Moles, Molar Mass, & Unit Conversion

How do they determine the # of pages in a ream?

Do they count? 500 sheets

Do they mass the paper? 20 lbs or 9.071847 Kg

Which would be more accurate?

Overview

What is a Mole?

What is molar mass?

How is molar mass determined?

Unit conversion with molar mass.

What is a mole?

A mole is a number which can refer to atoms, molecules, or particles.

One mole = 6.02 x 1023 particles = Avogadro’s #

In equations, we abbreviate it as “mol.”

What is molar mass?

Molar mass is the mass of one mole of a substance.

e.g. 1 mol Li = 6.94 g Li

Practice:

What is the mass of one mole of Ni?

How is molar mass determined?

Knowing the average mass of substances allows us to count by weighing.

How many pages in a ream?

10 sheets = ???

1 ream = ???

What is molar mass?

Molar mass is the mass of one mole of a substance.

Practice:

What is the mass of one mole of Ni? 58.69 g Ni

What is molar mass?

Molar mass is the mass of one mole of a substance.

Practice:

What is the mass of one mole (the molar mass) of SO2?

What is molar mass?

Molar mass is the mass of one mole of a substance.

Practice:

What is the mass of one mole (the molar mass) of SO2? 32.07 g + 2x(16.00 g)=64.07 g SO2

What is molar mass?

Molar mass is the mass of one mole of a substance.

Practice:

What is the molar mass of Cu3(BO3)2?

What is molar mass?

Molar mass is the mass of one mole of a substance.

Practice:

What is the molar mass of Cu3(BO3)2?

3x(63.55 g)+2x(10.81 g + 3x(16.00 g)) = 190.65 g + 117.62 g = 308.27 g

Molar Mass Practice

Find the molar mass of NaBr.

Find the molar mass of (NH4)2CO3.

Find the molar mass of C6H12O6.

Molar Mass Practice

Find the molar mass of NaBr. 102.9 g/mol

Find the molar mass of (NH4)2CO3. 96.0 g/mol

Find the molar mass of C6H12O6. 180.0 g/mol

Unit Conversion with Moles

If we are given the # of moles, we can determine the number of grams.

1. Determine the molar mass.

2. Calculate the other apex.

g

mol g/mol

Unit Conversion with Moles

Practice: 16.04 g CH4 = ? mol CH4

Unit Conversion with Moles

Practice: 16.04 g CH4 = ? mol CH4

1 mol CH4 = 12.01 g + 4x1.008 g = 16.042 g CH4

Unit Conversion with Moles

Practice: 16.04 g CH4 = ? mol CH4

1 mol CH4 = 12.01 g + 4x1.008 g = 16.042 g CH4

16.04 g CH4 x (1 mol CH4 /16.042 g CH4 )

Unit Conversion with Moles

Practice: 2 mol Fe2O3 = ? g Fe2O3

Unit Conversion with Moles

Practice: 2 mol Fe2O3 = ? g Fe2O3

? g /mol Fe2O3 = 2x(55.85) + 3x(16.00)

= 111.7 + 48

= 159.7 g /mol Fe2O3

Unit Conversion with Moles

Practice: 2 mol Fe2O3 = ? g Fe2O3

? g /mol Fe2O3 = 159.7 g /mol Fe2O3

2 mol Fe2O3 x 159.7 g /mol Fe2O3 = 319.4 g Fe2O3

Unit Conversion Practice

How many moles are in 25.0 g of water?

Unit Conversion Practice

How many moles are in 25.0 g of water? 1.39 mol H2O

Unit Conversion Practice

How many grams are in 4.5 moles Li2O?

Unit Conversion Practice

How many grams are in 4.5 moles Li2O? 134.1 g Li2O

Homework

Review the section on molar mass (pgs. 130-136).

Do “Mole Practice”