U2- Acids + Bases Flashcards
Bronsted-Lowry acid
a species that donates a proton, H+, during an acid-base reaction
general properties of acids
change colour of some indicators (exception eg is phenolphthalein indicator)
tend to be corrosive
sour
react w bases
pH<7
solutions can conduct electric current (bc covalent molecules can ionise and ions are free to move and carry e charge)
Bronsted-Lowry base
a species that accepts a proton, H+, during an acid-base reaction
alkali
soluble base that dissociates (splits up) hydroxide ions
general properties of bases
red litmus -> blue slippery bitter caustic (react w living tissue) react w acids pH>7 (alkali only) solutions can conduct electric current (alkali only)
ionisation
process by which a chemical species gains or loses an electric charge
dissociation
process by which a molecule separates into smaller particles
acid + alkali
[BAWS] salt (aq) + water (l)
acid + metal
[MASH] salt (aq) + hydrogen gas (g)
acid + carbonate
[CAWCS] salt (aq) + carbon dioxide (g) + water (l)
conjugate acid-base pairs: NH3 (aq) + H2O (l)
NH3 (aq) + H2O (l) –> NH4+(aq) + OH-(aq)
base. acid. conj acid. conj base.
amphiprotic substances
can either donate or accept a proton, H+
eg H2O, HSO4-
monoprotic, diprotic, triprotic and polyprotic
species that donates one/two/three/multiple protons, H+, during ionisation
strength of acid and bases
how readily an acid or base donates or accepts a proton, H+
strong acids + egs
undergo almost complete ionisation when added to water. Almost all acid molecules in solution will donate proton to form aqueous H+ ions good conductors eg sulfuric acid hydrochloric acid nitric acid
weak acids + eg
does not readily donate a proton, H+, in a solution. More reactant acid molecules present I'm solution that product of H+ ions hence <--> poor conductors eg ammonium ethanoic acid carbonic acid
strong bases
readily accepts a proton, H+ and dissociates to form OH- ions and a basic solution in an acid-base reaction eg O2- OH- HPO4 2- H- S2-
weak bases + eg
doesn’t readily accept H+ ions. More reactant base molecules present in solution than product of OH- ions hence <–>
eg ammonia
sulphate
ethanoate
strength vs concentration
strength of an acid/base relates to what proportion of its molecules will donate/accept a proton, H+
w/a
acid/base concentration depends on how many of those acid/base molecules were in the solution to begin with
pH and pH scale
measure of the concentration of H3O+ ions in solution
values of pH arranged on a logarithmic scale
[OH-][H3O+] = 10^-14 M^2
alkali
a soluble base
pH formulas
(dilute a solution by factor of 10 to increase/decrease pH by 1)
pH = -log [H3O+]
pH = 14 + log [OH-]
concentration from pH formulas
[H3O+] = 10 ^-pH
[OH-] = 10 ^pH-14
or
C1V1 = C2V2
ionic product of water
Kw = [H3O+] x [OH-] = 1 x 10^-14
constant value tf as [H3O+] increases, [OH-] must decrease to maintain constant and vice versa
