INTEC Chemistry Blog

CHM456 – Syllabus and Lab practicals

Posted on: September 10, 2012

A) SyllabusSyllabus-CHM456-Students-copy
The syllabus is a very useful document which lists (albeit in general terms) what topics you must know for the exam. You can use it to help with effective revision strategies.

B) Lab practicals: CHM456 LABORATORY-Students-copy
Note: You must read the relevant practical in advance of attending the lab session. Indeed, the lab manual states the following:

Laboratory Note Book/Jotter

Do not come into a laboratory unprepared. Read and understand the experiments ahead of time; no more reading should be done during lab session. If you do not do this, you will be unable to plan and use your time efficiently. There are several lab techniques that you need to read on your own for each lab session for example distillation, extraction, crystallization etc. They are self-explanatory and if you are unclear about something always consult the lecturer. Students must write/draw a brief outline/flowchart of the procedure of the experiment before coming to the lab. Your note book will be checked by your lecturer for assessment.

In addition, you often have to do some work/calculations/data look-up BEFORE you enter the lab. You MUST make sure you do this.

And of course, the usual warnings of safety in the lab apply.

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4 Responses to "CHM456 – Syllabus and Lab practicals"

Salam Sir. i would to ask u a question. in the preparation of 4-methylcyclohexene experiment, when we were doing the distillation, we know that the boiling point of cyclohexene is lower than phosphoric acid. but how can a small amount of phosphoric acid evaporated and appeared in the receiving flask?

Salam.

The phosphoric acid used was 85% yes? According to http://jack.ecosse.org/design/98-9/design98/data/phos-acid/phos-acid-phyprop.html, 85% H3PO4 has a vapour pressure at around 100oC of 14.8 KPa. (strangely another source, http://www.innophos.com/__sitedocs/innophos-phosphoric-acid-table-3456.pdf, puts this much higher at 111.0).

This means that some H3PO4 vaporises in the reaction, much like water left in a beaker will eventually evaporate even though it’s not being boiled.

So some H3PO4 vapor comes through with the boiling 4-methylcyclohexene. Some water also comes off.

The only difference is the gaseous alkene and gaseous water came off by having being boiled, but the H3PO4 comes off before boiling occurs via vaporisation.

Does that answer your question?

yeap! so the presence of the H3PO4 in the receiving flask is caused by the vaporisation before boiling occurs. thank you Sir.

Good.

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