In this problem, hydrogen combines with chlorine to from hydrogen chloride. This has been given to us in the from of a word equation as:
`"Hydrogen"+"Chlorine"to "Hydrogen chloride"`
Now, Formula of hydrogen is `H_(2)`
Formula of chlorine is `Cl_(2)`
And, Formula of hydrogen chloride is HCl
By, putting these formulae in the above word-equation, we get the following chemical equation:
Let us balance this equation now. If we look at this equation carefully, we find that there are two hydrogen atoms and two chlorine atoms on the left side but only one hydrogen atoms and one chlorine atom on the right side. Now, to have two hydrogen atoms and two chlorine atoms on the right side, we have to multiply HCl by 2 and write at as 2HCl. This gives us :
`" "H_(2)+Cl_(2)to 2HCl`
This is a balanced equation because it contains an equal number of hydrogen atoms and chlorine atoms in the reactants and products.
Hydrogen, chloride, are all gases, so we can write the above equation with state symbols as follows :
`" "H_(2)(g)+Cl_(2)(g)to 2HCl(g)`
