Chemical Equilibrium Flashcards
For the general reaction:
aA + bB ⇌ cC + dD
What is the equilibrium expression?
K = [C]c [D]/[A]a [B]b
(lower case are powers)
Which factors does the equilibrium constant depend on?
Reaction temperature
Which factors are the equilibrium constant independent of?
Concentrations and pressure
What is the value of Kw at 25°C ?
Approx. 1 x 10 ^(-14)
What is the Brønsted-Lowry definition of acids and bases state?
That an acid is a proton donor and a base is a proton receptor.
What happens to strong acids and strong bases in an aqueous solution?
They completely dissociate into ions
What happens to weak acids and weak bases in an aqueous solutions?
They partially dissociate into ions.
Name 3 strong acids?
- hydrochloric acid
- sulfuric acid
- nitric acid
What is a buffer solution?
A solution in which the pH remains approximately constant when small amounts of acid, base or water are added.
What does an acidic buffer consist of?
A weak acid and one of its salts (made from a strong base)
What does a basic buffer consist of?
A weak base and one of its salts
Explain how an acidic buffer solution maintains its pH even in the presence of added acids/bases?
When a small amount of acid is added the salt provides the conjugate base which can absorb excess hydrogen ions.
When a small amount of base is added the weak acid provides hydrogen ions which can be removed.
How does a basic buffer solution maintain its pH?
The weak base removes excess hydrogen ions when an acid is added.
A conjugate acid is provided by the salt and supplies hydrogen ions when these are removed.
