Sulphur Dioxide

Sodium metabisulfite or sodium pyrosulfite  = Use Sodium Sulfite anhydrous

Add 2/3 spatula of Sodium Sulfite, add sufficient (4/5Cm)  of HCl 2.0 M and boil. insert collecting tube into the Poly-stop bottle with Distill water to collect the gas. test with Blue Litmus Paper for acidity(Turn purple/Red) when ready(Wet one with few drop of water to test the gas leaving the bottle. at the and you can dip it (Dry one) into the poly-stop bottle to test it acidity(Purple/red)