Unit V: The Mole Concept

V.3. Multiple Conversions between Moles, Mass, Volume and Number of Particles

THE MIGHTY MOLE DIAGRAM

THE MIGHTY MOLE DIAGRAM

moles molecules atoms

L@STP

grams

Mighty Mole QuestionsGrams to Molecules conversion How many molecules are in a 2.62 g sample

N2O4

Plan: g mol molecules

1.71 x 1022 molecules

Mighty Mole QuestionsMolecules to Litres Conversion Find the volume occupied by 1.204 x 1026

molecules of SO2 at STP? Plan: molecules moles L

4480 L

Mighty Mole QuestionsGrams to Atoms Conversion Find the total number of atoms in a 300.0 g

glass of water. Plan: g mol molecules atoms date leaves

3.01 x 1025 atoms

Mighty Mole QuestionsGrams to Molecules 0.0342 g CH4 = ? Molecules Plan: grams moles molecules

1.29 x 1021 molecules

Mighty Mole QuestionsLitres to Molecules Conversion 54.3 L of NO2 = ? Molecules

1.46 x 1024 molecules

Mighty Mole QuestionsMolecules to Grams Conversion Find the mass of 3.68 x 1025 molecules of

NO2 (g)?

2.81 x 108 grams

Mighty Mole QuestionsMolecules Litres (STP) Conversion 1.35 x 1026 molecules of NH3 = ? L at STP

5.03 x 103 L

Mighty Mole QuestionsGrams to Atoms Conversion Find the number of atoms in a 286.0 g

sample of C3H8?

4.30 x 1025 atoms

Mighty Mole Questions

Find the number of “O” atoms in a 60.0L sample of N2O4

6.45 x 1024 “O” atoms

Hebden

Do Exercises 22 (a); 23 (a-d); 24 on pages 86-87 of Hebden

Do Exercises 36 (a); 37 (a) ; 38 (c); 42 (b, h, m) on pages 88-89 of Hebden

Assignment #9

DENSITY AND MOLES

Density is the mass per unit of volume

M

D V

THE MIGHTY MOLE DIAGRAM

moles molecules atoms

L@STP

grams

Density of Gases at STP

Density STP =

DSTP

Mass of 1 mole

Volume 1 mole

= Molar Mass

22.4

= MM (g/mol)

22.4 (L/mol) FOR FOR GASES GASES ONLYONLY

Density of Gases at STP

Find the density of P2O5 gas at STP?

DSTP

6.34g/L

= MM (g/mol)

22.4 (L/mol)

Density of Gases at STP

Calculate the density of O2 (g) at STP? DSTP

1.43 g/L

= MM (g/mol)

22.4 (L/mol)

Density of Gases at STP

The density of air is about 1.29 g/L. What is the density of Cl2 (g) at STP?

DSTP

3.17 g/L so Cl2 (g) is more dense than air

= MM (g/mol)

22.4 (L/mol)

Molar Mass From Density at STP DSTP = MM (g/mol)

22.4 (L/mol)

MM = DSTP x 22.4

Molar Mass From Density at STP An oxide of chlorine has a density of 3.013

g/L at STP

1. Find the molar mass of this gas

2. Determine the molecular formula for this gas

MM = DSTP x 22.4

Molar Mass From Density at STP An oxide of chlorine has a density of 3.013

g/L at STP

6.75 g/mol

MM = DSTP x 22.4

Molar Mass From Density at STP

ClO

ClO2

ClO3

Molar Mass From Density at STP A mystery gas has a density of 1.696 g/L at

STP. It is an element.

1. Find it’s molar mass

38.0 g/mol

MM = DSTP x 22.4

Molar Mass From Density at STP Given the molar mass of 38.0 g/mol

Guess the gas

Density of Solids and Liquids

M

D V

WHAT TO DO WHEN YOU DON’T HAVE A GAS!!

M = D x V

THE MEGA MIGHTY MOLE DIAGRAM

moles molecules atoms

L@STP

gramsD x V

M

D V

Example:Density Molecules Conversion The density of Boron (solid) is 2.34 g/mL. How many

molecules are there in a 60.0 mL chunk of boron? Plan: D x V g mol molecules

7.83 x 1024 molecules of Boron

ExampleAtoms Volume Conversion Liquid mercury has a density of 13.55 g/mL. Find the

volume occupied by 1.806 x 1027 atoms. (Hg is monatomic)

Plan: atoms molecules mol g volume

44413 mL or 44.4L

ExampleMoles Density Conversion A 5.00 mL sample of solid lead is known to contain 0.274

moles of Pb. Calculate the density of Pb. Plan: mol g density

11.35 g/mL

Example:Density MM (STP) 250.0 mL of a gas which is known to be a fluoride of

sulphur has a mass of 1.63 g at STP a) Find the molar mass

146.0g/mol

ExampleDensity MM (STP)(b) What is the molecular formula for the gas. (Calculated

Molar Mass = 146.0g/mol – fluoride of sulphur)

SF6 = 146.1 g/mol

ExampleD MM (STP) 1.25 L of disilane gas has a mass of 3.47 g. What is the

molar mass? (Assume STP) Plan: Density MM

62.2 g/mol

Example Density MM (STP) It is found that a 0.0263 mole sample of gas occupies a

volume of 482.0 mL. Calculate the molar volume in L/mol.

18.33 L/ mol

Hebden

Do Exercises 25, 27, 28 and 29 on pages 88 of Hebden Do Exercises 40 (e), 41 (a, f, h, k), 42 (b, e, n) on pages

89 of Hebden Do Hand-In Density Worksheet

Mid-Unit Test

Mega Mighty Mole Diagram Mole Conversions