Acid Base And Equilibria

Question 1

How to test if the precipitation reaction is complete? (2 marks)

Answer 1

1. Allow to settle the filtrate

2. Add a few drops of solution to see if precipitate forms

Question 2

Apart from reading errors, any other possible factor that may lead to incorrect value of titre obtained? (3 marks)

Answer 2

1. Jet not filled(air bubbles in burette)
   - value of titre larger than actual
2. Funnel kept in burette
   - value smaller than actual
3. Difficult to see colour change of indicator, so overshoot
   - value more than actual

Question 3

Explain difference between strong acid and concentrated acid

Answer 3

Strong is the one that fully dissociates in aqueous solution

Concentrated consists of a large quantity of acid and small quantity of water

Question 4

How to determine strength of acid by its pH value?

Answer 4

1. Find concentration of H+ ions

2. Since this is the same as the concentration of acid, it must have fully dissociated

Question 5

Calculate the pH value of 0.01M sulfuric acid.

Answer 5

-log(0.01*2)

=2

Question 6

When Kc<1, where is the eqm position?

Answer 6

Left

Question 7

How to test for presence of carbonate ions?

Answer 7

Add nitric acid (not HCl or H2SO4)

-fizzing-> present

Question 8

How to test if giant metallic or graphite?

Answer 8

Add acid and warm.

-fizzing -> metal present

Question 9

How to test if ionic or covalent if insoluble in water?

Answer 9

Heat with high temp

Test conductivity in molten state

Question 10

How explain the shift in eqm position due to pressure changes?

Answer 10

E.g, More gas molecules on the l.h.s. so equilibrium shifts to the
right as pressure is increased

Question 11

What is an acid?

Answer 11

A proton donor which dissociates to give H+ ions