chapter 4: acids and redox

which element in a compound is given the negative oxidation number

the more electronegative element is given the negative oxidation number

what’s the difference between a strong acid and a weak acid

a strong acid fully dissociates (releases all its H atoms into the solution as H+ ions) while a weak acid only partially dissociates

why are 4 examples of bases

ammonia

metal carbonates

metal hydroxides

metal oxides

what is a typical neutralisation reaction of an acid and metal oxide/hydroxide

acid + base → salt + water

what is an alkali

a base that dissolves in water to release OH- ions

what is a typical neutralisation reaction of an acid and metal carbonate

acid + metal carbonate → salt + water + carbon dioxide

what is a titration

a technique to accurately measure the volume of one solution that reacts exactly with another solution

what are 3 things titrations can be used for

finding the concentration of a solution

identifying unknown chemicals

finding the purity of a substance

what is used to accurately make a standard solution

a volumetric flask

what is a burette reading recorded to

the nearest half division with the bottom of the meniscus

what titres do you include in the mean titre

concordant ones (ones that are only 0.1cm³ apart)

what is an oxidation number

the number of electrons used when bonding to a different element

what is the oxidation number for elements

0

what is the charge of a compound equal to

the sum of the oxidation numbers

what is oxidation and reduction in terms of oxygen, electrons and oxidation number

oxidation - gain of oxygen/loss of electrons/increase in oxidation number

reduction - loss of oxygen/gain of electrons/decrease in oxidation number

what is disproportionation

a reaction in which the same element is reduced and oxidised

what is the oxidation state of fluorine and aluminium in compounds

-1 +3

what is the oxidation state of oxygen in compounds

+2 except in peroxides which is -1 or when bonded to F which is +2

what is the oxidation state of chlorine in compounds

-1 except when bonded with fluorine or oxygen

what is the oxidation state of hydrogen in compounds

+1 except in hydrides (group 1 or 2) where it will be -1