Reaction of Iron with copper sulphate solution in water - Lab Work

To carry out the reaction of Iron with copper sulphate solution in water and classify it as physical or chemical changes

Aim

To carry out the reaction of Iron with copper sulphate solution in water and classify it as physical or chemical changes.

Theory
Physical Change: These changes can be observed and take place without changing the composition of substances. There are no changes in chemical nature of substance. The changes which can be observed are like change in colour, boiling point, melting point, hardness, density, fluidity, rigidity etc. The interconversion of states of matter is also a physical change.

Chemical change: In this change, chemical reaction takes place and completely a new substance with different properties is formed. There are changes in chemical properties and composition of substance.
ex: 2MgO(s) + O₂(g) → 2MgO(s)
Here, the chemical composition and properties of product MgO is totally different from its reactants Mg and O.

Materials Required
Iron nails, Copper sulphate solution, Test tubes, Stand with clamp, Thread, Sand paper, Petri Dish

Procedure

Step 1: Two nails are cleaned by rubbing with sand paper so that their colour appears greyish.
Step 2: Two stands with clamps are taken and test tube is fixed in each stand.
Step 4: Sufficient amount of copper sulphate solution is poured in both test tube.
Step 4: One iron nail is tied with a thread and hanged in one test tube and other end of the thread is tied with the stand keeping in mind that the iron nail is completely immersed in the solution.
Step 5: Other iron nail is kept in a petridish for comparison after the experiment.
Step 6: Test tubes are left undisturbed for 15 minutes.
Step 7: After 15 minutes, iron nail immersed in copper sulphate solution is removed and put in petri dish.

Observation

1. There is a brown coating on the iron nail which was dipped in the copper sulphate solution, whereas the iron nail placed in petri dish shows greyish colour of iron.
2. The colour of the copper sulphate solution in which the iron nail was dipped turns light greenish, whereas the solution of copper sulphate in the other test tube does not change.

Inference
1. The brown coating on the iron nail shows that copper is deposited on the iron nail by displacing iron.
2. The greenish colour of the solution in the test tube shows that Fe²⁺ ions are present in the solution.
3.This shows that iron is more reactive than copper as Fe²⁺ ions have displaced Cu²⁺ ions from copper sulphate solution and form light greenish coloured ferrous sulphate solution.
Reaction involved: Fe(s) + CuSO₄(aq) → FeSO₄(aq) + Cu(s)
4. This is a single displacement reaction in which copper has been displaced by iron from copper sulphate solution and a new compound, ferrous sulphate, is formed. So, this reaction is a chemical change.

Precautions
1. Clean the iron nails by rubbing them with sand paper to remove rust, dust or greasy surface.
2. Keep the control experiment to compare the colour of iron nails and copper sulphate solution.
3. Avoid touching copper sulphate solution or a nail dipped in copper sulphate solution because it is poisonous.

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