Conversions involving molar mass and Avogadro’s number

 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 ( this is known as Avogadro ’ s number )

Amedeo Avogadro (1776 – 1856)  Avogradro ’ s number is named in honor of Amedeo Avogadro (1776 – 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)

 It is helpful in counting a large number of items  If the items are extremely small

= 6.02 x C atoms = 6.02 x H 2 O molecules = 6.02 x NaCl formula unit 1 mole C 1 mole H 2 O 1 mole NaCl

* 1 mole = 6.02 x 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 mole of Al?  Setup your problem using dimensional analysis:  * Multiply across and divide by the number at the bottom mol Al 1 mol Al 6.02 x atoms Al =3.01 x atoms Al

 How many moles of Sulfur (S) are in 1.8 x atoms of sulfur ?  (Use dimensional analysis)  * Multiply across and divide by the number at the bottom 1.8 x atoms S 6.02 x atoms S 1 mol S =2.99 mol S

 1.) How many moles are in 5.22 x 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 mol NaOH 1mol NaOH grams NaOH = grams NaOH Molar mass of NaOH

 How many molecules are in 42 grams of NaOH?  Avogadro’s number: (6.02 x atoms, molecules or formula units )= 1 mole) 42 grams NaOH grams NaOH 1 mole NaOH 6.02 x molecules NaOH =6.32 x molecules NaOH Molar mass of NaOH

1.) Determine the molar mass for Barium Hydroxide. 2.) How many moles are in 25.00g of barium hydroxide? 3.) How many grams are in 6.7 moles of barium hydroxide? 4.) How many formula units are in 35.00g of barium hydroxide? 5.) How many molecules are in 4.5 moles of barium hydroxide?