Planning Experiments and Investigations

You are not expected to do any experimental work for this question.

Q is a mixture of solid magnesium oxide and solid barium sulfate.

Magnesium oxide is insoluble in water. It reacts with dilute hydrochloric acid to make a solution of magnesium chloride.

Barium sulfate is insoluble in water and does not react with dilute hydrochloric acid.

Plan an investigation to obtain pure magnesium chloride crystals and pure barium sulfate solid from Q.

Your plan should describe the use of common laboratory apparatus, dilute hydrochloric acid and Q. No other chemicals should be used.

Your plan should include:

• the apparatus needed
• the preparation of magnesium chloride solution
• the method to obtain pure magnesium chloride crystals
• the method to obtain pure barium sulfate solid
• how to test that the barium sulfate is pure.

You may draw a diagram to help answer the question.

You are not expected to do any experimental work for this question.

Q is a mixture of solid copper(II) carbonate and solid lead sulfate.

Lead sulfate is insoluble in water and does not react with dilute sulfuric acid.

Copper(II) carbonate is insoluble in water. It reacts with dilute sulfuric acid to form copper(II) sulfate solution.

Plan an investigation to obtain pure copper(II) sulfate crystals and pure lead sulfate solid from Q.

Your plan should describe the use of common laboratory apparatus, dilute sulfuric acid and Q. No other chemicals should be used.

Your plan should include:

• the apparatus needed
• the preparation of copper(II) sulfate solution
• the method to obtain pure copper(II) sulfate crystals
• the method to obtain pure lead sulfate solid
• how to test that the lead sulfate is pure.

You may draw a diagram to help answer the question.

You are not expected to do any experimental work for this question.

Alcohols are used as fuels to heat water.

Plan an experiment to determine which alcohol, methanol or ethanol, releases more thermal energy per gram of alcohol burned.

Your plan should describe the use of an alcohol burner, as shown in Fig. 3.1, to heat water. You should use water, methanol, ethanol and common laboratory apparatus. No other chemicals should be used.

Your plan should include:

• the additional apparatus needed
• the method to use and the measurements to take
• how the measurements are used to determine which alcohol releases more thermal energy per gram burned.

You may draw a diagram to help answer the question.

You are not expected to do any experimental work for this question

Barium carbonate decomposes when heated. The word equation for the reaction is shown.

$$\text{barium carbonate} \rightarrow \text{barium oxide} + \text{carbon dioxide}$$

Plan an experiment to determine the percentage loss in mass when barium carbonate is heated.

Your plan must include the use of common laboratory apparatus and a sample of barium carbonate. No other chemicals should be used.

Your plan must include:

• the apparatus needed
• the method to use and the measurements to take
• procedures to ensure that the percentage determined is as accurate as possible
• how the measurements are used to determine the percentage loss in mass.

You may draw a diagram to help answer the question.

You are not expected to do any experimental work for this question.

Copper(II) carbonate reacts with dilute sulfuric acid at room temperature.

The word equation for the reaction is shown.

$$\text{copper(II) carbonate} + \text{sulfuric acid} \rightarrow \text{copper(II) sulfate} + \text{carbon dioxide} + \text{water}$$

Plan an experiment to determine the volume of carbon dioxide formed when a known mass of copper(II) carbonate completely reacts with dilute sulfuric acid.

Your plan must include the use of common laboratory apparatus, dilute sulfuric acid and copper(II) carbonate. No other chemicals should be used.

Your plan must include:

• the apparatus needed
• the method to use and the measurements to take
• procedures to ensure that the volume measured is as accurate as possible.

You may draw a diagram to help answer the question.

You are not expected to do any practical work for this question.

Argentan is an alloy containing only zinc, nickel and copper.

Zinc and nickel both react with dilute hydrochloric acid. Copper does not react with dilute hydrochloric acid.

Plan an investigation to find the percentage by mass of copper in a powdered sample of argentan.

Your plan must include the use of common laboratory apparatus, argentan and hydrochloric acid. No other chemicals should be used.

Your plan must include:

• the apparatus needed
• the method to use and the measurements to take
• procedures to ensure that the percentage determined is as accurate as possible
• how the measurements are used to determine the percentage by mass of copper in the sample.

You may draw a diagram to help answer the question.

You are not expected to do any practical work for this question.

Muntz metal is an alloy that contains zinc and copper.

Zinc reacts with dilute sulfuric acid. Copper does not react with dilute sulfuric acid.

Plan an investigation to find the percentage by mass of zinc in a powdered sample of Muntz metal which contains only zinc and copper.

Your plan must include the use of common laboratory apparatus, Muntz metal and sulfuric acid. No other chemicals should be used.

Your plan must include:

• the apparatus needed
• the method to use and the measurements to take
• procedures to ensure that the percentage determined is as accurate as possible
• how the measurements are used to determine the percentage by mass of zinc in the sample of Muntz metal.

You may draw a diagram to help answer the question.

You are not expected to do any experimental work for this question.

Baking powder is used to make cakes rise. When water is added to baking powder, carbon dioxide gas is released.

The longer the baking powder is stored, the less carbon dioxide it releases when water is added.

Plan an investigation to show which of two different samples of baking powder has been stored for longer.

Your plan should include the use of common laboratory apparatus, the two samples of baking powder and water. No other chemicals should be used.

Your plan should include:

• the apparatus needed
• the method to use
• the measurements to take
• the variables to control
• how to use the results to determine which sample has been stored for longer.

You may draw a diagram to help you answer the question.

You are not expected to do any experimental work for this question.

Baking soda is used to make bread rise. When baking soda is heated, it decomposes and carbon dioxide gas is released.

Baking soda also decomposes gradually when it is stored. The longer the baking soda is stored, the less carbon dioxide it releases when it is heated.

Plan an investigation to show which of two different samples of baking soda has been stored for longer.

Your plan should include the use of common laboratory apparatus and the two samples of baking soda. No other chemicals should be used.

Your plan should include:

• the apparatus needed
• the method to use
• the measurements to take
• the variables to control
• how to use the results to determine which sample has been stored for longer.

You may draw a diagram to help you answer the question.

You are not expected to do any experimental work for this question.

Ammonium sulfate is a salt used in fertilisers.

Ammonium sulfate is prepared by neutralising dilute sulfuric acid with aqueous ammonia.

Plan an experiment to prepare pure dry crystals of ammonium sulfate.

Your plan should include the use of:

• common laboratory apparatus
• dilute sulfuric acid
• aqueous ammonia
• methyl orange indicator.

No other chemicals should be used.

Your plan should include:

• the apparatus needed
• the method to use.

You may draw a diagram to help answer the question.