How do you measure hydrogen gas in an experiment?

Question

Because hydrogen gas is insoluble in water, is that why we can measure the volume of hydrogen gas (i.e. with a gas syringe, gas jar, etc)?

Also, in an experiment when hydrogen gas is produced, does the hydrogen gas occupy the space not occupied by water? or does it combine with the water?

I would appreciate your answers, thank you!

Answer 1

you're absolutely right that hydrogen gas is effectively insoluble in water. this is because the hydrogen-hydrogen bond is nonpolar and water is polar.

in experiments when hydrogen gas is produced it floats on top of all other gasses and especially the water from which it was produced. here i'm imagining hydrolysis with electricity where hydrogen is produced at the anode. an air-filled inverted cup above the anode will collect hydrogen gas as it displaces the air inside the cup.

hydrogen molecules will not combine with water molecules. it nucleates at a surface defect on the anode and then grows in size until its bouyancy overcomes the stickiness (i believe determined by the surface tension of the water) with which it is attached to the anode.