Preparation of Salts (C7.3)

Front

How is a soluble salt made?

Back

By the reaction of an acid with an insoluble base

Answer explanation

A soluble salt is formed when an acid reacts with an insoluble base, resulting in a chemical reaction that produces the salt and water. This process is known as neutralization.

Front

Why is the insoluble base added in excess during the preparation of a soluble salt?

Back

To ensure that all of the acid has reacted

Answer explanation

Adding the insoluble base in excess ensures that all of the acid has reacted, as any unreacted acid will remain in solution. This guarantees complete neutralization, leading to the formation of the soluble salt.

Front

What step is taken to remove the excess insoluble base after the reaction?

Back

Filtration

Answer explanation

Filtration is the correct step to remove excess insoluble base after the reaction, as it separates solid particles from the liquid, allowing the soluble components to pass through while retaining the insoluble base.

Front

What is left in the solution after the excess base is removed?

Back

Only the salt and water

Answer explanation

After removing the excess base, the reaction between the acid and base produces a salt and water. Therefore, what remains in the solution is only the salt and water.

Front

What is the balanced symbol equation for the preparation of copper(II) sulfate from copper(II) oxide?

Back

CuO + H2SO4 → CuSO4 + H2O

Answer explanation

The correct equation is CuO + H2SO4 → CuSO4 + H2O, as it shows the reaction of copper(II) oxide with sulfuric acid to produce copper(II) sulfate and water, which is the desired preparation method.

Front

Insoluble base

Back

A base that does not dissolve in water

Answer explanation

An insoluble base is defined as a base that does not dissolve in water. This distinguishes it from soluble bases, which do dissolve. Therefore, the correct choice is 'A base that does not dissolve in water'.

Front

How are crystals produced from a salt solution?

Back

By heating the solution and then cooling

Answer explanation

Crystals are produced from a salt solution by heating it to dissolve more salt, then cooling it to allow the salt to crystallize as the solubility decreases. This method effectively promotes crystal formation.

Front

What method is used to prepare a soluble salt from an acid and alkali?

Back

Titration

Answer explanation

Titration is the method used to prepare a soluble salt from an acid and alkali by carefully adding one solution to another until the reaction reaches neutralization, allowing for precise measurement of reactants.

Front

What piece of equipment is used to measure a fixed volume of acid during titration?

Back

Pipette

Answer explanation

A pipette is specifically designed to measure and transfer a fixed volume of liquid accurately, making it the ideal choice for measuring acid during titration. Other options like beakers and graduated cylinders are less precise.

Front

Why is an indicator used during the preparation of a soluble salt by titration?

Back

To indicate when neutralization has occurred

Answer explanation

An indicator is used to indicate when neutralization has occurred by changing color at the endpoint of the titration, signaling that the acid has completely reacted with the base.