Acids and bases:

Question 1

Explain that equation using buffers

Answer 1

• when you increase the concentration of the acid the equilibrium shifts to the left
• the oh reacts with the H+ shifting the equilibrium to the left to overcome the loss of the H+ ions.
• The H+ concentration remains constant

Question 2

explain why a burette is used rather than a pipette?

Answer 2

• because it can deliver variable volumes

Question 3

Use the concept of electronegativity to justify why the acid strengths of ethanedioic and ethanoic acid are different.

Answer 3

• difference in structure of the two acids.
  Ethanedioc is R=COOH and the ethanoic acid is R=CH3
• the inductive effect
  The ethanediol acid has 2 very electronegative O2 atoms and a negative induced effect. The ethanoic acid has a =ve inductive effect.
• how the polarity of OH affects acid strength.
  The O–H bond in the ethanedioic acid is more polarised therefore disassociated more to H+ ions. Ethanedioic acid is stronger than ethanoic acid.

Question 4

Titration curves: if you add an acid to a base

Answer 4

you start from the base.

Question 5

Why would is the end point not clear enough to use an indicator. STRONG ACID/WEAK BASE

Answer 5

• gradual change in ph
• ## you have to add several drops of the indicator Na0H