Unit 3 - Quantitive Chemistry

Question 1

What is avagadros number

Answer 1

6.02x 10 to power of 23

Question 2

What is a mole

Answer 2

Amount of a substance

Question 3

Equation relating volume, mass and Mr

Answer 3

Volume = (mass / Mr) x 24
At room temp (20)

Question 4

Equation for concentration

Answer 4

Concentration = mass in g / volume in dm3

Question 5

How to covert g into dm3

Answer 5

Divide by 1000

Question 6

Atom economy equation

Answer 6

Mr of desired products / Mr of all reactants x 100

Question 7

Equation for percentage yield

Answer 7

(Mass of product actually made / theoretical mass produced) x 100

Question 8

Why will the percentage yield not be 100%

Answer 8

Lose materials when transferred from one container to another , some will always get left behind

Question 9

How do you get from g/dm3 into mol/dm3

Answer 9

Divide by the Mr

Question 10

Explain difference between pipette and burette

Answer 10

Pipette measure fixed volume
Burette measures variable volume (drop by drop)

Question 11

How do you get from the number of particles to the number of moles

Answer 11

Times by avagadros number

Question 12

Ways to work our moles using energy

Answer 12

Energy required / energy for one mole = moles

Question 13

Why is percentage yield not 100%

Answer 13

Practical losses during experiment such as during pour or filtering
Side reactions occurred
Incomplete reactions in which some reactants do not react to form the product

Question 14

Name 3 strong acids

Answer 14

Hydrochloric, nitric, sulphuric,

Question 15

Name 3 weak acids

Answer 15

Carbonic acid, citric acid and ethanoic acid

Question 16

What is ph of a solution the measure of

Answer 16

Concentration of H + ions

Question 17

Explain why an acid can be described as both strong and dilute

Answer 17

Strong because completely ionised in aqueous solution and dilute because small amount of acid per unit volume

Question 18

What conditions has to occur for one moles of any has a volume of 24 dm3

Answer 18

Room temp and pressure

Question 19

What does inert mean

Answer 19

Unreactive

Question 20

Why should electrodes be inert

Answer 20

to avoid any unwanted chemical reactions with the electrodes themselves

Question 21

What happens at the cathode (talk about electrons)

Answer 21

Gain electrons

Question 22

What happens at the anode (electrons)

Answer 22

Lose electrons

Question 23

What is the limiting reactant

Answer 23

the reactant that is all used up in the reaction

Question 24

What does it mean when a reactant is in excess

Answer 24

reactants that are not used up when the reaction is finished are called excess reagents

Question 25

Equation to work out volume using just moles

Answer 25

Volume = moles x 24

Question 26

Colour change of phenolphthalein

Answer 26

Colourless in acid to pink in alkali

Question 27

Why use a white tile in the titration RPA

Answer 27

So you can see the colour change easier

Question 28

What type of reaction is a titration

Answer 28

Neutralisation