Chapter 8 Acids and Bases 8.2 Properties of Bases and Alkalis

Which substance is a base?

• copper(II) sulfate

• iron(II) oxide

• sulfur dioxide

• ethanoate

Which substance is a base?

• ammonium chloride

• barium hydroxide

• silicon dioxide

• potassium nitrate

What substance must be formed when an acid reacts with a base?

• salt and water
• carbon dioxide and water
• hydrogen and salt

• salt and carbon dioxide

Which substance is an alkali?

• copper(II) hydroxide

• calcium hydroxide

• phosphorus (V) oxide

• sulfur dioxide

Which substance is an alkali?

• ammonium chloride

• ammonia solution

• magnesium hydroxide

• zinc hydroxide

When barium hydroxide solution is warmed with ammonium carbonate,

• barium and water are formed

• barium carbonate and ammonia are formed

• barium carbonate and water are formed

• barium carbonate, ammonia and water are formed

What will be observed* when an alkali is heated with an ammonium salt?

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Answer explanation

A colourless gas with pungent smell is evolved.

A colorless gas is evolved when an alkali is heated with an ammonium salt but Effervescence is not observed when this reaction takes place. Explain why.

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Answer explanation

Ammonia gas is soluble in water. Thus ammonia gas produced in the reaction dissolves in the aqueous solution of the reaction mixture.

Reactions of alkalis with ammonium salts produce ammonia gas. How do we prove that ammonia gas is produced

• Insert a lighted splint and lighted splint extinguished with a 'pop' sound.

• bubble the gas into limewater and white precipitate formed in limewater.

• used a moist red litmus paper which will turn blue.

• used a moist blue litmus paper which will turn red.

An excess of acid in the stomach causes indigestion that can be cured by an anti-indigestion tablet. What could the tablet contain to reduce the acidity?

• dilute nitric acid

• magnesium hydroxide

• sodium chloride

• Universal indicator