AP Chem CatalystAP Chem Catalyst AP Chem CatalystAP Chem CatalystCatalyst QuestionsCatalyst Questions

•Which one of the following substances exhibits the strongest intermolecular forces of attraction?A)CH4

B)CH3OH

C)C2H6

D)CH3Cl

E)C3H8

•Which one of the following substances exhibits the strongest intermolecular forces of attraction?A)CH4

B)CH3OH

C)C2H6

D)CH3Cl

E)C3H8

To Do & Homework To Do & Homework

Homework/Announcements: Practice Stoich Q’s Quiz on Monday on 3.1 and 3.2.

Homework/Announcements: Practice Stoich Q’s Quiz on Monday on 3.1 and 3.2.

Conversion Factors• To convert from one unit to another

we use a conversion factor.

I. Conversion Factors

Units You WantUnits You Have

Number with units given

New number with New Units

Conversion Factors Example – Convert $15 to cents

100Cents

1 Dollars15 Dollars

1500¢

Multi-Step Conversions• We may need to take multiple steps

to convert between units.• We must set up a series of conversion

factors so that all unnecessary units cancel one

Convert 3 hours to seconds

1 hour3 hours

10,800 sec60 min

1 min

60 sec

Table Talk• How many days are there in

525,000 seconds? (Note – 1 day = 24 h, 1 h = 60 min, and 1 min = 60 s)

White Board Races

Question 1

• Convert 500 minutes into seconds

Question 2• You have 5 dozen doughnuts,

how many doughnuts do you have (12 doughnuts = 1 dozen)

Question 3• You have 14 cups of water, how

many gallons of water do you have (1 gallon = 4 quarts; 1 quart = 4 cups)

Question 4• You have 32 cups of solution.

How many gallons do you have? (1 gallon = 4 quarts; 1 quart = 4 cups)

Question 5

• How many minutes are there in 1 year?

Question 6:

1. You have 42 dollars. You know the following conversions:

1 pound = $1.621 pound = 1.25 Euro

How many Euros do you have?

How High Can You Count?

602,200,000,000,000,000,000,000

• Atoms, ions, and molecules are so small, that a grain of carbon may have over trillions of atoms/particles.

• to make counting large numbers easier, scientist use the mole.

What is the mole?

The Mole• The mole is a unit that describes

the amount of particles that a substance has.

• Just like 1 dozen = 12 eggs, 1 deck = 52 card:

1 mole = 6.02 x 1023 particles

Avogadro’s Number

It’s a conversion factor!

6.022 x 1023 particles

mole

What does 1 mole look like?

He observed that

The # of C atoms in exactly 12 grams of Carbon-12 had 6.02 x 1023 atoms, so he let

1 mole of any substance = 6.02 X 1023 particles/ions/atoms/compounds/ions

How did Amedeo Avogadro come up with this conversion factor or relationship for counting particles?

Get it? • 1 mole of C = 6.02 x 1023 C

atoms

• 1 mole of H2O = 6.02 x 1023 H2O molecules

• 1 mole of Skittles = 6.02 x 1023 skittles

• 1 mole of electrons = 6.02 x 1023 electrons

What does 1 mole look like?

Example 1How many atoms are there 2.66 moles of sulfur? Hint: You will be using avogadro’s number b/c you want # of particles (atoms).

Example 2Find the # of molecules in 2.5 moles of sulfur dioxide (S02)

What does all this mean? Don’t just do the math.

• 2.5 moles of SO2 is like saying one dozen.

• 1 mole of any substance has 6.022 X 1023 molecules

• 2.5 moles of SO2 has 1.5 X 1024 molecules.

• Chemists can’t deal with 1.5 X 1024 molecules, it’s too large so we convert it into a smaller number.

Example 3How many moles are in 2.54 X 1022 Fe3+ cations?

You try these on line paper 4) How many ions are there in 0.187 moles of Na+ cations? Answer: 1.13 X 1023 ions5) How many atoms are there in 1.45 X 10-17 moles of arsenic? Ans: 8.73 X 106 atoms 6) How many compounds in 4.224 moles of acetic acid, C2H4O2? Ans: 2.54 X 1024 acetic acid compounds

7) How many moles of xenon does 5.66 X 1023 atoms have? Ans: 0.94 moles of Xe8) A sample of SO2 has 3.01 X 1023 molecules, how many moles is this? Ans: 0.5 mol SO2

Moles can be converted to mass

Molar Mass• Molar mass is the mass, in grams, of 1

mole of substance.• The molar mass is equal to the mass

listed on the periodic table • Units of Molar mass are g/mol

Molar Mass

Molar mass of carbon is 12 g / mol

Means 1 mol of C has 12 grams

Example 9…

What is the molar mass of Thorium? What does that mean?

Molar mass of Th = 232 g/ mol 1 mole of Th has 232 grams

You can find the mass from moles or # of

particles Example 10: You have 2.44 X 1024 atoms of carbon whose molar mass is 12.01g/mol according to your PT.A)How many grams of carbon is that?

Example 11:Find the mass of each substance in grams: A)2.11 x 1024 atoms of copper

You try - Example 12:Find the mass of each substance in grams: 3.99 x 1025 molecules of methane, whose MM = 16 g/mol

Example 13:You find the molar mass of an element using the atomic mass but what if you have a compound like glycerol, C3H8O3

You Try - Example 14:Use the answer from Ex 13 to find the amount of molecules in 47.5 g of glycerol.

Example 15: Find the molar mass of ZnCl2

You try - Example 16: Find the molar mass of (NH4)2SO4

Exit Slip (10 min)

A) Find the molar mass of toluene, C6H5CH3.

B) Find the # of moles in 7.51 g of toluene

C) How many covalently bonded compounds are found in 5 grams of toluene?