tube. Tie the other end of the thread to the stand.

Keep the other nail in a Petri dish for comparison after the experiment.

Keep the two test tubes undisturbed for about 15 minutes.

Remove the iron nail immersed in the copper sulphate solution and put it in the Petridish.

Simulator Procedure (as performed through the Online Labs)

Drag any one of the iron nails tied with the thread to immerse it in one of the test tubes containing copper sulphate solution.

Wait for 15 minutes to complete the reaction.

Click on the thread to remove the iron nail from the test tube.

You can compare the iron nail removed from the test tube with the other iron nail.

You can also compare the colour of the solution after the experiment with the solution in the other test tube.

To see the inference, click on the inference icon.

You can click on the ‘Reset’ button to redo the experiment.

Note: Click on the ‘HELP’ button to see the instructions.

Observations:

There is a brown coating on the iron nail dipped in the copper sulphate solution. Whereas the iron nail placed in the Petri dish shows the grayish colour of iron.

The colour of the solution of copper sulphate in which the iron nail was dipped changes to light greenish, whereas the colour of copper sulphate solution in the other test tube does not change.

Inference:

The brown coating on the iron nail shows that copper is deposited on the iron nail by displacing iron.

The greenish colour of the solution in the test tube shows that Fe2+ ions are present in the solution.

This shows that iron is more reactive than copper, as Fe2+ ions have displaced Cu2+ ions from copper sulphate solution.

This is a single displacement reaction in which copper has been displaced from iron from copper sulphate solution.

Precautions:

Clean the iron nails by rubbing with sand paper to remove rust, dust or greasy surface.

Keep the control experiment to compare the colour of iron nails and copper sulphate solution.

Avoid touching copper sulphate solution or nail dipped in copper sulphate solution as copper sulphate is poisonous.