Question

Using this equation for burning hydrogen in air: $ 2{{H}_{2}}(g)+{{O}_{2}}(g)\to 2{{H}_{2}}O(l).$ How many H and O atoms are shown on the left-hand side of the equation?

Answer 1

Hint: We are already provided with the equation. We just need a balanced equation and simply count the number of hydrogen and oxygen atoms. There is a little bit of stoichiometry.

Complete step by step solution:
We already know that; hydrogen burns in oxygen to form water. The flame is almost colourless. Mixtures of hydrogen and oxygen (or hydrogen and air) can be explosive when the two gases are present in a particular ratio, so hydrogen must be handled very carefully.
 $ 2{{H}_{2}}(g)+{{O}_{2}}(g)\to 2{{H}_{2}}O(l). $
Thus, there are 4 hydrogen atoms, but 2 hydrogen molecules, and 2 oxygen atoms, but 1 oxygen molecule on the left- hand side of the equation.
And on the RHS, there must necessarily be 4 hydrogen atoms and 2 oxygen atoms, because it is a balanced chemical equation.
This illustrates the principle of stoichiometry, which reflects the conservation of mass. If we start with 10 g of reactant, at most we can get 10 g of product.

Additional information:
We should know that when hydrogen reacts with oxygen by burning, the chemical energy is given out as heat. A fuel cell converts chemical energy directly into electrical energy – there is no heat. The overall reaction is: $ 2{{H}_{2}}(g)+{{O}_{2}}(g)\to 2{{H}_{2}}O(l). $ with electrons being exchanged from the cathode to the anode.

Note:
We already know that hydrogen has the highest calorific value so it can be considered as the best fuel but it is highly inflammable so it is difficult to store, transport and handle so it is used as a fuel only where it is absolutely necessary.
Also, hydrogen can be pumped into a vehicle's fuel tank just like gas. You can fill up quickly, the same way you would with gas or diesel. And once it has a full tank, a fuel-cell vehicle can travel just as far as a gas vehicle.