Q.7 What happens (4 marks)
a) when electricity is passed through brine? Write
chemical equation for it.
b) Chlorine gas is passed through dry slaked lime.
c) Carbon dioxide gas is passed through lime water.
d) NaOH solution is heated with zinc granules.what happen when electricity is passed through brine write chemical equation for it
Answers
Explanation:a) Brine : It is the concentrated solution of sodium chloride. When an electric current is passed through the brine that is sodium chloride then the hydrogen gas forms at negative electrode and chlorine gas at the positive electrode
b)When Chlorine gas is passed through dry slaked lime ,it is rapidly absorbed,forming bleaching powder or chloride of Lime. The reaction is: Ca(OH)2+Cl=CaOCl2+H2O. Also water is formed with bleaching powder
c)when CO2 gas is passed through lime water it turns milky due to the formation of calcium carbonate which formula is CaCO3. when excess of carbon dioxide is passed through calcium carbonate calcium hydrogen carbonate is formed and solution become colourless
d)When sodium hydroxide solution is heated with zinc granules then Sodium zincate and hydrogen gas are formed. The salt formed by the reaction between a base and a metal, the metal is present as a part of the Negative Ion . All the metals do not react with bases to form salt and hydrogen gas. When electric current passed through brine, hydrogen gas is evolved at the anode, chlorine gas is evolved at the cathode, and sodium hydroxide is formed in the electrolysing solution. These three co-products are all very useful chemicals.