# Hydrogen burns...

• Sep 12th 2009, 07:53 AM
Mr Rayon
Hydrogen burns...
Hydrogen burns in oxygen to produce water.
a) Write a balanced equation for this reaction.

I got:

$2H_2 (g) + O_2 (g) ---> 2H_2O (l)$

however, in the answers it says

$2H_2 (g) + O_2 (g) ---> 2H_2O (g)$

- the difference being that the water is in a gaseous state rather than liquid. My question is, how do you know for sure to put $(g)$ after water in the right hand side of the equation? How do we know it remains a gas? When I think of H_2O I think of it in its liquid form.
• Sep 12th 2009, 08:00 AM
e^(i*pi)
It's something you have to learn really.

It is in a gas phase because the reaction between hydrogen and oxygen is highly exothermic and the heat generated is enough to ensure the water is gaseous. Of course it will condense in due course
• Sep 12th 2009, 03:58 PM
mr fantastic
Quote:

Originally Posted by Mr Rayon
Hydrogen burns in oxygen to produce water.
a) Write a balanced equation for this reaction.

I got:

$2H_2 (g) + O_2 (g) ---> 2H_2O (l)$

however, in the answers it says

$2H_2 (g) + O_2 (g) ---> 2H_2O (g)$

- the difference being that the water is in a gaseous state rather than liquid. My question is, how do you know for sure to put $(g)$ after water in the right hand side of the equation? How do we know it remains a gas? When I think of H_2O I think of it in its liquid form.

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