Generation of hydrogen

Hydrogen is generated in a plastic pipette.

Materials
Test tube that fits to a single stand, single stand, plastic pipette, 5 mL syringe, hypodermic needle (0.8 mm/40 mm), isolation tape, cutting pliers, a pair of scissors or scalpel and tweezers.

Chemicals
4 mL 1:1 HCl, two Zn granules

Safety tips
Wear safety goggles! Syringe needle’s tip is sharp! You must be careful while piercing the pipette’s bulb.
Always use syringe needles with wide diameter (0.8 mm -1.2 mm) in order to avoid case of clogging when there is possible reaction of reagent with the needle metal.

Procedure

• Cut the pipette’s stem to make it shorter;
• Make a section to pipette’s bulb;
• Insert a needle into the pipette’s bulb;
• Take the tip of the needle out of the bulb trough the section and cut the tip with pliers;
•  Insert two zinc granules in the pipette’s bulb and close the section with isolation tape or sticky tape;
• Place the test tube on the stand and fill it with 1:1 HCl (up to 4/5 of the volume of the test tube or the volume should be enough to feel the pipette);
• Connect the syringe with the needle;
• The apparatus should be assembled as shown on Fig. 1.

Fig. 1. Apparatus for hydrogen generation

• Fill the pipette’s bulb with the acid from the test tube by bending the stem. During this, the needle and the syringe should stay connected on the pipette’s bulb;
• In another version a stopcock is used and the syringe could be connected later;
• The acid in contact with zinc will generate hydrogen which will be collected in the pipette’s bulb;
• When the pipette’s bulb is filled with gas, draw it in the 5 mL syringe and use it for some chemical experiments.