SI unit for amount of substance, defined as the number of atoms in exactly 12 g of carbon-12. One mole of a molecular compound contains Avogadro's number molecules and has a mass equal to the substance's molecular weight, in grams.
‘mole’ is often abbreviated as ‘mol’
Definition of Molar Mass
The mass of one mole of a material. For example, the molar mass of H2O is 18.015 g (obtained by adding twice the molar mass of hydrogen to the molar mass of oxygen).
The molar mass of an element can be found on the Periodic table. It is the decimal located below each element’s symbol.
Units: atomic mass unit (amu) or grams per mole (g/mol)
The number of particles in one mole, equal to 6.02214199 × 1023 mol-1 (± 0.00000047 mol-1).
Named for Amedeo Avogadro,
an Italian chemist and physicist (1776-1856)
Finding Molar Mass
Ex: H2O = 1 mol of Oxygen, 2 mol of Hydrogen
Multiply molar mass of each element by the number of moles of that element in the molecule: 1(15.9994) = 15.9994 and 2(1.00794) = 2.01588
Add the two numbers:
15.9994 + 2.01588 = 18.02 g/mol
Finding Molar Mass Cont.
Ex: NaOH = 1 mol of Sodium, 1 mol of Oxygen, 1 mol of Hydrogen
Multiply molar mass of each element by the number of moles of that element in the molecule: 1(22.990) = 22.990
1(15.9994) = 15.9994 and 1(1.00794) = 1.00794
Add the three numbers:
22.990 + 15.9994 + 1.00794 = 39.99734 g/mol
1 pair of aces = 2 aces
1 dozen apples = 12 apples 1 gross atoms = 144 atoms
1 mole of aces = 6.02x1023 aces
1 mole of apples = 6.02x1023 apples
1 mole of atoms = 6.02x1023atoms
1 mole = 6.02x10^23 atoms/ions/molecules/formula units
That equals around 602,000,000,000,000,000,000,000 atoms/ions/molecules/formula units!
1 mole = 22.4 Liters (L) of gas at STP (standard temp. and pressure)
1 mole = molar mass of element/molecule/compound/etc.
Converting from grams to moles:
( given mass of ___ ) x (1 mole of ___ ) = ___ moles of ___ ( molar mass of ___ )
Converting from atoms/molecules/ions/formula units to moles:
( given # of atoms of ___ ) x (1 mole of ___ ) (6.02x1023 atoms of ___ ) = ___ moles of ___
Mole Calculations Cont.
Converting from liters to moles:
( given volume in liters of ___ ) x (1 mole of ___ ) (22.4 liters of ___ ) = ___ moles of ___
Examples of Mole Calculations
45 grams N = ? Moles N
45 g N 1 mol N = 3.213 moles N 14.00674 g N
23.6 g H2O = ? Molecules H2O
23.6 g H2O 1 mol H2O 6.02x1023 molecules H2O 18 g H2O 1 mol H2O = 7.89x1023 molecules H2O
Examples of Mole Calculations Cont.
35 L of apple juice = ? moles of apple juice
35 L apple juice 1 mol apple juice 22.4 L apple juice = 1.56 mol apple juice
.07 moles of NaCl = ? grams NaCl
.07 mol NaCl 58.443 g NaCl = 4.091 g NaCl 1 mol NaCl
“Here, take my number. Of course, it's 6.02 X 10^23. I'm frickin' Avogadro! Ha! Get it?! It's my number!”
"Avogadro Cartoon 1." CSL Cartoon Stock. Web. 16 Mar 2011.