Acids and Bases

Question 1

How does NH2 act as a base

Answer 1

Nitrogen lone pair accepts a proton

Question 2

Explain how a solution (glycolic acid and glycolate ions) can act as a buffer

Answer 2

Reversible reaction (HOCH2COOH  H+ + HOCH2COO-)
added alkali reacts with H+
(HOCH2COOH + OH- --> HOCH2COO- )
Equilibrium shifts to the right 
added acid reacts with ions 
(HCOCH2COO- + H+ --> HOCH2COOH)
Equilibrium shifts to the left

Question 3

How can a buffer be prepared (from ammonia and glycolic acid)

Answer 3

base reacted with EXCESS acid
(ammonia + excess glycolic acid)
Equation
(HOCH2COOH + NH3 –> HOCH2COO- + NH4+)

Question 4

What factor needs to be considered when deciding on a suitable indicator

Answer 4

the end point of the indicator / the equivalance point

Question 5

Explain whether dissociaton of water is exothermic or endothermic

Answer 5

endothermic because Kw increases with temperature