Description DC passed through slightly acidic water evolves hydrogen and oxygen at the electrodes. Use test tubes to collecte samples of gas for about 5 minuts. Place a BRUNING splint into the tube with the most gas (keep tube inverted during test!) and a GLOWING (not burning ) splint into the other tube( don't touch the side of the tube). What happened? You will here a "POP!" from first tube and see more glowing from second tube.

Use the tongs to fill up the tubes with acidic water when it starts;
Acid can be either Sodium Thiosulfate (Na2 S2 O3) solution or dilute Sulfuric (H2 SO4). 5% of solution will be enough. The more concentrate acidic water the more fast chemical reaction;
The volume of gas from electrolysis is measured H2/O2 = 2/1;

Location 36F