chapter 20 Flashcards
A Bronsted- Lowry acid
a proton donor
A Bronsted- Lowry base
a proton acceptor
conjugate acid-base pairs
a pair contains 2 species that can be interconverted by transfer of a proton
eg HCl–> Cl- conjugate base
Monobasic, dibasic & tribasic acids
- number of hydrogen ions in the acid that can be replaced per molecule eg HCl- monobasic CH3COOH- monobasic H2CO3- dibasic H3BO3- tribasic
redox reactions between acids and metals
acid + metal –> salt + hydrogen
eg 2H+(aq) + Zn(s) –> Zn2+(aq) + H2
neutralisation of acids with carbonates
acid + carbonate–> salt + water + carbon dioxide
eg 2H+(aq) + CuCO3(s)–> Cu2+(aq) + H2O(l) + CO2
2H+(aq) + CO2-3(aq)–> H2O(l) + CO2(g)
neutralisation of acids with metal oxides
acid + base –> salt + water
eg 2H+(aq) + MgO(s)–> Mg2+(aq) +H2O(l)
neutralisation of acids with alkalis
–> salt + water
H+(aq) + OH-(aq)–> H2O(l)
pH & [H+]
pH= -log[H+(aq)]
[H+(aq)]= 10-ph
-A pH of 1 has 10 times the conc of H+ ionises pH of 2
-to dilute from pH 1-4, dilution by 10x10x10=1000 times
pH of strong acids
[H+]=[HA]
a weak acid
partially dissociates eg CH3COOH(aq) H+(aq) + CH3COO-(aq)
Ka
= [H+] [A-]/[HA]
units= moldm-3 moldm-3/moldm-3
changes with temp
Ka and pKa
pKa= -logKa Ka= 10-pKa
strength of acid- Ka and Pka
the stronger the acid the larger the Ka value and the smaller the pKa value
the weaker the acid, the smaller the Ka value and the larger the pKa
Ka of weak acids
Ka= [H+]2/[HA]
