Acid and base 2

what is a Bronsted-Lowry acid

an acid is a substance that donates a proton

what is a Bronsted-lowry base

a base is a substance that accepts a proton

what is hydrolysis

When a substance ( a salt) produced from an acid base reaction donates or accepts H+ from water

what is the nature of the salt prooduced when a strong acid and base react together

neutral

what is the nature of the salt produced when a weak base and strong acid react together

acidic salt

what is the nature of the salt produced when a weak acid and strong base react together

basic salt

what is the nature of the salt produced when a weak acid and base react together

neutral salt

what are neutral salt

CB of monoprotic acid, positive ions of group 1 and 2

how do you find pH

pH = -log ( H3O+)

how do you find [H3O+] from pH

10^-pH

what the value of Kw

1 X 10^-14

what does Kw equal

Kw= [ OH-] [ H3O+]

how do you find pH when given a base

-logx ( 10^-14/ [OH-]

What are the properties of an acid

• produces H3O+ in water

• taste sour and is corrosive

• turns litmus blue to red

• conducts electricity

what are the properties of a base

• produces OH- in water

• taste bitter and feels slippry and is corrosive

• turns litmus red to blue

• doesnt react with most metals

• conducts electricity

how to find Ka/Kb

[Products] / [ reactants]

what are the 3 strong acids

HCl, H2SO4 and HNO4

what is a strong acid and its Ka value

a strong acid completely ionises

• large Ka value >1

what is a weak acid and its Ka value

a weak acid partially ionises

• small Ka value <1

what are strong bases

ALL hydroxides, group 1 and 2 metal hydrides and oxides

what is a strong base and its Kb value

strong base completely dissociates

• large Kb value >1

what is a weak base and its Kb value

a weak base partially dissocaites

• small Kb value <1

what are the limitations with the Arrhenius model

• only applys to acid base behaviour in water

• doesnt explain substances like NH3 produce basic properties without having OH in formula

what is a polyprotic acid

acid with more than 1 H+ to donate

what happens to a polyprotic acid as it donates it H+s

Ka and acidic properties of subsequental acid decreases

what is an electrolyte

a substance that produces ions in an aqueous solution

what is a strong electrolyte

all dissolved molecules break up into ions in solution

what are examples of strong electrolytes

all ionic substances, strong acid and bases

what are weak electrolytes

only some of the dissolved molecules break up into ions

what are examples of weak electrolytes

weak acid and bases

what is a non-electrolyte

no molecules dissolved break up into ions

what is meant by strong and weak

relates to the level of dissociation and ionisation in water

what is meant by concentrated and diluted

relates to the amount of solute in a given area

what are the steps to calculate pH when 2 acids/ 2 bases are added together

• calculate moels of H+ for each acid/ OH- for each base and add together

• calculate concentration of H3O/ OH- in final

• find pH using formulas

what are the steps to calculate pH when adding strong acid and base

• calculate moles of H+ in acid and OH- in base ( at start)

• determine which is in excess as it effects pH

• calaculate moles of XS → large mole-smaller mole

• calculate concentration of XS

• find pH using formulas

what is buffer capacity

amount of strong acid/base that can be added before there is significant pH change

why do buffer solutions work

they work because weak acid and CB can co-exist without neutralising each other

what is a buffer system

a system where solutions have the ability to resist pH change when a strong acid or base is added

what do buffer systems consist of

weak acid + salt form of conjugate base

weak base + salt form of conjugate acid

what makes a buffer system have high buffer capacity

• contains high concentration of both weak acid and CB ( same for weak base)

• equal concentrations ( ensured none are limited)

what is the buffer system in blood and what effects the system

• carbonic acid and hydrogen carbonate ion buffer system

• effected by CO2 levels in blood

what is the pH range of blood

7.4 ± 0.05

why is water called amphoteric

it can act like a weak acid or base

self ionisation of water is endothermic or exothermic

endothermic

at what temperature can pH be measured at

25 degrees