The Mole What's a mole? In chemistry, a mole is a counting unit. What does that mean? –1–1 dozen = 12 units(ie eggs,donuts) –1–1 mole = 6.02x10 23 particles. –T–That's 602,000,000,000,000,000,000,000 particles! –6–6.02x10 23 is Avogadro's Number A mole is used to represent lots of particles –a–atoms –m–molecules(covalent compounds) –i–ions –I–Ionic compounds

If you have 3 particles of water, what do you have? You have 3 water molecules because H 2 O is molecular Covalently bonded compounds are called molecules If you have 4 particles of table salt, what do you have? You have 4 NaCl formula units becauseNaCl is ionic Ionic compounds are called formula units If you have 5 particles of gold, what do you have? You have 5 gold atoms because gold is an element Atoms are the unit for elements

The Mole How do you represent 6.02x10 23 in a scientific calculator? You can type 6.02x10^23 if you want... but there's a better way! -For graphing calculators: Type in 6.02 then the 2 nd button, then the “,” button, then 23 The calculator will display 6.02 E 23 This means “6.02x10 23 ” to the calculator. -For other calculators there is usually a key marked “E” or “EXP” that allows you to enter numbers in scientific notation.

How BIG is Avagadro's Number? ➔ 6.02x10 23 dollars would be enough to give every person on Earth $87 trillion. That’s $1 million a second for the next 2.8 years. ➔ A modern computer that can make up to 100 million counts per second would take almost 200 million years to count to 6.02x10 23 ➔ If 6.02x10 23 snowflakes fell evenly across the United States, the blanket of snow would cover every building in the country, including the tallest skyscrapers. ➔ If you could travel at the speed of light (186,000 mi/s in a vacuum), it would take you more than 100 billion years (longer than the Universe has been around) to travel 6.02x10 23 miles.

Mole to Particle Conversions Examples: How many molecules of methane are in 4.50 mol of methane? Remember: 1 mol CH 4 = 6.02x10 23 CH 4 molecules 4.50 mol CH 4 x6.02x10 23 molecules CH 4 1 mol CH 4 = 2.71x10 24 molecules CH x10 24 atoms Fe x How many moles of iron are in 2.39x10 24 iron atoms? 1 mol Fe = 6.02x10 23 Fe atoms 1 mol Fe 6.02x10 23 atoms Fe = 3.97 mol Fe

Molar Mass Individual particles are too small to count Can be counted if formula mass is known and mass in grams is measured Molar Mass = the mass in grams of 1 mole of a substance. AKA gram-formula mass Unique for every substance grams per mole (g/mol) Molar mass is equal to formula mass, but has the unit g/mol

Molar Mass Calculating Molar Mass Molar mass of an element = atomic mass, but in grams per mole Atomic mass of Fe = amu Molar mass of Fe = g/mol Every grams of iron contains 6.02x10 23 atoms! We can measure the mass of a sample of iron and then calculate how many atoms it contains.

Mole/Mass Calculations Examples: 1. What is the mass of moles of magnesium? Using Periodic Table: 1 mol Mg = 24.31g Mg 2. What is the mass of 5.80 moles of carbon monoxide? Molar mass of CO = 28.01g/mol mol Mg x g Mg 1 mol Mg = 6.08 g Mg 5.80 mol CO x g CO 1 mol CO = 162 g CO

Mole/Mass Calculations Examples: 1. How many moles would grams of neon be equal to? 1 mol Ne = 20.18g Ne 2. How many moles would grams of methane(CH 4 ) be equal to? Molar mass of methane = g/mol 50.45g Ne x 1 mol Ne 20.18g Ne = mol Ne 134.0g CH 4 x 1 mol CH g CH 4 = mol CH 4