Acid N Base

Question 1

CuO(s) + H2SO4(aq) → CuSO4(aq) +H2O(l)

Which reactant should be in excess?

Answer 1

CuO(s).
To ensure the acid is completely used up.
If not, the salt will be contaminated by the acid.

Question 1

CuO(s) + H2SO4(aq) → CuSO4(aq) +H2O(l)

Which reactant should be in excess?

Answer 1

CuO(s).
To ensure the acid is completely used up.
If not, the salt will be contaminated by the acid.

Question 2

Steps of obtaining soluble salt from:

s) + (aq) → (aq

Answer 2

1. Add (s) in excess reacts with (aq) to have a reaction mixture.
2. Filter the mixture to obtain the filtrate
3. Heat the filtrate till it becomes saturated.
4. Cool it down slowly in room conditions till crystals formed.
5. Filter the remaining solution to obtain the crystals.
6. Wash crystals with little and cold water & dry it with filter paper/ in oven.

Question 3

Y use limestone to reduce soil acidity rather than using NH3(aq)?

Answer 3

1. NH3(aq) has a pungent smell

2. NH3(aq) is volatile, ↑lost by evaporation & being washed away. ( H- bond)

Question 4

Y NaOH(aq) can’t be contacted with skin?

Answer 4

NaOH(aq) is corrosive, ppl may get skin burn if it is added to skin.

Question 5

Y copper(II) sulfate crystals change to white powder on heating?
(with aid of equation)

Answer 5

Water of crystallization gives molecules shape and color.

1. When the blue CuSO4•5H2O(s) is being heated, the water of crystallization from it is removed.
2. Anhydrous CuSO4(s) is white in colour.

Question 6

Production of slaked lime from limestone (Equation)

Answer 6

CaCO3(s)→ CaO(s) + CO2(g)

CaO(s) + H2O(l)→Ca(OH)(s)

Question 7

Ionic equation to show the use of slaked slime in industrial waste treatment

Answer 7

To neutralize acidic industrial waste before discharge.

Ca(OH)2(s) + H+(aq) → Ca2+(aq) + 2H2O(l)

Question 8

What should be used to wash and clean the conical flask before titration, distilled water/ solution?

Answer 8

Distilled water.

The distilled water remaining in the flask will not affect the amount of solute in the solution it is to hold.

Question 9

The washed conical flask not be dried before use, Y?

Answer 9

After washing a little water with remaining the conical flask.
This will not change the amount of solute present.

Question 10

What does a saturated solution mean

Answer 10

A solution contain the maximum amount of solute at a specified temperature.

Question 11

Why water should not be added to conc. H2SO4(l) in order to dilute the acid

Answer 11

1. Dilution of conc. H2SO4(l) is a highly exothermic process
2. The heat evolved can vaporize the water
3. → splashing out of the acid