Chapter 3

Question 1

Units of concentration

Answer 1

Mol dm ^-3
G dm ^-3

Question 2

What is the ideal gas equation?

Answer 2

pV = nRT
P= pressure (Pa)
V= volume (m ³)
N= amount of substance (mol)
R = 8.31J/molK (constant)
T= Temperature (K)

Question 3

Avogadro constant:

Answer 3

6.02x10²³mol

Question 4

What is the empirical formula?

Answer 4

The simplest whole number ratio of elements

Question 5

What does anhydrous mean?

Answer 5

A substance containing no water

Question 6

What does hydrated mean?

Answer 6

A substance that contains water

Question 7

What does water of crystallisation mean?

Answer 7

Water that is chemically bonded into a crystal structure
A compound that contains water of crystallisation is called a hydrated compound

Question 8

How to calculate percentage yield?

Answer 8

Percentage yield = actual yield/theoretical yield x 100

Question 9

How to calculate atom economy?

Answer 9

Atom economy = Mr of desired products/Mr of all products x 100

Question 10

Reactions with high atom economies:

Answer 10

Produce a large proportion of desired products and few unwanted waste products
Are important for sustainability as they make the best use of natural resources

Question 11

Finding the ratio of anhydrous salt to water in a compound:

Answer 11

Question 12

How to work out empirical formula from percentage composition:

Answer 12

Question 13

How to work out molecular formula from empirical formula:

Answer 13