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Alkene and Bromine Water Experiment

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frog1944:
Hi,

For this experiment "identify data, plan and perform a first-hand investigation to compare the reactivities of appropriate alkenes with the corresponding alkanes in bromine water", for my method can I say I used ethane and ethene, but instead of "pouring it in" I bubbled the 2 gases into their corresponding test tubes?
Or is such a method unsuitable for the HSC?

Thanks

MisterNeo:

--- Quote from: frog1944 on May 13, 2017, 05:41:21 pm ---Hi,

For this experiment "identify data, plan and perform a first-hand investigation to compare the reactivities of appropriate alkenes with the corresponding alkanes in bromine water", for my method can I say I used ethane and ethene, but instead of "pouring it in" I bubbled the 2 gases into their corresponding test tubes?
Or is such a method unsuitable for the HSC?

Thanks

--- End quote ---

Hi, I would recommend the normal cyclohexane and cyclohexene experiment because most schools use that method since it is simpler than bubbling.
It is also hazardous using ethane and ethene gas because ethane does not react and will fill up the laboratory unless done under a fume hood. Same with ethene as not all of it will react and can escape. They are also flammable gases.
HSC markers will likely be confused when everyone uses the cycloalkane/ene method and they see an outlier that says ethane.

Hope this helps, I would use the cyclohexane since it is commonly taught. :)

frog1944:
Yeah that make sense. Thank you very much.

Should we know the reaction between cyclohexane and bromine water in the presence of UV light? I've seen that question asked before in a trial exam, but I haven't seen it in a HSC exam (as far as I've currently looked).

RuiAce:

--- Quote from: frog1944 on May 27, 2017, 08:03:10 am ---Yeah that make sense. Thank you very much.

Should we know the reaction between cyclohexane and bromine water in the presence of UV light? I've seen that question asked before in a trial exam, but I haven't seen it in a HSC exam (as far as I've currently looked).

--- End quote ---
There's no excuse for you to not know it. The band 6 student prepares for every possibility for the exam, including this one.

Additionally, the band 6 students always gets the high marks because he/she remembers to actually put in these equations when describing practicals etc. It shows a more proficient level of understanding.

frog1944:
Ok, thanks.
How do I know to what extent my knowledge should be? Before doing those trial questions I hadn't seen any thing on the reaction, especially as the dot points don't seem to directly address it.

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