Acids and bases Flashcards
Acids and bases
what is a Brønstead-lowry acid
is a proton donor (H+ ion)
what is a Brønstead-lowry base?
is a proton acceptor
HCL (aq) + H2O (l) –> H3O+ + CL-
Explain what each reactant and product in this reaction are, their roles?
HCl = Brønstead-lowry acid , proton donor
H2O = Brønstead-lowry base, proton acceptor
H3O+ = a conjugate acid of H2O
Cl- = conjugate base of HCl
What is a conjugate acid?
a conjugate acid is a species formed from a bronstead lowry base by the addition of a proton
What is a conjugate base?
a conjugate base is a species formed when a bronstead lowry acid by the loss of a proton
HNO3 (aq) + H20 (l) —> H3O+ + +NO3- (aq)
Explain what each reactant a product is in this reaction, and their roles?
HNO3 = Brønstead-lowry acid , proton donor
H2O = Brønstead-lowry base, proton acceptor
H3O+ = a conjugate acid of H2O
+NO3- = conjugate base of HNO3
what if forced to act as a base even if it is usually neutral?
whatever is least acidic is forced to act as a base, even if it is ‘usually’ neutral e.g water
what is a strong acid?
examples?
a strong acid is a fully dissociated (fully ionised) proton donator
e.g HCL, HNO3, H2SO4, H3PO4
What symbol do we use to represent a fully ionised proton donor?
→ (arrow symbol)
What is a weak acid?
a weak acid is a partially dissociated (ionised) proton donator
e.g all carboxylic acids,
What symbol is used to represent a partially ionised proton donor?
use ⇌, (reversible reaction)
e.g HCOOH + H20 –> HCOO- + H3O+
what is a monoprotic acid?
Give examples?
a monoprotic acid donates one H+ per molecules
e.g HCL, HF, HNO3, HCOOH
what are the two general ways of representing monoprotic acids?
HA and HX
What is a diprotic acid?
Give examples?
a diprotic acid donates two H+ per molecule
e.g H2SO4 and all dicarboxylic acids
the reaction of diprotic acids in water occurs in two steps, what are the two steps? Use H2SO4 + H20 as an example
step 1: lose the first H+
Step 2: loose the second H+
Step 1: H2SO4 (aq) + H2O (l) –> HSO4- (aq) + H3O+ (aq)
step 2: HSO4- (aq) + H2O (l) –> SO42- (aq) H3O+ (aq)
Overall: H2SO4 (aq) + 2H2O (l) –> SO4- (aq) + 2H3O+ (aq)
what is a triprotic acid?
Give examples?
a triprotic acid donates three H+ ions per molecule
e.g H3PO4
explain the reaction of triprotic acids in water, what are the three steps? use H3PO4 + H2O as an example?
Step 1: H3PO4 (aq) + H2O (l) –> H3PO4- (aq) + H3O+ (aq)
step 2: H2PO4- (aq) + H2O (l) –> HPO4^2- (aq) + H3O+ (aq)
step 3: HPO4^2- (aq) + H2O (l) –> PO4^3- + H3O+ (aq)
Overall: H3PO4 (aq) + 3 H20 (l) –> 3H3O+ + PO4^3- (aq)
what is the pH scale?
nemerical scale between -1 and 15, that can be used to measure the pH of any solution
What is the pH?
the pH tells us the exact [H+] , concentration of hydrogen ions in a solution
pH = -log10[H+]
Calculate the pH of strong monoprotic acid of
a) 0.125 mol dm^-3 of HCL
pH = 0.90
Calculate the pH of strong diprotic acid of:
a) 0.100 mol dm^-3 of H2SO4
pH = 0.70
How do we calculate the [H+] concentration from the pH?
us the equation [H+] = 10^-pH
Calculate [H+] of a solution with a pH of 2.14?
0.00724 mol dm-3