Acids, Bases and Salts

Which of the following is/are properties of alkalis.

I. They have pH greater than 7

II. They react with acids

III. They are soluble in water

• I, II and III

• I and II only

• II and III only

• III only

Sodium hydroxide is considered to be a strong alkali. Its aqueous solution would be expected to have pH of

• 1

• 2

• 9

• 14

Antacid powders would be expected to turn litmus

• red

• blue

• purple

• green

Baking powder turns universal indicator greenish blue. This shows that baking powder is

• weakly alkaline

• strongly alkaline

• weakly acidic

• strongly acidic

Why is sulphuric acid described as dibasic?

• Each molecule contains two OH^- ions.

• Each molecule can produce two hydrogen ions.

• Sulphur can form two acids, sulphuric acid and sulphurous acid.

• Sulphuric acid has usual properties of an acid, but is also a dehydrating agent.

Phosphoric acid H₃PO₄, behaving as a monobasic acid, ionises as

• H₃PO₄ (aq) --> 2H⁺ (aq) +HPO₄ ^2- (aq)

• H₃PO₄ (aq) --> H⁺ (aq) + H₂PO₄^- (aq)

• H₃PO₄(aq) --> 3H⁺(aq) + PO₄ ^3-(aq)

• H₂PO₄^-(aq) --> H⁺(aq) + HPO₄^2-(aq)

The oxide of a metal was found to react with hydrochloric acid and with aqueous sodium hydroxide. Which of the following is the best description of the oxide?

• Acidic

• Amphoteric

• Basic

• Neutral

Which of the above acids is MOST likely completely ionised?

• Acid P with a pH of 2

• Acid Q with a pH of 4

• Acid R with a pH of 3

• Acid S with a pH of 5

Acid P has a pH of 2.

Acid Q with a pH of 4.

Acid R with a pH of 3.

Acid S with a pH of 5.

If you wanted to change the pH of S from 5 to 7, which would be the BEST substance to add?

• Water

• Ethanol

• Ammonia

• Vinegar

The actual change which occurs when aqueous hydrochloric acid and aqueous sodium hydroxide react is

• H⁺ (aq) + OH^- (aq) --> H₂O (aq)

• Na⁺ (aq) + Cl^- (aq) --> NaCl (aq)

• HCl (aq) + NaOH (aq) --> NaCl (s) + H₂O(l)

• HCl₂(aq) + NaOH (aq) --> NaCl₂ (aq) + H₂O (l)