Unit 4 Acids and Bases Flashcards
What is a Bronstead-Lowry acid?
A proton donor
What is a Bronstead-Lowry base?
A proton acceptor
What would you use to find the pH of a strong acid?
-log10[H+]
What would you use to find the pH of a strong base?
Kw = [H+][OH-], then -log10[H+]
What is the value of Kw under standard conditions?
10^(-14)
What would you use to find the pH of water?
Kw = [H+]^2, then -log10[H+]
How would you find the pH of a weak acid?
By using Ka = [H+]^2 / [HA], then -log10[H+]
What does pKa equal?
-log10[Ka]
What would your method be for calculating the pH of a strong base and weak acid mixture?
Ka = [H+][A-] / [HA]
- Find the moles of HA.
- Find the moles of OH-.
- Find which is in excess.
- Factoring out moles which have reacted, use the remaining amount of HA or OH- and the relevant equations in order to find H+.
- -log10[H+]
How would you calculate the new pH of a buffer solution a) with acid added? b) with base added?
Use Ka = [H+][A-] / [HA]
a) Add the acid moles to HA in the equation and take them away from A-.
b) Take away the base moles from HA in the equation and add them to A-.
What is the range of phenolphthalein?
pH 8-10
What is the range of methyl orange?
pH 3-4
What is the definition of pH?
-log10 [H+]
What happens to a strong base in water?
Completely dissociates into H+ and A-
What happens to a weak acid in water?
Only partially dissociates, this means that a weak acid is a worse proton donor than a strong acid
