pH, Acids & Bases Flashcards
What do acids and bases, respectively, have a tendency to do?
Acids have a tendency to lose a proton and bases have a tendency to accept a proton.
What is the equilibrium equation for acids and bases?
AH + B A- + BH+
What do the following, from the equilibrium equation, represent?
- AH
- B
- A-
- BH+
- an acid
- a base
- the acid’s conjugate base
- the base’s conjugate acid
When water behaves as a base what happens?
It accepts H+ and forms a hydronium ion (H3O+).
When water behaves as an acid what happens?
It loses a proton and forms a hydroxide ion (OH-).
What is pH?
It’s a measure of the acidity of a solution.
The pH of a solution depends on what two things?
- the concentration of the acid/base in the solution
2. the type of the acid/base in the solution
What does the pKa value tell us?
It tells us how acidic (or not) a given hydrogen atom in a molecule is i.e. how likely it is that a hydrogen atom is released.
What is pKa?
It is the pH at which a group has lost half of its hydrogens.
True or False: an acid is a substance that increases the concentration of hydronium ions (H3O+) in a solution.
True
How far do strong acids dissociate in water?
Strong acids completely dissociate in water.
How far do weak acids dissociate in water?
Weak acids only partially dissociate in water.
True or False: a weak acid dissociates as the pH increases.
True
What is the status of the acid if the pH is 2 units or more below the pKa?
The acid is approximately 100% undissociated i.e. < 1% dissociated.
What is the status of the acid when the pH = pKa?
The acid is 50% dissociated.
