The Mole Whats a mole In chemistry a

The Mole What's a mole? In chemistry, a mole is a counting unit. What does that mean? – 1 dozen = 12 units(ie eggs, donuts) – 1 mole = 6. 02 x 1023 particles. – That's 602, 000, 000, 000 particles! – 6. 02 x 1023 is Avogadro's Number A mole is used to represent lots of particles – atoms – molecules(covalent compounds) – ions – Forumula Units (ionic compounds)

The Mole � 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 Na. Cl formula units because. Na. Cl 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. 02 x 1023 in a scientific calculator? You can type 6. 02 x 10^23 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. 02 x 1023” 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. 02 x 1023 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. 02 x 1023 ➔If 6. 02 x 1023 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. 02 x 1023 miles.

Moles & Particles o If 1 mole = 6. 02 x 1023, then we can determine how many atoms(or molecules) are in stuff. o 1 mole : 6. 02 x 1023 Or 1 mol 6. 02 x 1023 particles o How many silver atoms are in 3 moles of Ag? (using dimensional analysis (factor method)) 3 mol Ag x 6. 02 x 1023 atoms Ag = 1 mol Ag Waitaminute… but why are moles on the bottom and Avogadro’s number on the top? Since 1 mol = 6. 02 x 1023, either one can be on top, we just choose the one that will cancel out the original unit.

Mole to Particle Conversions Examples: How many molecules of methane are in 4. 50 mol of methane? 4. 50 mol CH 4 x 6. 02 x 1023 molecules CH 4 1 mol CH 4 = 2. 71 x 1024 molecules CH 4 How many moles of iron are in 2. 39 x 1024 iron atoms? 1 mol Fe = 6. 02 x 1023 Fe atoms 2. 39 x 1024 atoms Fe x 1 mol Fe 6. 02 x 1023 atoms Fe = 3. 97 mol Fe

Molar Mass • • • Atomic measures the mass of atoms • Really small! Atomic Mass is based on Carbon-12 (12 C) • Very abundant, bonds with most everything • 1 amu = 1/12 the mass of 12 C • Too small to count Scientists decided that if 12 C = 12 amu, then 12 grams of carbon = 1 mole of carbon. • Which is equal to 6. 02 x 1023 atoms of carbon • 1 mole of anything = its atomic mass in grams 1 atom of oxygen = 16. 00 amu • 1 molecule of H 2 O = 18. 02 amu • 1 formula unit of Na. Cl = 58. 44 amu • 1 mole of oxygen = 16. 00 grams 1 mole of H 2 O = 18. 02 grams 1 mole of Na. Cl = 58. 44 grams

Moles & Particles • Molar Mass = the mass in grams of 1 mole of any substance. • AKA gram-formula mass • Unique for every substance • Unit: grams per mole (g/mol) Calculations with Molar Mass • What is the mass in grams of 2 mole of iron? • molar mass of Fe = 55. 85 g/mol 2 mol Fe x 55. 847 grams Fe = 111. 60 grams Fe 1 mol Fe

Mole/Mass Calculations Examples: 1. What is the mass of 0. 250 moles of magnesium? Using Periodic Table: 1 mol Mg = 24. 31 g Mg 0. 250 mol Mg x 24. 305 g Mg = 6. 08 g Mg 1 mol Mg 2. What is the mass of 5. 80 moles of carbon monoxide? Molar mass of CO = 28. 01 g/mol 5. 80 mol CO x 28. 01 g CO 1 mol CO = 162 g CO

Mole/Mass Calculations Examples: 1. How many moles would 50. 45 grams of neon be equal to? 1 mol Ne = 20. 18 g Ne 50. 45 g Ne x 1 mol Ne = 2. 500 mol Ne 20. 18 g Ne 2. How many moles would 134. 0 grams of methane(CH 4) be equal to? Molar mass of methane = 16. 05 g/mol 134. 0 g CH 4 x 1 mol CH 4 16. 05 g CH 4 = 8. 349 mol CH 4