Properties of Acids and Bases

Materials Required:

Procedure:

 To perform in real lab:

 Action of litmus solution with acid and base.

 

Experiment

Observation

Inference

Take a little amount of blue and red litmus solutions separately in two test tubes. Add few drops of HCl to each test tube using a dropper.

Blue litmus turns red.

HCl is an acid having pH value below 7.

Take a little amount of blue and red litmus solutions separately in two test tubes. Add few drops of NaOH to each test tube using a dropper.

Red litmus turns blue.

NaOH is an alkali having pH value more than 7.

 

 
The evolution of hydrogen gas can be seen by conducting the following experiments.

 

Experiment

Observation

Inference

Take some pieces of zinc metal in a boiling tube. Add few drops of HCl into the boiling tube using a dropper. Then place a dropper with a fine jet on the mouth of the tube. Heat the boiling tube. Bring a burning matchstick near the mouth of the fine jet.

A gas is evolved. It extinguishes the burning matchstick and burns itself with mild explosion and produces a popping sound.

The gas evolved is hydrogen which burns with mild explosion.

Take some pieces of zinc metal in a boiling tube. Add few drops of NaOH into the boiling tube using a dropper. Then place a dropper with a fine jet on the mouth of the tube. Heat the boiling tube. Bring a burning matchstick near the mouth of the fine jet.

A gas is evolved. It extinguishes the burning matchstick and burns itself with mild explosion and produces a popping sound.

The gas evolved is hydrogen which burns with mild explosion.

Action of HCl on solid sodium carbonate

Experiment

Observation

Inference

Take a small quantity of solid sodium carbonate in a flask. Then add distilled water into it. Cork the flask with a double bore cork and insert a thistle funnel into the flask. Then place a beaker containing lime water near the flask. Then insert one end of the delivery tube into the flask and the other end into the beaker. Now add HCl into the flask through the thistle funnel and observe the change in colour of the lime water.

A gas is evolved which turns lime water turns milky.

The gas produced is carbon dioxide due to the action of HCl on Na2CO3, which turns lime water milky.

Action of NaOH on solid sodium carbonate

Experiment

Observation

Inference

Take a small quantity of solid sodium carbonate in a test tube and add a little of NaOH solution into it. Then shake the test tube well. Then add few drops of phenolphthalein into the test tube.

The solution in the test tube turns pink.

Both NaOH and Na2CO3 are alkali so they do not react but form alkaline solution. Phenolphthalein gives pink colour in an alkaline medium.

Simulator Procedure:

You can select the sample using ‘Select the sample’ drop down list.
You can select the reactant by clicking on the corresponding icon.


Litmus solution (For Acid and Base)

  • Drag the dropper towards the beaker and dip it in the sample to suck the sample solution.
  • Drag the dropper containing sample towards the test tube containing red litmus solution to pour the sample.
  • Again drag the dropper towards the beaker and dip it in the sample to suck the sample solution.
  • Drag the dropper containing sample towards the test tube containing blue litmus solution to pour  the sample.
  • You can see the colour change of the litmus solution due to the addition of different sample.
  • You can verify your result and can see the inference by clicking on the correct icon given under ‘Result’.
  • Click on the 'Reset' button to restart the test.

Zinc metal (For Acid and Base)

  • To pour the sample into the test tube containing zinc metal, drag the beaker towards the test tube.
  • To close the test tube, drag the single bored cork (in which a fine jet tube is inserted through the hole) towards the test tube.
  • Click on the knob of the burner to turn it on.
  • You can see that gas bubbles are evolved from the test tube.
  • Now, drag the burning match stick over the fine jet tube.
  • The flame dips out with a mild explosion.
  • You can verify your result and can see the inference by clicking on the correct icon given under  ‘Result’.
  • Click on the 'Reset' button to restart the test.

Solid Na2CO3 (For Acid)

  • To pour sample into the flask containing  mixture of solid sodium carbonate and distilled water, drag the beaker towards the thistle funnel.
  • You can see that gas bubbles are evolved from the flask and that turns lime water milky.
  • You can verify your result and can see the inference by clicking on the correct icon given under ‘Result’.
  • Click on the 'Reset' button to restart the test.

Solid Na2CO3 (For Base)

  • To pour sample into solid sodium carbonate, drag the beaker towards the test tube.
  • To pour phenolphthalein into the mixture of solid sodium carbonate and the sample, drag the beaker towards the test tube.
  • You can verify your result and can see the inference by clicking on the correct icon in the ‘Result’ part.
  • Click on the ‘Reset’ button to redo the experiment.

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

Precautions:

  1. Take small quantities of zinc, HCl and NaOH for their reaction, otherwise large amount of hydrogen produced may cause explosion.
  2. To hydrogen burning take a fine jet.
  3. Add HCl to Na2CO3, only when apparatus is made carefully airtight.
  4. NaOH and HCl are injurious, handle these chemicals carefully.

So, try out all and observe the changes………………

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