Objective I: Acids and Bases - Identify Acids, Bases, Salts

What is the formula of nitric acid?

• HCl

• H₂SO₄

• HNO₃

• H⁺

What is the formula of hydrochloric acid?

• HCl

• H₂SO₄

• HNO₃

• H⁺

Which of the following correctly describes H₂SO₄?

• acid

• base

• salt

Answer explanation

An acid produces H⁺ ions in water.
Hence, it will have the element H in its formula.

Which statements about an acid are correct? Choose 2 answers.

• It must be dissolved in water.

• It contains H⁺ ions.

• It is a metal oxide or metal hydroxide.

• NaCl is an acid.

Answer explanation

When acids dissolve in water, the acid molecules ionise to produce H⁺ ions, giving its acidic properties.

Which of the following statements about a base are not correct?
Choose 2 answers.

• It is a metal oxide.

• It is a metal hydroxide.

• It contains hydrogen ions.

• It is a metal chloride.

Which of the following is a base?
You may choose more than 1 answer.

• KOH

• CuO

• KCl

• CuSO₄

Answer explanation

A base is a metal oxide or metal hydroxide.

What is the formula of magnesium oxide?

• MgO

• Mg₂O

• MgO₂

• Mg₂O₂

What is the formula of potassium hydroxide?

• KOH

• NaOH

• Ca(OH)₂

• NH₃ (aq)

Which of the following is a salt?

• HNO₃

• NaNO₃

• FeO

• Zn(OH)₂

Answer explanation

A salt is formed when the hydrogen ion of an acid is replaced by a metal or ammonium ion.

Which of the following is not a salt?

• K₂SO₄

• Mg(NO₃)₂

• ZnO

• NH₄Cl

Answer explanation

A salt is formed when the hydrogen ion of an acid (e.g. HCl, HNO₃, H₂SO₄) is replaced by a metal or ammonium ion.

ZnO is a base!