Unit 7 Notes Part 2

Unit 7 Notes: Part 2
Equivalences to Conversion Factors

Equivalences to Conversion factors

An equivalence is a when two numbers equal each other. Such as:

●1 dollar = 4 quarters

●1 dozen eggs = 12 eggs

●1 mole A = # g A

●1 mole A = 6.022 x 10²³ atoms/molecules/formula units A

Equivalences to Conversion factors

An equivalence is a when two numbers equal each other. Such as:

●1 dollar = 4 quarters

●1 dozen eggs = 12 eggs

●1 mole A = # g A

●1 mole A = 6.022 x 10²³ atoms/molecules/formula units A

Conversion Factors take equivalences and make them into fractions.

1 mole C = 12.01 g C

1 mole C = 6.022 x 10²³ atoms C

1 mole C

or

12.01 g C

1 mole C

or

6.022 x 10²³ atoms C

12.01 g C

1 mole C

6.022 x 1023 atoms C

1 mole C

Relating Mass to Moles to # of Atoms using Dimensional Analysis

How do we convert among particles, moles and grams?
ALWAYS START WITH WHAT _________ IS GIVEN.

●There are 6.23 moles of Al.

○How many grams of Al are there?

○How many molecules?

●There are 111.7 g of Fe.

○How many atoms?

Relating Mass to Moles to # of Atoms using Dimensional Analysis

How do we convert among particles, moles and grams?
ALWAYS START WITH WHAT NUMBER IS GIVEN.

●There are 6.23 moles of Al.

○How many grams of Al are there?
6.23 mol Al x 26.98 g Al= 168 g Al

1

1 mole Al

Multiple Choice

Calculate the molar mass of AuCl₃

• 96 g

• 130 g

• 232.5 g

• 303.3 g

Multiple Choice

Find the mass of 5.82 mol of MgCl₂. Round to the nearest tenth.

• 554 g

• 436.8 g

• 55.2 g

• 555.9 g

Relating Mass to Moles to # of Atoms using Dimensional Analysis

How do we convert among particles, moles and grams?
ALWAYS START WITH WHAT NUMBER IS GIVEN.

●There are 6.23 moles of Al.

○How many grams of Al are there?
6.23 mol Al x 26.98 g Al= 168 g Al

1

1 mole Al

○How many molecules?
6.23 mol Al x 6.022 x 10²³ molecules Al= 37.5 x 10²³ = 3.75 x 10²⁴ molecules Al

1

1 mole Al

●Must fix the scientific notation!

●Apply significant figures!

●Give units!

Multiple Choice

How many elements are included in 2HNO₃?

• 4
• 3
• 7
• 6

Multiple Choice

How many molecules are in 9.4 moles of AlCl₃?

• 5.66
• 5.66x10²⁴
• 0.705
• 1.25x10²³

Relating Mass to Moles to # of Atoms using Dimensional Analysis

How do we convert among particles, moles and grams?
ALWAYS START WITH WHAT NUMBER IS GIVEN.

●There are 6.23 moles of Al.

○How many grams of Al are there?
6.23 mol Al x 26.98 g Al= 168 g Al

1

1 mole Al

○How many molecules?
6.23 mol Al x 6.022 x 10²³ molecules Al= 37.5 x 10²³ = 3.75 x 10²⁴ molecules Al

1

1 mole Al

●There are 111.7 g of Fe.

○How many atoms?
111.7 g Fe x 1 mole Fe x 6.022 x 10²³ atoms Fe= 12.04 x 10²³ = 1.204 x 10²⁴ atoms

1

55.85 g Fe

1 mole Fe

1 mole A = # g A
1 mole A = 6.022 x 10²³

atoms
molecules
formula units

A

●Must fix the scientific notation!

●Apply significant figures!

●Give units!

Multiple Choice

How many molecules are in 1 mole of NaCl? 

• 6.02 x 10²³
• 58 
• 11
• 17

Multiple Choice

How many atoms are in 3 moles of ANY ELEMENT?

• Multiply 3 x 26.981 g/mol

• Multiply 3 x (6.02 x 10²³) = 1.806 x 10²⁴ atoms

• 13 g/mol

• 26.981 g/mol

Multiple Choice

How many atoms of carbon are in 6.00g of carbon?

• 1.20x10²⁴atoms C
• 6.02x10²³atoms C
• 3.01x10²³atoms C
• 1.50x10²³atoms C

Multiple Choice

What is the mass of 1.2 x 10²⁴ atoms of C?

• 2.0 grams

• 24 grams

• 0.17 grams

• 1.4 x 10²⁵ grams