Y12 practical exam Q

Which one of the following is a correct procedure for isolating a sample of hydrated copper(II) sulfate from a mixture of hydrated copper(II) sulfate and barium sulfate?

• A. Filter, crystallise filtrate, dry the crystals

• B. Filter, dry the solid on the filter paper

• C. Add water, filter, dry the solid left on the filter paper

• D. Add water, filter, crystallise filtrate, dry the crystals

A student devised an experiment to find the concentration of sulfuric acid in a sample of battery acid.

• A measuring cylinder was used to transfer 10 cm³ of battery acid to a volumetric flask.

• Distilled water was added to the volumetric flask until the volume reached 250 cm³.

• A 25.0 cm³ sample of diluted acid was transferred from the volumetric flask to a conical flask using a pipette.

• A few drops of methyl orange indicator were added to the acid in the conical flask before titrating the acid with NaOH.

Which suggestion would reduce the overall measurement uncertainty in the titration?

• Use less concentrated alkali in the burette.

• Use phenolphthalein indicator instead of methyl orange.

• Use smaller samples of the diluted acid in each titration.

• Begin each titration with the burette filled to the 0.00 cm³ mark.

Which observation would confirm that ammonia gas is released when solid ammonium chloride is warmed with solid calcium hydroxide?

• Damp blue litmus paper turns red when touched onto the solid mixture.

• Damp red litmus paper turns blue when touched onto the solid mixture.

• Damp blue litmus paper turns red when held just above the solid mixture.

• Damp red litmus paper turns blue when held just above the solid mixture.

A student devised an experiment to find the concentration of sulfuric acid in a sample of battery acid.

• A measuring cylinder was used to transfer 10 cm³ of battery acid to a volumetric flask.

• Distilled water was added to the volumetric flask until the volume reached 250 cm³.

• 25.0 cm³ of diluted acid was transferred from the volumetric flask to a conical flask using a pipette.

• A few drops of methyl orange indicator were added to the acid in the conical flask before titrating the acid with NaOH.

• The titration was repeated 5 times but concordant results were not obtained.

Which suggestion would improve the chances of obtaining concordant titres?

• Invert the volumetric flask several times after adding the distilled water.

• Wash the pipette with distilled water between each titration.

• Add extra drops of indicator to the sample when nearing the end point in each titration.

• Use a more concentrated solution of sodium hydroxide in the burette.

A student is provided with 5.00 cm³ of 1.00 mol dm⁻³ ammonia solution. The student was asked to prepare an ammonia solution with a concentration of 0.050 mol dm⁻³. What volume of water should the student add? Tick one box only.

• A. 45.0 cm³

• B. 95.0 cm³

• C. 100 cm³

• D. 995 cm³

A student devised an experiment to find the concentration of sulfuric acid in a sample of battery acid. • A measuring cylinder was used to transfer 10 cm³ of battery acid to a volumetric flask. • Distilled water was added to the volumetric flask until the volume reached 250 cm³. • A 25.0 cm³ sample of diluted acid was transferred from the volumetric flask to a conical flask using a pipette. • A few drops of methyl orange indicator were added to the acid in the conical flask before titrating the acid with sodium hydroxide. • The titration was repeated five times but concordant results were not obtained.

Which colour change is observed at the end point in each titration?

• Yellow to red

• Red to orange

• Yellow to orange

• Red to yellow

A student devised an experiment to find the concentration of sulfuric acid in a sample of battery acid. • A measuring cylinder was used to transfer 10 cm³ of battery acid to a volumetric flask. • Distilled water was added to the volumetric flask until the volume reached 250 cm³. • A 25.0 cm³ sample of diluted acid was transferred from the volumetric flask to a conical flask using a pipette. • A few drops of methyl orange indicator were added to the acid in the conical flask before titrating the acid with NaOH.

Which of these is important in ensuring that the student's experiment is safe?

• Do the titration in a fume cupboard.

• Wear gloves when measuring out the battery acid.

• Wash hands before doing the titration.

• Carry the burette horizontally when collecting the apparatus.

Which diagram shows the correct apparatus for the conversion of hexan-1-ol to hexanal?

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A student devised an experiment to find the concentration of sulfuric acid in a sample of battery acid. • A measuring cylinder was used to transfer 10 cm³ of battery acid to a volumetric flask. • Distilled water was added to the volumetric flask until the volume reached 250 cm³. • A 25.0 cm³ sample of diluted acid was transferred from the volumetric flask to a conical flask using a pipette. • A few drops of methyl orange indicator were added to the acid in the conical flask before titrating the acid with NaOH. • The titration was repeated 5 times but concordant results were not obtained. Which suggestion about rinsing the conical flask between each titration would improve the accuracy of the recorded titres?

• Rinsing with acid.

• Rinsing with alkali.

• Rinsing with water.

• No rinsing with any liquid.

A student completes some test-tube reactions on five solutions, P, Q, R, S and T. The student completes each test on separate samples of each solution. Observations are shown in the table. Which solution contains carbonate ions? Tick one box only.

• Solution P

• Solution Q

• Solution R

• Solution S