Question

why water(H2O ) does not cathes fire even it has hydrogen which is an ideal fuel and oxygen that is supporter of combustion ?

Answer 1

The reason is simple. Any amount of money once spent can not be spent again.

That was an analogy the real reason is the following. Water is formed by burning Hydrogen gas with Oxygen gas. Burning is a chemical reaction, more specifically it is a red-ox reaction. In this type of reaction there is an electron donner (a reducing agent which itself gets oxidized upon donating electron) and an electron acceptor ( an oxidizing agent which itself gets reduced ). For the case of water, Hydrogen is the reducing agent and Oxygen is the oxidizing agent.

H2=2H+ + 2e-

(1/2)O2 + 2e- =O--

Here, money are those electrons that Hydrogen spends to be burnt and Oxygen receives the payment (electron) to burn Hydrogen. The end product is

H2+(1/2)O2=((2H+)+(O- -))= H2O

So we see that H2 in water is stripped of cash (electron) and can not spend the price (electron) to be burnt again.

That why water can not fuel further fire. When water is put on fire, it simply cuts O2 supply/hydrates/cools down the material being burnt thereby putting the fire off.

Answer 2

The reason is simple. Any amount of money once spent can not be spent again.

That was an analogy the real reason is the following. Water is formed by burning Hydrogen gas with Oxygen gas. Burning is a chemical reaction, more specifically it is a red-ox reaction. In this type of reaction there is an electron donner (a reducing agent which itself gets oxidized upon donating electron) and an electron acceptor ( an oxidizing agent which itself gets reduced ). For the case of water, Hydrogen is the reducing agent and Oxygen is the oxidizing agent.

H2=2H+ + 2e-

(1/2)O2 + 2e- =O--

Here, money are those electrons that Hydrogen spends to be burnt and Oxygen receives the payment (electron) to burn Hydrogen. The end product is

H2+(1/2)O2=((2H+)+(O- -))= H2O

So we see that H2 in water is stripped of cash (electron) and can not spend the price (electron) to be burnt again.

That why water can not fuel further fire. When water is put on fire, it simply cuts O2 supply/hydrates/cools down the material being burnt thereby putting the fire off.