Question

What is the balanced equation when potassium reacts with chlorine gas?

Answer 1

`"2K(s) + Cl"_2("g")"` `rarr` `"2KCl(s)"`

Explanation:

Unbalanced equation

`"K(s) + Cl"_2("g")"` `rarr` `"KCl(s)"`

There are two chlorine atoms on the left-hand side (LHS) and one chlorine atom on the right-hand side (RHS). Add a coefficient of `2` in front of `"KCl"`.

`"K(s) + Cl"_2("g")"` `rarr` `"2KCl"`

There are now two atoms of chlorine on both sides. However, the `"K"` is not balanced. There are two `"K"` atoms on the RHS, and only one on the LHS. Place a coefficient of `2` in front of `"K"` on the LHS.

`"2K(s) + Cl"_2("g")"` `rarr` `"2KCl(s)"`

There are now `"2 K"` atoms on both sides and two chlorine atoms on both sides.

Notice that only coefficients were changed in the balancing process. Adding or subtracting subscripts are not allowed because that would change the identity of the substances.