Pls help me with this..need answers ASAP..?

Question

In the preparation of oxygen, why is the first test tube of gas discarded? Why should the stoppered test tube of oxygen be set upwards?

Answer 1

Because in the reaction vessel or tubing is air, Then oxygen is produce it pushed out the air in the tubing into the first tube. So the first test tube contains air with some oxygen.

It should be kept upright in case it becomes pressured, with the cork facing upright an increase in pressure at a set limit blows the cork out. If the cork was facing down then the tube will rest on it. In this case if it does blow the test tube may explode sending glass every there. Its a case of flying cork vs flying shards of glass.

Answer 2

to determine if the oxygen fills up the tubes...