Core Practical 12 Lab

Prepare a transition metal complex

Aim

To prepare a transition metal complex

These videos & activities will support your laboratory work and help you with the analysis of your results

Equipment

● copper(II) sulfate ● 10 cm3 ethanol ● 2 cm3 concentrated ammonia solution ● crushed ice ● Bϋchner flask and funnel and vacuum filtration apparatus ● filter paper ● 1 pair of gloves ● 1 test tube ● one 50 cm3 beaker ● one 100 cm3 beaker ● one 10 cm3 graduated pipette ● 1 pipette filler ● 1 spatula ● 1 stirring rod ● mass balance (2 d.p.) and weighing boat ● access to a kettle

Things to consider CPAC 1a

Correctly follows instructions to carry out the experimental techniques or procedures.

· Follows step-by-step instructions correctly & with little/no intervention

Things to consider CPAC 2b

CPAC 2b - Carries out techniques or procedures methodically, in sequence and in combination, identifying practical issues and making adjustments when necessary

· Use balance skilfully to accurately weigh (to 2 dps) the copper sulphate

· Use volumetric pipette skilfully to accurately add the 4cm³ of water

· Safe and appropriate addition of ammonia (fume cupboard; gloves; plastic pipette)

· Carry out the washings in a Büchner funnel as per instructions with no/little prompting

· Use balance skilfully to accurately weigh (to 2 dps) the final, dry crystals

· Any practical issues are identified and adjustments made if necessary

Procedure

1. Crush the iron tablets using the pestle and mortar.

2. Transfer the crushed tablets to a weighing boat and measure their combined mass. Record this mass.

3. Empty the crushed tablets into the small beaker and reweigh the weighing boat. Record this mass.

4. Add 100 cm3 1.5 mol dm−3 of sulfuric acid to the small beaker. Stir to dissolve as much of the tablets as possible.

5. Filter the solution (to remove any undissolved solids) into the volumetric flask. Rinse the beaker with more sulfuric acid and add the washings to the volumetric flask. Make up to the mark with distilled/deionised water. Stopper and shake.

6. Pipette 25.0 cm3 of this solution into the conical flask.

7. Titrate the iron(II) solution with potassium manganate(VII) solution until the mixture has just turned pink. On standing, the pink colour will disappear because there is a secondary reaction between the KMnO4 and another ingredient in the tablet. Do not add any more KMnO4.

8. Record your results in an appropriate format.

9. Repeat the titration until concordant results are obtained.

Things to consider CPAC 3b

CPAC 3b - Uses appropriate safety equipment and approaches to minimise risks with minimal prompting.

· Collect all eqpt at start to minimise walking around the lab once practical work

· Set up work space in an organised fashion

· Keep work space tidy and organised

· Wear safety goggles, lab coat, throughout

· No spillages/deals with spillages appropriately with minimal fuss

· Keep stoppers on bottles when not in use

· No / minimal prompts required re safe working

· No / minimal prompts required re safe use of equipment and chemicals

· Correct disposal of reaction mixture (reagents & products) at end of practical

· Area cleared away properly & cleaned down (if needed) for following students without prompting

Things to consider CPAC 4a

CPAC 4a – Makes accurate observations relevant to the experimental or investigative procedure.

· Write down the exact burette value to 0.05cm³

· Measure masses to at least 2dp’s

· Read scales correctly on all pieces of apparatus

· Read from bottom of meniscus when using burette

Understanding How to Stay Safe

Hazcards COSHH

Read the Hazcards COSHH information for the chemicals used in the practical so that you are aware of how to keep yourself and others safe 27C, 40A, 6.

Wear a lab coat and use eye protection.
Tie long hair back.
Concentrated ammonia solution is corrosive and dangerous to the environment. It must be kept in the fume cupboard and handled wearing gloves.
Copper salts are harmful and dangerous to the environment.
Ethanol is flammable and must be kept away from flames.

Required Resources

Core Practical 12 - Student Sheet.docx

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Consult CLEAPSS Hazcards® 27C, 40A, 6. Perform a risk assessment using up-to-date information before this practical is carried out

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