Question

A) write word equations and balanced equations for the reaction taking place when i. Dilute sulphuric acid reacts with zinc granules ii. Dilute hydrochloric acid reacts with magnesium ribbon

b.What is the difference between hydrated salts and anhydrous salts?

c.Give two important uses of washing soda.

Answer 1

A) $\bold{WHEN \: HYDROCHLORIC \: ACID \: REACTS \: WITH }$

I) Zinc

Hydrochloric acid, by its acidic properties will react with a metal zinc will give out a salt and hydrogen.

$Zn + 2HCl \longrightarrow ZnCl_2 + H_2 \uparrow$

II) Magnesium

Hydrochloric acid, by its acidic properties will react with metal magnesium to form a salt and hydrogen.

$Mg+ 2HCl \longrightarrow MgCl_2 + H_2 \uparrow$

B) -

$\bold{HYDRATED\: SALTS}$

The salts which contain fixed number of molecule water of crystallisation in loose chemical cimbination is called a hydrated salt.

Example :-

▶$CuSO_4.5H_2O [blue \: vitriol]$

▶$MgSO_4.7H_2O [Epsom salts ]$

▶$Na_2CO_3.10H_2O [Washing \: soda]$

$\bold{ANHYDROUS \: SALTS}$

The salts which donot have any water of crystallisation in loose chemical combination are known as anhydrous salts.

Example :-

▶$K_2SO_4 [Pottasim\: sulphate]$

▶$PbCl_2 [Lead \:chloride ]$

▶$NaNO_3 [Sodium \: nitrate]$

C) $\bold{USES \: OF \: WASHING \: SODA}$

◼It is used to remove permanent or temporary hardness of water.

▶When washing soda is mixed in hard water, the calcium , magnesium chlorides, sulphates and bicarbonate forms an insoluble precipitate which can be filtered out.

▶$Na_2CO_3 + CaSO_4 .\longrightarrow CaCO_3 \downarrow + Na_2SO_4$

▶$Na_2CO_3 + Ca(HCO_3) \longrightarrow CaCO_3 \downarrow + Na_2HCO_3$

◼It is uses in manufacturing soaps, paper and also in textiles industries.

◼Its used as reagents in laboratory.