Acid Base Equilibria

Question 0

What is the difference between strong acids and weak acids?

Answer 0

Strong acids donate all of their protons in aq solution whereas weak acids only donate some (in dynamic equilibrium)

Question 1

What is the Brönsted Lowry definition of a base?

Answer 1

A proton acceptor

Can coordinate bond with protons

Question 2

In the dynamic equilibrium of ethanoic acid, what species(‘) acts as a base?

Answer 2

H2O in the forward reaction (-> H3O+) and CH3COO- in the backwards reaction

Question 3

What is the definition of pH?

Answer 3

-log[H+(aq)]

Or the concentration of H+(aq) ions in a solution

Question 4

What is Ka measured in?

Answer 4

moldm-3

Question 5

Is Ka big or small with weak acids?

Answer 5

Small- little dissociation occurs

Question 6

In buffer solutions, what happens when you add an acid?

Answer 6

Concentration of H+ increases, so the reversible reaction shifts to the left, removing H+ ions by reaction with Ch3COO-

Question 7

In buffer solutions, what happens when you add a base?

Answer 7

It reacts with H+ ions so their conc decreases

Eq shifts to the right so more H+ are released from the acid

Question 8

When a buffer has equal concentrations of salt an acidic what is [H+] ?

Answer 8

[H+] is equal to the Ka for the acid

Question 9

When calculating the pH of buffers, what do you assume?

Answer 9

That all the salt dissociates but none of the acid dissociates.