SCHOOL of CHEMISTRY and Physics

SCHOOL OF CHEMISTRY and Physics

HOWARD COLLEGE CAMPUS

UNIVERSITY OF KWAZULU-NATAL

I, the undersigned (please print your full name):

______

Student No.: ______

do hereby acknowledge having read and understood the documents headed “Occupational Health and Safety” and “Laboratory Rules and Regulations”. Furthermore, I accept that contravention of these rules and regulations may lead to my expulsion from the laboratory class, or classes, with subsequent loss of my Duly Performed (DP) certificate.

I agree to abide by any additional laboratory regulations or safety rules presented in writing in this laboratory manual or issued verbally by the lecturer-in-charge, or other responsible member of staff, during pre-laboratory lectures or in the laboratory.

In addition, I understand that I must attend at least 80% of the scheduled laboratory classes and that failure to do so, irrespective of the reasons, may result in the loss of my DP certificate.

DATE: ______

SIGNATURE: ______

It is a legal requirement that

SAFETY GLASSES, LABORATORY COATS AND CLOSED SHOES

are worn in this room at ALL times.

·  Sunglasses (normal or prescription) are NOT to be worn as a substitute for safety glasses.

·  Prescription glasses (except sunglasses) are acceptable PROVIDED THEY COVER THE EYES COMPLETELY.

·  Some types of contact lens should not be worn in the laboratory. Check with your lens supplier.

·  All shoes MUST be closed. No high heels are allowed.

·  All headgear such as hats and scarves must be made safe. Long hair MUST be tied back.

General Fire Orders

Fire-fighting instructions are exhibited in each laboratory, but the following orders must always be obeyed.

In the event of a fire

Attack it at once using the appropriate fire-fighting equipment and SHOUT for help.

On hearing a fire evacuation alarm

Stop normal work immediately.

Make safe any apparatus and material in use, shutting off any local gas taps/valves, electricity and other potentially dangerous services under your control.

Immediately leave the building.

Go to the Fire Evacuation Area outside the main entrance to the building; unless you have been given any other instructions.

Occupational Health and Safety (OHS)

YOU are warned that all substances handled and all operations performed in a laboratory can be hazardous or potentially hazardous. All substances must be handled with care and disposed of according to laid down procedures. All operations and manipulations must be carried out in an organized and attentive manner.

In order to assist you in developing good and safe laboratory techniques, a set of Laboratory Rules and Regulations is attached. You are required to read these and acknowledge that you have read and understood them. Additionally, in the laboratory manuals and/or pre-practical lectures your attention will be drawn to the correct and safe handling of specific chemicals/reagents/solvents, and to the correct/safe manner in which specified laboratory operations must be carried out. These specific instructions and/or warnings must never be ignored.

Laboratory Rules and Regulations

·  Students must be present before the start of each scheduled practical session. Latecomers will be refused entry to the laboratory.

·  No student will be permitted to work in the laboratory outside of practical hours.

·  Do not put anything into your mouth while working in the laboratory. NEVER taste a chemical or solution. Eating and drinking is PROHIBITED in all laboratories.

·  All students are required to wear a laboratory coat. No student will be permitted to work in a laboratory without one.

·  All students who do not wear conventional spectacles must wear eye protection. These must be worn throughout all practical sessions

·  All students must wear closed shoes while in the laboratory.

·  All students must have a laboratory towel to dry apparatus and clean bench-tops.

·  No entry is allowed into preparation and issue rooms.

·  Apparatus and chemicals are not to be removed from the laboratory.

·  Students will find the laboratory benches clean on arrival in the laboratory. The bench at which you work must be left clean when you leave the laboratory at the end of the practical session. Bench tops must be wiped clean. Glassware and other apparatus should be left clean and dry, unless otherwise indicated or instructed. Sinks and basins must be cleaned after each practical.

·  Work areas must at all times be kept clean and free from chemicals and apparatus that are not required. All glassware and equipment must be returned to its proper place, clean and dry and in working condition, unless otherwise indicated or instructed.

·  All solids must be discarded into the bins provided in the laboratory. Never throw matches, paper, or any insoluble chemicals into the sinks. Solutions and chemicals that are emptied into sinks must be washed down with water to avoid corrosion of the plumbing. Waste solvents must be placed into the special waste solvent bottles provided.

·  Before leaving the laboratory at the end of the practical session, make sure that all electrical equipment is switched off, and that all gas and water taps are shut off.

·  Students who break or lose equipment allocated to them will be required to pay for replacements. All breakages or losses must be reported to the technician in charge.

·  Do NOT heat graduated cylinders or bottles.

·  Any apparatus or glassware, which has to be heated, must be heated gently at first, with heating gradually increased thereafter.

·  Balances must be treated with care and kept clean and tidy at all times.

·  Fume-hoods must be used when handling toxic and fuming chemicals. Other operations, such as ignitions, are also carried out in fume-hoods. The only parts of the body that should ever be in the fume-hood are the hands - never put your head inside a fume-hood!

·  Never leave a laboratory experiment unattended!!

·  Reagent bottles must be re-stoppered immediately after use. It is ABSOLUTELY FORBIDDEN to introduce anything into reagent bottles - not even Pasteur pipettes! Solutions and reagents taken from bottles must NEVER be returned to the bottles. Do not place the stopper of a reagent bottle onto an unprotected bench top.

·  Laboratory reagents and chemicals must be returned to their correct places immediately after use. Spillage must be cleaned off bottles/containers.

·  Liquids - whether corrosive or not - must be handled with care and spillage on the bench or floor should be avoided. Any spillage should be cleaned up at once. If the liquid is corrosive (acids or bases), call your demonstrator or staff member in charge. Never hold a container above eye level when pouring a liquid.

·  When carrying out a reaction, or boiling a liquid in a test tube, point the mouth of the test tube away from yourself and others in the laboratory.

·  Beware of hot glass and metal. Never handle any item that has been in a flame, hot oven, or a furnace without taking precautions. Use leather/asbestos gloves/tongs, or ask for advice.

·  Report all accidents, cuts, burns, etc., HOWEVER MINOR, to your demonstrator or the staff member in charge. Eyewash stations are located in various places in the laboratory. Ensure that you know where the nearest one to your bench is located.

·  A chemical laboratory is not a place for horseplay. Do not attempt any unauthorised experiments. Do not play practical jokes on your classmates - transgressors will be banned from the laboratory, with consequent refusal of a Duly Performed (DP) Certificate.

Instructions to Students

Read the following instructions CAREFULLY. Make sure you understand the instructions and sign the declaration at the front of the manual.

·  Fire Extinguishers are provided in the laboratory. Make sure you know where they are situated and how to use them. N.B. A SHOWER is situated in front of the lecturer's desk, as well as in the corridor outside. Make sure you know where they are!

·  Gas is highly flammable. It can form dangerous explosive mixtures with air when not controlled. GAS TAPS MUST BE TURNED OFF WHEN GAS IS NOT IN USE. Slow leaks can lead to dangerous concentrations.

·  Burners: Students must provide their own matches or lighters. The use of paper spills is FORBIDDEN as it poses a fire hazard.

·  Flammable solvents such as ether, alcohol, hexane, benzene, acetone, etc. are used in the organic laboratory. Students must take care when handling these solvents. The following rules are important:

·  Inflammable solvents are NOT TO BE HEATED IN OPEN CONTAINERS over a flame. These should be heated over a steam bath or under reflux conditions.

·  Solvents, such as chloroform, hexane, ether, which are immiscible with water must be disposed of by carefully pouring them into the WASTE SOLVENT bottles located in the fume cupboards. They may NOT be poured down sinks or troughs.

·  Solvents that are miscible with water (e.g..alcohol and acetone) may be poured into the sinks, provided they are washed away with an ample volume of water.

·  Glassware with ground glass joints is expensive and must be treated with care. After use, glassware must be carefully cleaned, dried, and ground surfaces must be lightly smeared with petroleum jelly. This prevents the "freezing together" of the joints. The process of "freezing" is accelerated by the presence of any alkaline solid or solution left on the surfaces. The joints should NEVER be forced or heated with a flame. Disassemble ALL joints before leaving the laboratory.

·  Students must be careful when using balances. ALL SPILLAGES MUST BE CLEANED UP and balances must be left clean.

·  Laboratory benches must be looked after. Acid spillages must be neutralised with sodium bicarbonate and cleaned up immediately. Bunsen burners, hot glassware and steam baths must be placed on asbestos mats.

·  Refuse Bins are for SOLIDS only. No burning or smoldering materials may be placed in bins.

·  Sinks and troughs are for liquids only. Solid material will cause blockage of the drainage system.

·  Use of Fume Cupboards: The careless use of certain chemicals makes working in the laboratory extremely unpleasant. Brominations must be done in the fume cupboard. Always check warnings on the reagent bottles BEFORE using.

·  Practical Preparation: Before the practical class you are required to:

·  Familiarize yourself with the experimental procedures you are about to perform.

·  Read up the relevant section in your textbook.

·  Fill in specific information, as requested.

·  Reactions will be discussed in lectures, practical work being examinable in your examination.

·  All SOLID products prepared and derivatives of unknowns must be submitted in neatly labeled sample tubes. Liquid products may not be handed in, but must be shown to your demonstrator for verification and then poured into the appropriate bottle on the demonstration bench.

Report sheets for a particular practical MUST be handed in at the conclusion of that practical session. They will then be marked and returned to you at the start of the following laboratory.

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Schedule of Practical Work

Page No

Practical 1A Preparation of the “double salt”

Ammonium copper sulphate 11

Practical 1B Preparation of the “coordination complex”

tetraamine- copper(II) sulphate 11

Practical 2 Preparation of [Co(NO2)6]3- 12

Practical 3 Preparation of [Co(acac)3] 13

Practical 4 Preparation of copper(I) chloride 14

Practical 5 Preparation of chromium metal by the

Thermite Reaction 15

Practical 6 Construction of model crystals 16

Preparation of the “double salt” ammonium copper

sulphate

Procedure

Dissolve copper(II) sulphate pentahydrate (2 g) and ammonium sulphate (1 g) in hot water (5 mL). Cool the solution, and filter the crystals at the pump. Dry between pads of filter papers. Evaporate the filtrate to about 5 mL, cool, filter, and dry the second crop of crystals. Record the total weight of product but keep the two samples separate. Calculate the percentage yield.

Preparation of the “coordination complex”

tetraamine- copper(II) sulphate

CuSO4 + 4NH3 ® [Cu(NH3)4]SO4.H2O

Procedure:

Dissolve four grams (4 g) of copper(II) sulphate pentahydrate in a mixture of 6 mL of concentrated ammonia and of 4 mL water. Cool the resulting deep-blue solution in ice, stirring continuously while 15 mL of alcohol is added drop-wise using a dropper. Allow the mixture to stand in the cold for at least 4 hours, preferably overnight; the supernatant liquid should be almost colourless. Filter the crystalline product, wash first with 10 mL of a cold equal volume mixture of alcohol and concentrated aqueous ammonia, and then with 10 mL each of 95% alcohol and ether. Dry the salt in air and calculate the percentage yield.

Preparation of [Co(NO2)6]3-

Co(NO3)2 + 5NaNO2 + NO2− ® Na3[Co(NO2)6] + 2NaNO3

Procedure:

12 g of pure potassium-free sodium nitrite are dissolved in 12 mL of hot water. The solution is cooled to 50°C, and 4 g of cobalt nitrate hexahydrate are dissolved in the liquid. With continuous stirring, 4 mL of 50% acetic acid are added dropwise from a burette and the dark brown solution is transferred to a filter flask fitted with a stopper and an inlet tube leading almost to the bottom of the vessel. A steady stream of air is drawn through the solution for 30 minutes to remove excess oxides of nitrogen; some product may crystallize out during the aeration. The liquid and any solid that has formed (the more vigorous the air current the more material tends to settle out) are now placed in a beaker and surrounded by an ice bath. Add 20 – 30 mL of 95% alcohol slowly with agitation, and the mixture is then allowed to crystallize in the cold for 30 minutes. The orange-brown product is filtered by suction and the mother liquor is set aside. The material is washed three times with 10 mL of alcohol; the final washing should be almost colourless. The crystals are dried in air. Calculate the percentage yield.

Preparation of [Co(acac)3]

Procedure:

Slurry 2.5 g powdered cobalt(II) carbonate and 20 mL acetylacetone in a 125 mL Erlenmeyer flask. Heat the mixture to 100°C on a steam bath. Transfer the flask immediately onto a white tile and add 15 mL of 10% H2O2 at a rate of to 2 mL/min while stirring. Reheat the reaction mixture to incipient boiling, then add 15 mL more of H2O2 as before. After addition is complete, heat to boiling.

Cool the mixture in an ice-salt bath for half an hour and filter the green-black sludge with suction. Wash with water followed by small (3 x 5 mL) amounts of cold ethanol. The yield should be about 6 g of raw product. Recrystallize from toluene. If any of the raw product cannot be dissolved in hot toluene, filter the hot solution by gravity to eliminate the insoluble impurities. Dry at 110°C. The yield of purified dark green crystals is expected to be 4.0 to 4.5 g pure. Calculate the percent yield.