(BLUE) pH And Ka Flashcards
What is the definition of an acid and alkali/base
Acid : is a proton donor / accepts a lone pair of electrons
Base/alkali : is a proton acceptor / donates a lone pair of electrons
What is a conjugate acid-base pair
It is the base that is formed from an acid in a reaction e.g NH4+ to NH3 , strong acids produce weak bases and vise versa
What does amphoteric mean
Can act as both an acid and a base
What is the definition of a strong acid
A strong acid is an acid which fully dissociates (ionises) when it is dissolved in water
Strong acids have weak conjugate bases
What is the definition of a weak acids
Is an acid which only partially dissociates (ionises) when it dissolves in water
Weak acids have strong conjugate bases
Water is a weak acid it’s conjugate pair hydroxide is a very strong base
What colour methyl orange in
Acid and base
Acid : red
Base : yellow
What colour phenolphthalein in
Acid and base
Acid: colourless
Base:: bright pink
What colour bromothymol blue in
Acid and base
Acid : yellow
Base : blue
What colour bromophenol blue
Acid and base
Acid : yellow
Base : purple
How do you go from pH to conc of H+
[H+] = 10^-pH
What is the constant for Kw
1x10^-14
What is the equation for Kw
Kw= [H+][OH-]
What is the equation for Kc
Kc= product conc / reagent conc
What does p mean
-log
What is the equation of Ka
Ka= Acid dissociated conc x H conc / acid conc
What is the definition of enthalpy of neutralisation
The energy released when one mole of water is produced from an acid-base reaction at standard room temperature and pressure
Why do HCL and HNO3 have similar enthalpy of nutralisation
Because both HCL and HNO3 are monoprotic therefore releasing 1H+ , both strong acids therefore fully dissociate
Why does CH3COOH have a lower enthalpy of neutralisation than HCL
Ethanoic acid is a weak acid which means it does not fully dissociate
Also energy is used to break O-H bond which is Endothermic
Explain the increasing acidity of ethanoic acid —>benzoic acid —-> methanoic acid
CH3 donates e- density , which strengthens the O-H bond more, which makes it easier to loose the hydrogen
Explain the increasing acidity of chloroethanoic acid —-> tricholoroethanoic acid
Cl is very electronegative which pulls the e- density away from the O-H bond , weakening it
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Why does phenylamine have the lowest pH (weakest base)
Lone pair of e- on N delocalised into the pie system so not available to accept H+
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Why does dimethylamine have the highest pH
CH3 donates electron density therefore Lone pair of electrons on N more available to accept H+
