Acids and Bases Flashcards
What is the Bronsted-Lowry definition of an acid?
A proton donor
What is the Bronsted-Lowry definition of a base?
A proton acceptor
How do you calculate the pH? (Using [H+])
pH = -log10 [H+]
How can you use the concentration of H+ ions to work out pH?
[H+] = 10^-pH
HX –> H+ + X-
State whether this is a strong or weak acid, and give a reason why
Strong
DIssociates completely
How do you calibrate a pH meter?
Rinse probe thoroughly with deionised water, and shake gently to remove excess
Place probe in standard soln. of 4.00pH and record
Repeat process using standard ph 7.00 and 9.20 buffer soln.
Plot a graph of recorded pH (x) vs pH of buffer soln. (y)
Can be used to convert experimental readings into more accurate ones
What is Kw?
The ionic product of water
Kw = [H+][OH-] (x^2)
= 1.00 x 10-14 mol^2dm^-6
How do you work out the acid dissociation constant?
Ka = [H+][X-] / [HX]
How do you work out pKa?
pKa = -logKa
Describe step-by-step how you would work out the pH if it was strong acid vs strong base, and the acid was in excess
1) find mole of acid
2) find mole of base
3) which in XS
ACID IN XS
calculate conc. of [H+]
calculate pH using [H+]
Describe step-by-step how you would work out the pH if it was strong acid vs strong base, and the base was in excess
mole of acid mol of base XS? BASE IN XS calculate [OH-] use Kw to calculate [H+] calculate pH using [H+]
Describe step-by-step how you would work out the pH if it was weak acid vs strong base, and the acid was in excess
mol of acid mole of base XS --> ACID calculate moles of HA left and A- formed [HA]+[A-] (not always nec.) calculate [H+] conc using Ka calculate pH from [H+]
Describe step-by-step how you would work out the pH if it was weak acid vs strong base, and the base was in excess
mol of acid mol of base XS? --> BASE calculate [OH-] use Kw to calculate [H+] calculate pH using [H+]
What does acidic buffer contain?
A weak acid and the salt of that weak acid
What does basic buffer contain?
A weak base and the salt of that weak base
