Chemical Reactions

Burning of Magnesium in Air

Materials Required:

Lab Procedure: 

SI No. Experiment Observation Inference
Take a piece of magnesium ribbon and rub it with  sand paper to remove dirt from its surface. It looks silvery white. Colour of magnesium metal is silvery white.
2 Hold the magnesium ribbon with the help of a pair of tongs, light the magnesium and collect the ash of burnt ribbon in a china dish. It burns brilliantly and a white ash is left behind. Magnesium burns in air to form Magnesium oxide (MgO).
Take a moist red litmus paper and bring it in contact with the white ash of MgO. Red litmus paper turns blue. MgO is basic in nature.

Simulator Procedure:

You can select the reactions from the drop down list of the ‘Select Reaction’.

  • Turn on the burner by clicking on the knob of the burner.
  • Click and drag the tongs towards the burner to burn the magnesium ribbon.
  • Click on the tongs to drop the ash into the china dish.
  • You can see the inference by clicking on the inference icon.
  • Click on the spatula to put some ash (MgO) into the moist red litmus paper.
  • You can see the inference by clicking on the inference icon.
  • You can click the ‘Reset’ button to redo the experiment.

Inferences:

  • Magnesium is a silvery white metal that burns in air and utilizes atmospheric oxygen from air to form magnesium oxide.
  • Magnesium oxide changes the colour of red litmus paper to blue. This reaction shows that magnesium oxide is basic in nature.
  • The formation of magnesium oxide is a direct combination reaction of two elements: magnesium and oxygen. Magnesium oxide is entirely different from the reactants magnesium and oxygen. So, this reaction is a chemical change.

Precautions:

  1. The surface of magnesium ribbon should be properly cleaned with sand paper.
  2. The white ash of magnesium oxide should not be touched.
  3. Magnesium ribbon should be held by a pair of tongs while burning it.
  4. It is better to use sun glasses to protect eyes from dazzling light of burning magnesium ribbon.

Reaction of Iron Nails with Copper Sulphate Solution in Water

Materials Required:

Lab Procedure:

  • Clean two iron nails of sufficient size by rubbing with sand paper so that their colour appears greyish.
  • Take sufficient quantity of copper sulphate solution in two test tubes and fix one test tube in each stand.
  • Tie one iron nail with a thread and hang it in one test tube so that it is completely immersed in copper sulphate solution. Tie the other end of the thread with the stand.
  • Keep the other nail in a petri dish for comparison after the experiment.
  • Keep the two test tubes undisturbed for about 15 min.
  • After 15 min. remove the iron nail immersed in copper sulphate solution and put it in the petri dish.

Simulator Procedure:

You can select the reactions from the drop down list of the ‘Select Reaction’.

  1. Click on the iron nail tied with a thread to immerse it in one of the test tubes containing copper sulphate solution.
  2. Once its done, wait till the timer shows 15 minutes.
  3. You can see the inference by clicking on the inference icon.
  4.  Click on the thread to remove iron nail from the test tube.
  5. You can view the zoom part of the test tubes or iron nails by clicking on them.
  6. You can click the ‘Reset’ button to redo the experiment.

Observations:

  • 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.
  • 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.

Inferences:

  • 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 and form light greenish coloured ferrous sulphate solution.


 

  • 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. As copper sulphate is poisonous.
     

Heating of Copper Sulphate.

Materials Required:

Lab Procedure:

  • Take a small amount of copper sulphate crystals in a dry boiling tube.
  • Hold the boiling tube with a test tube holder.
  • Heat the boiling tube over the flame of a burner first gently and then strongly.
  • Observe the colour of copper sulphate crystals after heating for some time.
  • Note the water droplets along the sides of the boiling tube.
  • Remove the boiling tube from the flame and cool.
  • Add 2-3 drops of water on the sample of copper sulphate obtained after heating.

Simulator Procedure:

You can select the reactions from the drop down list of the ‘Select Reaction’.

  1. Click on the holder to heat the boiling tube containing hydrated copper sulphate crystals.
  2. Turn on the burner by clicking on the knob of the burner.
  3. The burner turns off automatically when blue coloured copper Sulpahte crystals changes its colour to white.
  4. You can see the inference by clicking on the inference icon.
  5. Click on the dropper to add water into the boiling tube containing anhydrous copper sulphate.
  6. You can see the inference by clicking on the inference icon.
  7. You can click the ‘Reset’ button to redo the experiment. 

Observations:

  • On heating, the colour of copper sulphate crystals changes from blue to white.
  • There are water droplets on the walls of the boiling tube.
  • On adding 2-3 drops of water white copper sulphate turns blue.

Inferences:

  • Copper sulphate crystals contain water of crystallisation (CuSO4.5H2O).
  • On heating, hydrated copper sulphate loses its water molecule and forms white coloured anhydrous copper sulphate. 
  • On adding water anhydrous copper sulphate changes to hydrated copper sulphate.
  • It is a reversible chemical change.

Precautions:

  1. Keep the mouth of the test tube away from your face and also from other classmates.
  2. Always use test tube holder while heating the test tube.
  3. Take a small quantity of copper sulphate crystals.

Reaction of Zinc with Dilute Sulphuric Acid

Materials Required:

Lab Procedure:

  • Take a small quantity of dil. H2SO4 in a conical flask.
  • Add a small quantity of zinc granules  to it.
  • Bring a wet blue and red litmus paper near the mouth of the conical flask one by one.
  • Cork the flask with a one bored cork and insert a jet tube through the hole in the cork.
  • Bring a burning candle near the mouth of the fine jet tube.
  • Pour a small amount of the solution from the conical flask into a test tube.
  • Add few drops of sodium hydroxide solution into it. A white gelatinous precipitate is formed.
  • Add excess of NaOH into the gelatinous precipitate.
  • The precipitate is soluble in excess of NaOH.
  • Take a small amount of the solution in another test tube and pass H2S gas through it using Kipp's apparatus.
  • A white precipitate is formed.

Simulator Procedure:

You can select the reactions from the drop down list of the ‘Select Reaction’.

  • You can select the tests from drop down list of ‘Select identification test’.
    • Litmus test
      • Zinc granules are added into the test tube containing dil. H2SO4 using a spatula.
      • Click & drag the litmus papers one by one over the mouth of the test tube to show it on the gas coming out of the test tube.
      • You can see the inference by clicking on the inference icon.
      • You can click the ‘Reset’ button to redo the test.
    • Hydrogen pop test
      • Click on the spatula to add zinc granules into the test tube containing dil. H2SO4.
      • The test tube is corked by a single bored cork and a fine jet tube is inserted through the cork into the test tube.
      • Click & drag the burning candle towards the mouth of the fine jet tube.
      • You can see the inference by clicking on the inference icon.
      • You can click the ‘Reset’ button to redo the test.
    • ZnSO4 with NaOH
      • Zinc granules are added into the test tube containing dil. H2SO4 using a spatula.
      • You can see the inference by clicking on the inference icon.
      • Click on the dropper to add NaOH into the test tube containing zinc sulphate solution.
      • You can see the inference by clicking on the inference icon.
      • Again click on the dropper to add excess of NaOH into the test tube.
      • You can see the inference by clicking on the inference icon.
      • You can click the ‘Reset’ button to redo the test.
    • ZnSO4 with H2S
      • Zinc granules are added into the test tube containing dil. H2SO4 using a spatula.
      • Click on the knob of Kipps apparatus to pass H2S gas through the solution in the test tube.
      • You can see the inference by clicking on the inference icon.
      • You can click the ‘Reset’ button to redo the test.

Observations:

  • After adding zinc granules to dil. H2SO4 evolution of gas bubbles occurs.
  • The gas coming out does not change the colour of blue and red litmus papers.
  • On bringing the flame, the gas coming out of the jet tube burns instantaneously with a small explosion and produce a pop sound and the flame dips out.
  • On adding NaOH to the small amount of solution taken from the conical flask, white gelatinous precipitate is formed which is soluble in excess of NaOH.
  • On passing hydrogen sulphide gas through the solution taken in the test tube a white precipitate is formed.

Inferences:

  • Zinc reacts with dil.H2SO4 to form zinc sulphate and evolve hydrogen gas.

                                                                                   

  • The test with red and blue litmus papers shows that hydrogen gas is neither acidic nor basic in nature.
  • NaOH reacts with ZnSO4 to form a white gelatinous precipitate of zinc hydroxide (Zn(OH)2) which is soluble in excess of NaOH.


                                                  

  • ZnSO4 reacts with H2S to form a white precipitate of zinc sulphide (ZnS).

  • Zinc metal is more reactive than hydrogen.
  • This is a single displacement reaction of a non-metal by a metal. 
  • ZnSO4 is entirely different in chemical composition and chemical properties than Zn and H2SO4. So it is a chemical change

Precautions:

  1. Use the chemicals judiciously.
  2. Do not inhale gases evolved directly.
  3. Hydrogen gas instantaneously burns with mild explosion. Therefore, a fine jet tube should be used to see the burning of hydrogen.
  4. Handle acids and alkalies carefully.

Reaction between Sodium Sulphate and Barium Chloride.

Materials Required:

Lab Procedure:

  • Take a small amount of barium chloride solution in a test tube and pour it into a conical flask.
  • Then take a small amount of sodium sulphate solution in another test tube and add it into barium chloride solution taken in the conical flask.
  • Stir the contents of the conical flask and keep it undisturbed for some time.
  • After some time decant the upper solution from the conical flask and add a small amount of dil. HCl to the precipitate in the conical flask.

Simulator Procedure:

You can select the reactions from the drop down list of the ‘Select Reaction’.

  1. Click on the bottle containing BaCl2 to pour it into the conical flask.
  2. Click on the bottle containing Na2SO4 to pour it into the conical flask containing BaCl2 .
  3. Stir the contents of the conical flask using a glass rod by clicking on the conical flask.
  4. You can see the inference by clicking on the inference icon.
  5. Now click on the conical flask to decant the upper solution into a beaker.
  6. Click on the bottle containing dil. HCl to pour it into the same conical flask.
  7. Click on the conical flask to shake it well.
  8. You can see the inference by clicking on the inference icon.
  9. You can click the ‘Reset’ button to redo the experiment.

Observation:

  • On adding sodium sulphate to barium chloride a white precipitate is immediately formed which is insoluble in dil.HCl.

Inferences:

  • Sodium sulphate chemically reacts with barium chloride in the form of their aqueous solution to form a white precipitate of barium sulphate.           
  • This reaction is a chemical change, as the products are entirely different from the reactants in chemical composition and chemical properties. 

Precautions:

  1. Use the chemicals judiciously.
  2. Keep the mouth of the test tube away from your face and also from other classmates.
  3. Handle the acids and alkali carefully.