1.10 acids and bases Flashcards
what is a bronsted-lowry acid?
proton donors- release H+ when mixed with water
what does bronsted lowry theory say about H+ ions?
equation?
theyre never by themselves in water- theyre always combined with H2O to form hydroxonium ions (H3O)
HA(aq) + H2O (l) -> H3O+ (aq) + A(aq)
what is a bronsted- lowry base?
a proton acceptor
what do bronsted- lowry bases do in solution?
equation?
grab hydrogen ions from water molecules
B(aq) + H2O(l) -> BH+(aq) + OH-(aq)
what does it mean that acids and bases can dissociate in water?
they break up into positively and negatively charged ions
what is a strong acid/ base?
dissociates almost completely in water- nearly all H+ ions will be released
what is a weak acid/ base?
dissociate only very slightly in water- only a small number of H+ ions are formed.
an equilibrium is set up which lies well over to the left
what happens when an acid is added to water?
equation?
the water acts as a base and accepts the proton
HA(aq) + H2O <-> H3O+(aq) + A-(aq)
what is the equation for water dissociating?
simplified?
H2O(l) + H2O(l) <-> H3O+(aq) + OH-(aq)
H2O (l) <-> H+ (aq) + OH-(aq)
where does the equilibrium lie for the dissociation of water?
well to the left as it only dissociates a small amount
what is Kw?
eq for dissociation of water lies so left that there is so much water compared to ions that conc of water is seen as constant
so, multiply expression for Kc of dissociation of water by [H2O], you get a constant- the ionic product of water (Kw)
Kw=
[H+][OH-]
when does Kw change?
when temp changes
what happens to Kw when dealing with pure water?
in pure water, theres always 1 H+ for 1 OH- so you can say that Kw= [H+]^2
what is the equation for calculating pH?
pH= -log10[H+]
