TOPIC 5 - Formulae, equations and amounts of substance

Question 1

What is Avogrado’s number?

Answer 1

6.02x10²³

Number of atoms or molecules in 1 mole.

Question 2

What is the equation for number of moles, mass and Mr?

Answer 2

Question 3

What is the equation for number of moles, concentration and volume?

Answer 3

Question 4

What is the empirical formula?

Answer 4

Simplest whole number ratio of elements in a compound.

Question 5

How can you get an ionic equation from a normal equation?

Answer 5

1. Split soluble compounds into ions.
2. Remove spectator ions.
3. Balance.

Question 6

What is a displacement reaction?

Answer 6

A reaction where a more reactive element takes the place of a less reactive element.

Question 7

What is a precipitation reaction?

Answer 7

A reaction where a solid is produced from aqueous reactants.

Question 8

What is the equation for number of moles, volume and molar gas volume in gases?

Answer 8

Question 9

What is the value of the molar gas volume at room temperature and pressure? (293K, 101.3kPa)

Answer 9

24dm³mol^-1

Question 10

What is the value of the molar gas volume at standard temperature and pressure? (273K, 101.3kPa)

Answer 10

22.4 dm³mol^-1

Question 11

What is the ideal gas equation?

Answer 11

Question 12

What colour does phenolphthalein turn in Acid?

Answer 12

Colourless

Question 13

What colour does phenolphthalein turn in Alkali?

Answer 13

Pink

Question 14

What colour does methyl orange turn in acid?

Answer 14

Yellow

Question 15

What colour does methyl orange turn in alkali?

Answer 15

Red.

Question 16

What are concordant results? (when talking about titres)

Answer 16

Results withn 0.1cm³ from each other.

Question 17

How can we calculate uncertainty from measuring apparatus?

Answer 17

Uncertainty is half the smallest increment the equipment can measure.

Question 18

What is the equation for % yield?

Answer 18

Question 19

What is the theoretical yield?

Answer 19

The amount of product produced assuming no products are lost and all reactants react together.

Question 20

What is the equation for atom economy?

Answer 20

Question 21

What are the advantages of high atom economy?

Answer 21

• Less waste - better for the environment.
• Raw materials are used more efficiently.
• Less by-products so less time and money spent in separating the desirable product.