October 23rd was mole day….well at least the part from 6.02 am to 6.02 pm. I wonder how many of you let this day go by without even a thought? And you may ask, why should we celebrate an animal that digs holes in your lawn, or the dark spot on skin, or the massive stone structures at pier, or that undercover spy that steals secrets?

Well if you are a traveler in the science world, there is another kind of mole that is a very important concept to know about. The term mole in science comes from the German word “Molekül” (english: molecule) and the use of this term can be traced back to Willhelm Ostwald in 1894.

A mole in the language of science is the basic unit of measurement of all substances (atoms, molecules, ions, or particles, etc.). A mole is a constant number, known as Avogardo’s constant. This constant is defined as 6.022 x 10exp23, but it might be easier for you to think of it as 6.022 sextillion …that is right, there is such a number as sextillion and it is really big – a “thousand million million million”.

If you collected all 6.022 sextillion atoms in a mole of any substance and weighed them, you would get their molecular mass. Some of you may still have nightmares about having to learn the molecular masses of elements in the periodic table, but knowing what a mole of a substance weighs is very helpful. One thing it allows you to do is calculate how much of one substance will react fully with another.

Remember that low energy, happens at room temperature, reaction from my last blog using baking soda (sodium bicarbonate) and vinegar (5% acetic acid)? Well knowing the molecular masses of these substances, lets you calculate how much vinegar is needed to react with each gram of sodium bicarbonate.

Sodium bicarbonate has a molecular mass of 84.007 grams; pure acetic acid has a molecular mass of 60.052 grams . One mole of sodium bicarbonate will react with one mole of acetic acid – you can look this up, or just take my word for this.

So every 1 gram of baking soda will react with 0.715 grams of pure acetic acid (60.052/84.007).

But off-the-shelf vinegar is typically a 5% solution of acetic acid, so you would actually need 14.3 grams ((0.715 * 100)/5) of vinegar to react with 1 gram of baking soda. For those of you that like to think about liquids like vinegar as volumes, and since vinegar is mostly water, you can assume that 14.3 grams of vinegar is the equivalent of 14.3 mL (water has a density of 1 at room temperature)…again, you can look up or just take my word for it. But the end result is 1 gram of baking soda will react with 14.3 mL of your regular white vinegar.

Knowing about the molar mass of substances, has many practical uses in everyday life. It is the foundation of that delicate balance of chemical reactions that take place in our bodies, recipes we use for baking, and instructions on how to balance the pH of your pool water or the pH of your garden soil. But it will not tell how to stop moles from digging holes in your lawn…that is more like witchcraft than science.

“Dif-tor heh smusma”

— Judith Lockwood