4 Acids and Redox

formula of 4 common acids

HCl, H₂SO₄, HNO₃, CH₃COOH (ethanoic acid)

formula of 3 common alkalis

NaOH, KOH, NH₃

what do acids do in aqueous solution

release H⁺ ions

what do alkalis do in aqueous solution

release OH^- ions

explain strong and weak acids in terms of relative dissociations

strong acids fully dissociate

weak acids partially dissociate

ionic formula for neutralisation reaction

H⁺ _(aq) + OH^-_(aq) --> H₂O_(l)

describe neutralisation

the reactions of acids with bases (including carbonates, metal oxides and alkalis (water-soluble bases), to form salts

steps to prepare a standard solution

1. weigh a precise amount of solid

2. add solid to small volume of distilled water in a beaker and dissolve

3. add to a volumetric flask

4. rinse the beaker with distilled water and add the rinsings to the flask

5. make up to the bottom of the meniscus of the graduation line with more distilled water in volumetric flask

6. add stopper and invert flask a few times to mix contents

describe oxidation and reduction in terms of changes in oxidation number

increase in oxidation number = oxidation

decrease in oxidation number = reduction

disproportionation

a redox reaction in which the same element is both oxidised and reduced

acid def

• a proton donor

• gives off  H⁺ ions when dissolved in water

base def

• proton acceptor

• a compound that neutralises an acid to form a salt

alkali

a soluble base

releases OH- in aq solutions

strong acid def

a proton donor that fully dissociates in water

examples of strong acids

 HCl, H₂SO₄, H₃PO₄ (kinda), HNO₃

strong base def

a proton acceptor that fully dissociates in water

e.g. NaOH

weak acid def

a proton donor that partially dissociates in water

what kind of acids are weak

all organic acids

e.g. HCOOH methanoic acid

weak base def

a proton acceptor that only partially dissociates in water

weak base example

NH₃

acidic oxide

non-metal oxides

can donate protons when in water

basic oxide

metal oxides

can accept protons when in water

amphoteric

can react w acids and bases

example of an amphoteric compound

aluminium oxide Al₂O₃

amphiprotic

can donate and accept protons

example of amphiprotic compound

water, aluminium hydroxide Al(OH)₃

redox

a reaction where oxidation and reduction take place. a chemical element is both consumed and produced

weak acids/bases use what sign in their reaction

reversible reaction sign

describe oxidation state

the charge on an element in a compound if all bonds to that element are 100% ionic

oxidation state rules

elements are always 0

in compounds:

O = -2

H = +1

Grp1 = +1

Grp2 and Zinc = +2

how to find out the overall charge of a compound

the sum of the oxidation states

is the sign before or after the number in oxidation numbers

before the sign

special cases of oxidation numbers

H in metal hydrides = -1

e.g. NaH

O in peroxides = -1

e.g. H₂O₂

O bonded to F = +2

e.g. F₂O

modern name for nitrite NO₂^-

nitrate (III)

ox number of nitrogen in nitrite NO₂^-

+3

ox number of nitrogen in nitrate NO₃^-

+5

diprotic acid example

H₂SO₄

what kind of acids are good conductors of electricity and why

strong acids

• more ions in aqueous as more H+ dissociate

concentration has no correlation to the strength of the acid

when can u do a conductimetric titration

when there are no ions on one side of the reaction

graph for conductimetric titration

formula for sulfate (VI)

SO₄^2- sulfate

formula for sulfate III

SO₃^2- sulfite

formula for nitrate V

NO₃^- nitrate

formula for nitrate III

NO₂^- nitrite

formula for chromate VI

CrO₄^2-

formula for dichromate VI

Cr₂O₃^2-

wording for describing what has been oxidised/reduced by oxidation number

Cu in CuO has been reduced from +2 to 0 in Cu

• include element and compounds

• include oxidation number change

why is this reaction a neutralisation reaction

an acid has been neutralised by a base to form water

why is calcium nitrate a salt

the H+ ion in an acid has been replaced by a metal ion/Ca2+

what is a Cl with a ox state of 7 called

Chlorate VII