Using a periodic table, calculate the molecular weight of salicylic acid and aspirin.

Answer 1

First, you need to know the molecular formulas of each compound.

Then, find the Atomic Mass of each element found in the compound using the periodic table

Add them together.

Don't forget significant figures!

Salicylic acid - C₇H₆O₃

C - 12.01 u

H - 1.01 u

O - 16.00 u

Add using the frequency of each element in the compound:

12.01(7) + 1.01(6) + 16.00(3) =

138.13 g/mol

Aspirin (acetylsalicylic acid) - C₉H₈O₄

C - 12.01 u

H - 1.01 u

O - 16.00 u

Add using the frequency of each element in the compound:

12.01(9) + 1.01(8) + 16.00(4) =

180.17 g/mol