Acids and Alkalis

What is a good definition of acids?

• Substances that generate oxygen ions when dissolved in water.

• Substances that generate hydrogen ions when dissolved in an aqueous solution.

• Substances that generate chlorine ions when dissolved in water.

• Substances that are used in cleaning products.

What can be said about a chemical if it contains hydrogen that can be released as ions in water?

• It is a base.

• It is an alkali.

• It is an acid.

• It is a neutral solution.

What happens when hydrogen chloride – or HCl – is added to water?

• It forms a basic solution.

• It does not react with water.

• It forms hydrogen and chlorine gases.

• It dissolves and the hydrogen and chlorine ions dissociate, forming an acidic solution.

What is the main difference between strong and weak acids?

• Strong acids are less corrosive than weak acids.

• Strong acids completely ionise in water, while weak acids only partially ionise.

• Weak acids produce hydroxide ions in water, while strong acids do not.

• Strong acids can dissolve metals, while weak acids cannot.

Which of the following is an example of a strong acid?

• Ethanoic acid

• Hydrochloric acid

• Water

• Sodium hydroxide

What do alkalis produce when dissolved in water?

• Hydrogen ions

• Chloride ions

• Hydroxide ions

• Carbonate ions

Which of the following is an example of an alkali?

• H₂SO₄

• HNO₃

• NaOH

• HCl

What does the pH scale measure?

• The temperature of a solution

• The acidity or alkalinity of a solution

• The mass of a solution

• The volume of a solution

What is the pH value of a neutral substance?

• 0

• 7

• 14

• 10

On the pH scale, values below 7 indicate what kind of solution?

• Neutral

• Basic

• Acidic

• Pure