Avocado or Avogadro? By: Sydney

            This week in Chemistry, we have been learning about the differences and similarities between formula and molecular weight as well as how to calculate molar mass. To fully understand the work we have been doing, it is first important to know the terms we are working with.

            Formula Weight is the sum of the atomic weights of the atoms in the chemical formula of the substance.

            Molecular Weight is the same as the formula weight when the chemical formulas between the two are the same.

In order to calculate the formula weight, it is necessary to find the atomic weight of each element. This is found above the element symbol on the periodic table.

With that in mind, we need to determine how many atoms of each element there are in the formula. For example, if we have the formula C₁₇H₁₉NO₃ , we can see that the subscript tells us there are 17 atoms of Carbon, 19 atoms of Hydrogen, 1 atom of Nitrogen, and 3 atoms of Oxygen. Now we can combine the information we have. Basically, we are going to multiply the number of atoms and the atomic weight of each element, then we will add all the atomic masses together to get one number as the total average atomic mass of the formula.

C₁₇H₁₉NO₃

27(12)+19(1)+14+3(16) = 285 amu

And voila! That is how we find the formula or molecular weight of a chemical formula.

Next, we will go over molar mass. Molar mass is the mass in grams of one mole of a substance. When working with molar mass, we use Avogadro’s number. Amedeo Avogadro was a physicist who was best known for his contribution to molecular theory. Personally, I think he looks kind of like a bird!

To find it, we use Avogadro’s number.

6.022 x 10²³

When you have grams that you want to translate to moles, they are the same numbers but they are labeled with different units of measurement.

16 grams = 16 moles

Regarding the information we have been studying this week, I think it is interesting that after using Avogadro’s number, the numbers are the same, yet the units of measurement are different. This must make it fairly easy when working with molar mass!

Here are some interesting facts:

            Avogadro’s full name is Lorenzo Romano Amedeo Carlo Avogadro di Quaregna e di Cerreto… that’s a really long name!

            Avogadro’s number is abbreviated as N_A.    

            There are only a little over 100 types of atoms!

Lastly, my question for the audience is, do you think Avogadro looks like a bird?