Virtual Experiments - Acids, Bases and Salts Notes | EduRev

Science Class 10

Class 10 : Virtual Experiments - Acids, Bases and Salts Notes | EduRev

The document Virtual Experiments - Acids, Bases and Salts Notes | EduRev is a part of the Class 10 Course Science Class 10.
All you need of Class 10 at this link: Class 10

Activity

Aim: To find ph of Salt.
Procedure

  • Collect the following salt samples: Sodium chloride, potassium nitrate, aluminium chloride, zinc.
  • Sulphate, copper sulphate, sodium acetate, sodium carbonate and sodium hydrogen carbonate.
  • Check their solubility in water.
  • Check the action of these solutions on litmus and find the pH using a pH paper.
     Which of the salts are acidic, basic or neutral?
  • Identify the acid or base used to form the salt.

Observations

Virtual Experiments - Acids, Bases and Salts Notes | EduRev

  • The pH value is greater than 7 at 25°C
Ques: You have been provided with three test tubes. One of them contains distilled water, and the other two contain an acidic solution and a basic solution, respectively. If you are given red litmus paper, how will you identify the contents of each test tube?
Activity:
  • Take a small amount of finely chopped onions along with some strips of clean cloth in a plastic bag.
  • Tie up the bag tightly and leave it as such in a refrigerator for a night. In the morning, take two of these strips and check their odour.
  • Now put a few drops of dilute HCl solution on one strip and a few drops of dilute NaOH solution on the other.
  • Rinse both the cloth strips with water and again check their odour and note down in your notebook.
  • You will see that onion will give different odour in HCl and NaOH.
  • You can repeat the activity by taking dilute vanilla essence. Smell dilute vanilla essence.
  • Now take some dilute HCl solution in one test tube and dilute NaOH solution in another test tube add a few drops of dilute vanilla essence to both the test tubes and shake well.
  • Check the odour once again.
  • You will feel different smells in both the test tubes.
  • Lastly, you can repeat the activity by taking clove oil in place of vanilla essence.
  • From this activity, we conclude that vanilla, onion or clove oil can also be used as olfactory indicators since these change their odour.

Activity
Aim: To study the reaction of acids, with metals.
Materials required: Granulated zinc, Dilute sulphuric acid, Boiling tube, Matchbox.

Procedure

  • Take about 5 ml of dilute sulphuric acid in a boiling tube.
  • Add a few pieces of zinc metal into it and place an inverted boiling tube over its mouth.
  • You can see the bubbles of hydrogen gas coming out of the mixture in the lower tube.
  • After a few minutes, remove the upper boiling tube (Keeping its mouth downwards) near to its mouth. What do you see?
  • The gas in the upper boiling tube burns with a blue flame producing the popping sound.
  • Repeat a similar experiment with different acids and a few other metals. Write down your observations.

Virtual Experiments - Acids, Bases and Salts Notes | EduRev

The reaction of Acids with Metals

Observation: Colourless, odourless gas is evolved. It burns explosively with a 'pop' sound.
Zn(s) + H2SO4 (dil) → ZnSO4 (aq) + H2(g)

Conclusion: Reactive metals react with dilute acid to liberate hydrogen gas. Metals which can displace hydrogen from dilute acid are known as active metals.
Example: Na, K, Zn, Fe, Ca, Mg etc.

Activity

Aim: To study the reaction of sodium carbonate and sodium hydrogen carbonate with dilute acids.

Materials required: Sodium carbonate (Na2CO3), Sodium hydrogen carbonate, Hydrochloric acid (dil.), Limewater, Boiling tubes, Delivery tube.
Procedure

  • Take about 0.5g of sodium carbonate in a boiling tube and 2-3 mL of freshly prepared limewater in another test tube.
  • Set a delivery tube, as shown in fig. given alongside. Add about 2mL of dilute hydrochloric acid into the boiling tube containing sodium carbonate.
  • A brisk effervescence is seen in the reaction mixture. Pass the gas evolved through limewater with the help of a delivery tube.
  • What do you observe? The limewater turns milky.
  • When an excess of carbon dioxide is passed, the milkiness disappears. Repeat the similar experiment with sodium hydrogen carbonate (NaHCO3), and if desired with other acids also.

Virtual Experiments - Acids, Bases and Salts Notes | EduRev

The reaction of Acids with Sodium Carbonate and Sodium Hydrogen Carbonate

Conclusion: All acids decompose carbonates and hydrogen carbonates with the liberation of carbon dioxide gas.

Activity

Aim: To study the reaction of dilute acid with metal oxides (or basic oxides).

Materials required: Copper (II) oxide, Dilute hydrochloric acid, Test tube.

Procedure

  • Take about 0.5g of copper (II) oxide (black in colour) in a test tube.
  • Add dilute hydrochloric acid dropwise with occasional shaking till copper (II)  oxide dissolve.
  • Note the colour of the solution. I not it bluish-green? It is the solution of copper (II) chloride.

Conclusion: Acids react with metal oxides to give the corresponding salt & water.
Activity

Aim: To study a reaction of an acid, say hydrochloric acid with an alkali or base.

Materials required: The hydrochloric acid solution, sodium hydroxide solution, phenolphthalein indicator, Boiling tube, dropper, trough.

Procedure

  • Take about 5 mL of a dilute solution of sodium hydroxide (NaOH) in a test tube. Add 2 drops of phenolphthalein indicator in it.
  • The solution in the test tube turns pink.
  • Now, add a dilute solution of hydrochloric acid (HCl) when the pink colour of the solution just disappears.
  • Now, add a drop of sodium hydroxide solution and shake the test tube to mix the solution. What do you see? The solution turns pink.
  • Add a drop of HCl solution to the solution in the test tube. The pink colour disappears.
  • Keep repeating the addition of sodium hydroxide and hydrochloric acid solution one after the other and watch the appearance and disappearance of pink colour.

Conclusion

  • This experiment shows that the addition of the HCl solution destroys the alkaline nature of NaOH.
  • On the other hand, the addition of the NaOH solution destroys the acidic nature of HCl.
  • That is, both NaOH and HCl appear to cancel the effect of each other.
  • Such a reaction between an acid and alkali is called neutralisation.
Activity

Aim: To find the characteristics common between acids and bases.

Materials required: Dilute hydrochloric acid, Dilute sulphuric acid, Dilute solution of sodium hydroxide, Ethanol, Glucose solution & Beaker, Carbon electrodes, Dry cells, bulb 1.5 V, Key.

Procedure

  • Take a beaker and place two carbon electrodes into it.
  • Connect the electrodes to a battery bulb through a key and a dry cell. Pour dilute hydrochloric acid into the beaker and press the key. 
  • Did the bulb glow? Perform a similar experiment with all the given solutions, and record your observations.

Virtual Experiments - Acids, Bases and Salts Notes | EduRev

Acid Solution in Water Conducts Electricity 

Observation

Virtual Experiments - Acids, Bases and Salts Notes | EduRev

Conclusion: The solutions of acids and bases are good conductors of electricity. The solution of glucose and ethanol are nonconductors of electricity.


Activity

Aim: To show that acids furnish H+(aq) ions only in the presence of water.

Materials required: Common salt, Conc. sulphuric acid, anhydrous calcium chloride, blue litmus paper, boiling tube, delivery tube packed with anhydrous calcium chloride.

Procedure

  • Take 0.5g of dry common salt in a dry boiling tube. 
  • Add a few drops of concentrated sulphuric acid over common salt in the boiling tube. What do you see? 
  • A colourless, irritating gas is evolved. 
  • Fit a cork carrying a calcium chloride packed delivery tube into the mouth of the boiling tube.
  • Bring a dry blue litmus paper near the opening of the calcium chloride tube. Observe, if there is any change in colour. Colour of the litmus paper remains unchanged. 
  • Now, bring a moistened blue litmus paper near the mouth of the calcium chloride tube. 
  • Do you observe any change in the colour of litmus paper? Yes, blue litmus has changed to red.

Conclusion

  • Dry HCl gas on coming in contact with dry blue litmus paper does not produce H+ ions, and hence the colour of the litmus paper does not change. So, we can say that separation of H+ ions from acid takes place only in the presence of water.
Activity

Aim: To show that water of crystallisation can be removed by heating.
Materials required: CuSO4.5H2O (Blue vitriol), boiling tube, burner, cork, delivery tube, test tube, clamp stand.

Procedure

  • Take 2 g of CuSO4.5H2O in a boiling tube fitted in a clamp stand. 

Virtual Experiments - Acids, Bases and Salts Notes | EduRev

Removing Water of Crystallisation

  • Observe its colour. Fit it with cork, and delivery tube bent at two right angles which dip into a test tube.
  • Heat crystals in a boiling tube. Observe vapours being condensed in the test tube.
  • Cool the crystals and add few drops of water into it 

Observation

  • Water vapours get condensed in a test tube, and the colour of blue crystals changes into white.
  • On adding water to anhydrous copper sulphate, it changes into blue again.

Virtual Experiments - Acids, Bases and Salts Notes | EduRev

Conclusion: Crystalline substances have water of crystallization which is lost on heating.

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