Post on 22-Dec-2015
A unit of measurement for counting atoms or molecules
1 Mole = 602 billion trillion 602,000,000,000,000,000,000,000 6.02 X 1023 (this is known as Avogadro’s
number)
Avogradro’s number is named in honor of Amedeo Avogadro (1776 – Amedeo Avogadro (1776 – 1856)1856)
He studied quantities of gases and discovered that no matter what the gas was, there were the same number of molecules present
We can count anything using the mole Example:
▪ 1 mole of M & M’s would stretch from here to the sun and back 200 billion times▪ * assuming m&m’s are 1 cm in diameter and the distance to the sun is 93
million miles
▪ Can you swim in1 mole of water?▪ 1 mole of H2O= about 1/3 of a cup (18 mL)
= 6.02 x 1023 C atoms
= 6.02 x 1023 H2O
molecules= 6.02 x 1023 NaCl formula unit
1 mole C
1 mole H2O
1 mole NaCl
* 1 mole = 6.02 x 1023 particles
Note: Particles could refer to atoms, molecules, formula units
* 1 mole = molar mass (g) of compound being used
MUST use dimensional analysis
MUST use the molar mass if grams are used in the problem
Be able to convert from Moles to atoms or molecules Moles to grams Grams to moles
How many atoms are in 0.500 mole of Al? Setup your problem using dimensional analysis:
* Multiply across and divide by the number at the bottom
0.500 mol Al
1 mol Al
6.02 x 10 23 atoms Al= 3.01 x 10 23
atoms Al
How many moles of Sulfur (S) are in 1.8 x 10 24 atoms of sulfur ? (Use dimensional analysis)
* Multiply across and divide by the number at the bottom
1.8 x 10 24 atoms S
6.02 x 10 23 atoms S
1 mol S= 2.99 mol S
1.) How many moles are in 5.22 x 10 24 atoms of H2O?
2.) How many molecules of NaOH are in 23 moles of NaOH?
How many grams are in 2.34 moles of Sodium hydroxide? You will utilize the molar mass you calculated and use
dimensional analysis.
2.34 mol NaOH
1mol NaOH
40.00 grams NaOH= 93.60 grams
NaOH
Molar mass of NaOH
How many molecules are in 42 grams of NaOH? Avogadro’s number: (6.02 x 1023 atoms, molecules or formula
units )= 1 mole)
42 grams NaOH
40.00 grams NaOH
1 mole NaOH
1 mole NaOH
6.02 x 1023 molecules NaOH
= 6.32 x 10 23 molecules NaOH
Molar mass of NaOH