INTEC Chemistry Blog

CHM412 CHM456 CHM556 LAB REPORTS and stuff.

Posted on: October 2, 2013

Please do the following:

Use the cover sheet provided HERE. Obviously fill it in (handwriting OK) accordingly.

  • No need to write introduction IF already given to you (in the lab manual/sheet).
  • No need to write theory IF already given to you in the lab manual/sheet.
  • No need to write the procedure/method IF what you did was the same as the procedure you were given in the lab sheet/manual.
    But
    If you did something different or extra then write down what you did.E.g. “Two distinct layers were slow to form in the separating funnel, so more volatile solvent was added and conc NaCl solution was added to the water layer.”E.g. “When drying the organic layer the solvent evaporated  so couldn’t be filtered, hence an extra 30ml of the solvent was added to the Na2SO4 drying agent.”E.g. “The final product was so small and unmanageable (a fine coating on the glass) that the whole experiment was repeated but using twice the amount of reactants in the beginning.”

    etc….

You can therefore write in your report:
Theory: as in CHMxyz Experiment pqr lab manual
Procedure/Me thod: as in lab manual – no alterations made. [If in fact you did not make any alterations]

I am interested in OBSERVATIONS and RESULTS and what CONCLUSIONS you can make from the results.

E.g. of Observations: Small bubbles of an unknown identity were were seen even after the recommended time to complete the reaction had passed.

etc.

When reporting chemical test observations state what you have in the beginning AND at the end.
E.g. Uknown colourless liquid added to purple coloured KMnO4 solution. The MnO4- solution decolourised and black solids were seen.

Results & calculations:

Make sure you PRESENT THE RESULTS CLEARLY.  Describe clearly what some value is.

E.g.
Approximate melting point range  [Fast heating] = 130oC(started melting) – 134oC (finished melting)
Accurate melting point range  [slow heating] = 129oC(started melting) – 130oC (finished melting)

mass of filter paper (a) = 1.7434g
mass of watchglass (b) = 43.3450g
mass of  mass of filter paper, watchglass and compound (c) = 46.2221g [oven dried]
so mass of compound = c -(a+b) = 46.2221 – (1.7434 + 43.3450) = 1.1337 g

Molar mass of studophene (e) = 236 g/mol
density of studophene (f) = 0.942 g/ml
Volume of studophene used (g) = 15.0 ml
so mass of studophene used (h)= f x g =  0.942 x 15.0 = 14.13g
so moles of studophene (i) = h / e =  0.0599 moles

etc…

Results MUST be signed by me (or my assistant if I have one), and you must submit the original signed results with your report. Students should submit separate reports that have not been copied, you MUST submit original work.

Conclusions:  In the conclusions you NEED TO COMMENT ON YOUR RESULTS.

E.g. The % yield should not have been greater than 100%. Out value of 320% could have been due to liquid impurities in teh liquid product, and was perhaps the silvent used. The NMR spectrum of the compound confirms the presence of the imputiry.

E.g. The theoretical melting point of 133oC is 4 oC higher than the value from experiment, suggesting the experimental sample is not pure as impurities depress melting point. [mpt source: Chempedia URL]

E.g. The synthesis of studophene from studanol takes place in high yields of 80%

Conclusions can also propose improvements on the experiment, but generally the procedures are well known and work.

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