"H2O is combined to make water. When you agitate water it adds O. I understand if the O were to combine with t

Question

Example: Fish sometimes die if the water is still. If agitated, they thrive. So, "H2O is combined to make water. When you agitate water it adds O. I understand if the O were to combine with the H2O, it would become hydrogen peroxide, Ques: If so, why does it not combine?

Answer 1

OK.

There are two different things going on here.

When atomic oxygen forms a chemical bond with water, a new compound called hydrogen peroxide forms. Conditions for this reaction are not present in the usual situations of mixing atmospheric oxygen with water under typical environmental conditions.

When oxygen gas (O2 molecule) dissolves in water (just as CO2 dissolves in soda), sometimes that is referred to as "combined" with water, However, this combination is in the sense of a mixture or solution rather than about the formation of a new chemical bond.

Many fish species require a certain minimum level of dissolved oxygen in the water to survive. However, too much oxygen in the water, such as might happen below a dam spillway, can actually be toxic to fish.

Answer 2

Because the bonds between Hydrogen and oxygen in water are strong. To make hydrogen peroxide you would need to break one of these bonds and then join the two oxygens and rebuild the hydrogen oxygen bond again. This takes more energy than you can add by agitation of the water.

Fish can die in still water because the oxygen dissolved in the water is too little for them to get from the water via their gills.

There is a difference between dissolved oxygen and the oxygen that makes up the wate molecules. Fish can use dissolved oxygen but cannot liberate oxygen bound into water molecules.

Answer 3

Fish need oxygen gas (O2) in a high enough solution in the water.

On a sunny day in still water a lot of plants will grow using up the oxygen.
By spraying water in the pond you will add oxygen gas:
a) the fresh water contains oxygen gas
b) oxygen from the air is pushed into the water by the flow

So there are no chemical reactions in the water.

Answer 4

The reason is that the O-O bond in hydrogen peroxide is very weak meaning that any hydrogen peroxide formed in the fish tank is unstable and quickly breaks down back into water and oxygen gas.

Answer 5

Mere agitation does not provide enough energy for H2O2 to be formed. The oxygen (O2) molecule would have to be split and that requires a lot of energy. Oxygen is dissolved in water in the form of O2 not O.