Place two zinc granules in a test tube and pour 1-2 ml of hydrochloric acid into it. What are you watching?

Place two zinc granules in a test tube and pour 1-2 ml of hydrochloric acid into it. What are you watching? Write down the reaction equation. Cover your tube with the larger tube, slightly over the edge of the smaller tube. After 1-2 minutes, lift the large test tube up and, without turning it over, bring it to the flame of an alcohol lamp. What are you watching? What about the purity of the hydrogen you collect? Why was the hydrogen collected in an inverted tube?

Zn + 2HCl = ZnCl2 + H2

When hydrochloric acid is added to the zinc pieces, gas bubbles are released. This is hydrogen. A large test tube filled with hydrogen. When it is brought into the flame of an alcohol lamp, a clap is heard, a yellow flame appears. This is burning hydrogen. Water droplets appear on the walls of the tube:

2H2 + O2 = 2H2O.

If the hydrogen is pure (not mixed with oxygen in the air), a calm “pa” sound is heard;

if hydrogen is mixed with oxygen, becomes “contaminated”, then the sound becomes whistling, reminiscent of the barking of dogs. You cannot work with such hydrogen, it is explosive.

The hydrogen was collected in an upside down test tube because hydrogen is lighter than air.

If collected in a test tube in the normal position, then the air will displace hydrogen from the test tube, and hydrogen collection will not work.