C4- Acids and Redox

Question 1

What is an acid

Answer 1

An acid is a proton (H+ ion) donor

Question 2

What is a base

Answer 2

A proton (H+) acceptor

Question 3

Acid in water

Answer 3

When an acid is added to water it dissociates releasing H+ ions into solution

Question 4

Strong Acid

Answer 4

An acid that fully dissociates in solution

Question 5

Weak acid

Answer 5

An acid that partially dissociates in solution

Question 6

Alkali

Answer 6

base that dissolves in water releasing OH- ions into solution

Question 7

Bases examples

4

Answer 7

metal oxides

Metal carbonates

Metal hydroxides

Ammonia

Question 8

Dissociation of strong vs weak acid Equation

Answer 8

Reversible for weak single for strong

Equilibrium lies to the left for weak acid as not fully ionised

Question 9

Writing an ionic equation

Answer 9

Full balanced equation

Expand all ions
NOT solids

Cancel out same ions

Form ionic equation

Question 10

Method to make a standard solution

Answer 10

Weigh out a precise amount of a solid

Dissolve solid in beaker with distilled water, less than what will be made up in the volumetric flask

Transfer to volumetric flask

Fill to graduation line using distilled water, until the bottom of the meniscus lines up

Invert several times to mix the solution

Question 11

Titration procedure

Answer 11

Add a measured volume of one solution to a conical flask

Add the other solution to a burette, record its initial reading

Add a few drops of indicator to the conical flask

The tap on the burette is carefully opened and the solution added, portion by portion, to the conical flask until the indicator starts to change colour

As you start getting near to the end point, the flow of the burette should be slowed right down so that the solution is added dropwise

Multiple runs are carried out until concordant results are obtained
–>Concordant results are within 0.1 cm3 of each other

Question 12

Percentage uncertainty

Answer 12

per reading

uncertainty/ measured value x100

Question 13

burette reading

Answer 13

Since they are analogue instruments, the uncertainty is recorded to half the smallest marking, in other words to ±0.05 cm3

Read to the nearest half division

Question 14

OIL RIG

Answer 14

Oxidation is loss of electrons

Reduction is the gain of electrons

Question 15

oxidation number rule

Answer 15

123 FHOCl

order of priority of charges when calculated

Question 16

Reduction

Answer 16

Gain of electrons

decrease in oxidation number

removal of oxygen

Question 17

Oxidation

Answer 17

Loss of electrons

increase in oxidation number

addition of oxygen

Question 18

Oxidation state of elements

Answer 18

always zero

Question 19

Oxidising agent

Answer 19

substances that oxidise other species, gain electrons and are themselves reduced

Question 20

disproportionation réaction

Answer 20

the same element is both oxidised and reduced

Question 21

Weak acids examples

Answer 21

carbonic acid, H₂CO₃

citric acid , HOC(CH₂CO₂H)₂

ethanoic acid, CH₃COOH

Question 22

Strong acids examples

Answer 22

hydrochloric acid, HCl

nitric acid, HNO₃

sulfuric acid, H₂SO₄