Mass Measurements In Chemistry. Calculating Formula Weight. I CAN calculate the formula weight (molar mass) of a compound from it’s formula. We’ve talked about the mass of atoms in terms of one or two….but these masses are very small .
Calculating Formula Weight
I CAN calculate the formula weight (molar mass) of a compound from it’s formula.
We’ve talked about the mass of atoms in terms of one or two….but these masses are very small.
To be practical for laboratory work, a standard of measure had to be derived so that mass quantities could be easily measured.
To that end, scientists created a unit called the ATOMIC MASS UNIT used to measure the mass of subatomic particles.
The mass of a proton or neutron was assigned a value of 1 atomic mass unit (amu).
To create a system of practical measurement, scientists used the atom CARBON-12 [6 P+ and 6 No] and assigned it a mass of 12 AMU.
Then they calculated the number of atoms required to make a mass of 12 grams of Carbon-12.
They found it took 6.022 x 1023 atoms of C-12 to have a mass of 12 grams. In turn, each element’s atomic mass required 6.022 x 1023 atoms to equal the same mass in grams.
1 atom of Oxygen 16 weighs 16 AMU .
6.022 x 1023 atoms of O-16 weighs 16 grams!
This number became very important in chemistry is known as:
The quantity of matter containing Avagadro’s Number of particles, such as atoms, molecules or formula units, is known as a:
When working in a lab setting, the MOLE is used to determine quantities of chemicals.
3 atoms Ca
2 atoms P
8 atoms O
From Formula From Periodic Table
1mole CaX 40.08g = 40.08 g
1 mole C X 12.011 g = 12.011 g
3 moles O X 15.9994 g = + 47.9982g
= 100.0892 g
= 100.09 g/mole
Sodium Potassium Permanganate Tetrahydrate