NCERT CLASS 10-2021-SCIENCE-ACIDS,BASES AND SALTS- NOTES- PART 4- FAMILY OF SALTS

 

NCERT CLASS 10 SCIENCE-ACIDS,BASES AND SALTS- NOTES- PART 4- FAMILY OF SALTS

NCERT CLASS 10 SCIENCE-ACIDS,BASES AND SALTS- NOTES- PART 4- FAMILY OF SALTS

Now you will study some more about salts. As you already know that salt is formed by the combination of acid and base to form salt and water. So an activity can be performed.

 A list of salts is given to make a table. Write the formula of the various salts also. Identify from which acid or base it is formed. 

SALT	ACID	BASE
K2SO4	H2SO4	KOH
Na2SO4	H2SO4	NaOH
CaSO4	H2SO4	Ca(OH)2
MgSO4	H2SO4	Mg(OH)2
CuSO4	H2SO4	Cu(OH)2
Na2CO3	H2CO3	NaOH
NH4Cl	HCl	NH4OH
NaCl	HCl	NaOH
Mg(NO3)2	HNO3	Mg(OH)2

 

All of you can do this activity yourself simply. 

Write the names of the salts and rest you fill the table yourself. So it will make you perfect. You can learn the formula also without referring to the book.

 You make a table of the salts and make the salt solutions in water. Dissolve them and also find out which of the salts are soluble in water and which salts are not soluble in water.

So this activity can be performed in the lab and also you can test whether the salt solution is acidic or basic or neutral with the help of blue and red litmus paper.  Also you can find out the pH you using  the universal indicator paper.

  Salt of a strong acid and a strong base- neutral salts

Example 1-  NaCl is common salt. It is formed from HCl and NaOH.  NaOH is a strong acid and  HCl is also a strong acid. When you test it with blue litmus paper or red litmus paper, you will find that it is neutral.

 It neither changes the colour of blue litmus paper nor the colour of red litmus paper. It is neutral and also the pH is 7.

Example 2- KNO3 is formed from base KOH and acid HNO3. Both are strong. KOH is a strong base and HNO3 is a strong acid. And here also the salt is neutral as in the previous case.

So these are the salts of strong acid and strong base and they are called neutral salts ,which neither turn the colour of blue litmus paper or red litmus paper and pH is also 7.

  

Salt of a strong acid and a weak base – acidic salts

Example - aluminum chloride. It's formula is AlCl3. It is formed from a weak base aluminum hydroxide and a strong acid HCl. Now when it is tested with blue litmus paper, it turns the colour of blue litmus paper to red, showing thereby that the aluminium chloride salt solution is acidic in nature. So these are acidic salts.

 So acidic salts are formed by the combination of weak base and strong acid. pH value will be less than 7.

Zinc sulphate and copper sulphate are other examples of acidic salt.

Copper sulphate CuSO4 formed by weak base copper hydroxide and strong acid H2SO4.

 Salt of a strong base and a weak acid- basic salt

 Let us see the nature of sodium acetate? Its formula is a little bit complicated as you can see it (CH3COO)2Na. It is formed by the combination of  strong base NaOH and a weak acid acetic acid CH3COOH. 

When it is tested with red litmus paper, the colour of the red litmus paper changes to blue, showing thereby that the salt solution is basic in nature. pH value will be more than 7.

 So these are basic salts. There are some more examples of basic salts.

Sodium carbonate Na2CO3 formed by the combination of a strong base NaOH and a weak acid H2CO3 carbonic acid. It is also basic in nature.

Sodium hydrogen carbonate (baking soda) formula is NaHCO3 formed by the combination of a strong base NaOH and a weak acid H2CO3 ( carbonic acid). This is also basic in nature.

Family of sodium salts

 NaCl, CH3COONa, Na2CO3, NaHCO3

Sodium chloride ,sodium acetate ,sodium carbonate, sodium hydrogen carbonate. Sodium is common in families of sodium salts.

 Family of sulphate

Na2SO4, ZnSO4, K2SO4, MgSO4, CuSO4

Sulphate is common in Sodium sulphate , zinc sulphate, potassium sulphate, magnesium sulphate, copper sulphate.

Similarly sodium sulphate, sodium chloride, sodium nitrate, sodium carbonate are all sodium salts.

Carbonates- calcium carbonate, sodium carbonate, magnesium carbonate etc.

Hydrogen carbonates is a different family with members like sodium hydrogen carbonate, potassium hydrogen carbonate .

Sodium chloride, aluminum chloride or potassium chloride will form chloride family.

 So like this potassium nitrate. sodium nitrate will form a family of nitrates.

In the next portion we can learn about some important sodium salts and calcium salts.