The odor of a smelly shower drain can be eliminated by removing debris from the drain. Discarding the odor-causing material in the garbage outside the home ensures the smell does not invade other areas. Boiling water dissolves oils and grease deposited on the sides of the pipe in the drain, which add to the smell.
Luckily for us, Nernst derived an equation that allows us to determine at what point the two forces (chemical and electrical gradients) balance each other - in other words, at what point we have an ionic equilibrium.
Notice that the Cl- was canceled out from the Net Ionic Equation, because it really isn't playing an important part of this reaction. It is just there to balance out the charge because you can't have an ion just by itself -- you must always pair an ion with another one of opposite charge so that the overall charge is zero.