Give reasons:
1. In the laboratory preparation of HCl acid from NaCl and conc. H2SO4, the residual salt formed at temperatures above 200oc itforms a hard crust and sticks to the glass( I know it does but I don't know why?)
2. In the fountain expt. to demonstrate the high solubility of HCl gas in water , dry HCl gas is filled in the round bottom flask.
3. Iron sheets are cleaned with HCl acid befor dipping into molten zinc for galvanizing.
Give reasons:
1. In the laboratory preparation of HCl acid from NaCl and conc. H2SO4, the residual salt formed at temperatures above 200oc itforms a hard crust and sticks to the glass( I know it does but I don't know why?)
2. In the fountain expt. to demonstrate the high solubility of HCl gas in water , dry HCl gas is filled in the round bottom flask.
3. Iron sheets are cleaned with HCl acid befor dipping into molten zinc for galvanizing.
1) The reaction proceeds as,
H2SO4 + 2 NaCl -------> 2 HCl + Na2SO4
Formation of hard crust of Na2SO4 which sticks to glass
2) When the HCl gas dissolves, water is sucked up to create a fountain, this creates a lot of vaccum which may lead to imploding of the flask. In R.B the pressure is equally distributed and hence is safer to conduct the exptt.
3) It is done to remove existing rust and prevent oxidation till galvanizing process begins.
1) The reaction proceeds as,
H2SO4 + 2 NaCl -------> 2 HCl + Na2SO4
Formation of hard crust of Na2SO4 which sticks to glass
2) When the HCl gas dissolves, water is sucked up to create a fountain, this creates a lot of vaccum which may lead to imploding of the flask. In R.B the pressure is equally distributed and hence is safer to conduct the exptt.
3) It is done to remove existing rust and prevent oxidation till galvanizing process begins.
