Q42 of 48 Page 15

When zinc metal is treated with a dilute solution of a strong acid, a gas is evolved, which is utilised in the hydrogenation of oil. Name the gas evolved. Write the chemical equation of the reaction involved and also write a test to detect the gas formed.

When zinc metal reacts with a dilute solution of strong acid [such as hydrochloric acid HCl], a salt (ZnCl2) is formed and hydrogen gas is evolved which is used in the hydrogenation of oil.



To test the presence of H2 gas, bring a burning splinter or a matchstick near the mouth of the test tube, you will see that the gas burns with a pop sound.


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40

Fill in the missing data in the given table.























































Name of the salt



Formula



Salt obtained from



Base



Acid



(i)



Ammonium chloride



NH4Cl



NH4OH



-



(ii)



Copper sulphate



-



-



H2SO4



(iii)



Sodium chloride



NaCl



NaOH



-



(iv)



Magnesium nitrate



Mg(NO3)2



-



HNO3



(v)



Potassium sulphate



K2SO4



-



-



(vi)



Calcuim nitrate



Ca(NO3)2



Ca(OH)2



-



 41

What are strong and weak acids? In the following list of acids, separate strong acids from weak acids.

Hydrochloride acid, citric acid, acetic acid, nitric acid, formic acid, sulphuric acid.

 43

In the following schematic diagram for the preparation of hydrogen gas as shown in the figure, what would happen if the following changes are made?



(a) In place of zinc granules, same amount of zinc dust is taken in the test tube.


(b) Instead of dilute sulphuric acid, dilute hydrochloric acid is taken.


(c) In place of zinc, copper turnings are taken.


(d) Sodium hydroxide is taken in place of dilute sulphuric acid and the tube is heated.

 44

For making cake, baking powder is taken. If at your home mother uses baking soda instead of baking powder in cake.

(a) How will it affect the taste of the cake and why?


(b) How can baking soda be converted into baking powder?


(c) What is the role of tartaric acid added to baking soda?