Quantitive Chemistry

Question 1

RFM =

Answer 1

Relative Formula Mass

Question 2

What is RFM?

Answer 2

Relative atomic mass of all the elements in a compound added together

Question 3

What is % mass of an element in a compound?

Answer 3

How much of a compound is made up by a particular element

Question 4

% mass of an element in a compound =

Answer 4

                     RFM of the compound

Question 5

How many particles in one mole?

Answer 5

6.02 x 10^23

Question 6

Mass =

Answer 6

Mr x Moles

Question 7

Mr =

Answer 7

Mass ÷ Moles

Question 8

Moles =

Answer 8

Mass ÷ Mr

Question 9

What is meant by the conservation of mass?

Answer 9

No atoms are gained or lost during a reaction (destroyed or created)

Question 10

What is a limiting reactant?

Answer 10

The reactant that is used up, stopping a reaction and leaving any other reactant in excess

Question 11

Gas volume in dm3 =

Answer 11

Moles of gas x 24

Question 12

Gas volume in cm3 =

Answer 12

Moles of gas x 24,000

Question 13

No. of moles (using gas volume in dm3) =

Answer 13

Volume ÷ 24 dm3

Question 14

No. of moles (using gas volume in cm3) =

Answer 14

Volume ÷ 24,000 cm3

Question 15

What is concentration?

Answer 15

The amount of substance in a certain volume of a solution

Question 16

What is the measurement of concentration?

Answer 16

mol/dm3 or g/dm3

Question 17

Moles =

concentration

Answer 17

Concentration x Volume

Question 18

Concentration =

Answer 18

Mass of solute(g) ÷ Volume of solvent(dm3)

Number of moles of solute(mol) ÷ Volume of solvent(dm3)

Question 19

What is atom economy?

Answer 19

The amount of starting material that ends up as useful product and how much ends up as waste

Question 20

Atom Economy =

Answer 20

Relative formula mass of desired product
————————————————————- x 100
Relative formula mass of all reactants

Question 21

How could you improve atom economy?

Answer 21

Find a desirable use for the wasteful products so the reaction give useful ‘byproducts’

Question 22

What is yield?

Answer 22

A measure of the ACTUAL amount of product formed

Question 23

Percentage Yield =

Answer 23

Mass of product ACTUALLY made
————————————————————– x 100
Maximum THEORETICAL mass of product

Question 24

Why may reactions not produce 100% yield?

Answer 24

The reaction was reversible - not all reactants react to make the product
The reaction didn’t finish
The reaction produced other products - side reaction such as reacting with gases in air or impurities in mixture
Lost product when separated from the reaction material - lost when filtering or transferring between containers etc.