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Author Topic: chem paper 1 doubt  (Read 3229 times)

Offline zbzbzb25

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chem paper 1 doubt
« on: May 20, 2009, 12:58:57 pm »
ASALAMOALAIKUM WARAHMATULLAHI WABARAKATUHU WAMAGHFIRATUHU
n hi!

which apparatus is most suitable for producing ethanol by fermentation?

A- a conical flask with cotton wool at its mouth containing sugar sol and yeast,not being heated
B-a conical flask with a bung containing sugar sol and yeast,being heated
C-a conical flask with sugar sol and yeast, being heated and no cotton wool or bung with steam escaping
D- a conical flask placed in a tray of ice,the conical flask contains sugar sol and yeast (no bung or cottonwool)

this is qn no. 40 from 0620 november 1999

mark scheme says (A)
but i thnk it shud be (B)

Thanks
JAZA KALLAH KHAIR
ALLAH HAFIZ
FIAMANALLAH
Take care
bye
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Q80BOY

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Re: chem paper 1 doubt
« Reply #1 on: May 20, 2009, 01:04:11 pm »
i agree with u, in the revision guide i use, the diagram shows a bung and an air lock

hope i helped  :)

By the way loved the beginning and ending of ur post  ;)
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Offline annie_angel

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Re: chem paper 1 doubt
« Reply #2 on: May 20, 2009, 03:04:25 pm »
i think it actuallly is A as if it is heated da yeast would be killed...and b4 da ethanol is made it would be of no use thn...hope this helps
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Offline annie_angel

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Re: chem paper 1 doubt
« Reply #3 on: May 20, 2009, 03:05:59 pm »
Quote from: Q80BOY on May 20, 2009, 01:04:11 pm
i agree with u, in the revision guide i use, the diagram shows a bung and an air lock

hope i helped  :)

By the way loved the beginning and ending of ur post  ;)
bung and an airlock IS needed but if da thing is heated the yeast would die...
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Q80BOY

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Re: chem paper 1 doubt
« Reply #4 on: May 20, 2009, 03:07:09 pm »
Quote from: annie_angel on May 20, 2009, 03:05:59 pm
Quote from: Q80BOY on May 20, 2009, 01:04:11 pm
i agree with u, in the revision guide i use, the diagram shows a bung and an air lock

hope i helped  :)

By the way loved the beginning and ending of ur post  ;)
bung and an airlock IS needed but if da thing is heated the yeast would die...

ya, so its not A, cause A says that cotton wool is used  :-\
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Offline annie_angel

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Re: chem paper 1 doubt
« Reply #5 on: May 20, 2009, 03:07:59 pm »
the co2 escapes...
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Q80BOY

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Re: chem paper 1 doubt
« Reply #6 on: May 20, 2009, 03:09:41 pm »
Quote from: annie_angel on May 20, 2009, 03:07:59 pm
the co2 escapes...

isnt that why we have an airlock ?? for the CO2 to escape?
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Offline annie_angel

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Re: chem paper 1 doubt
« Reply #7 on: May 20, 2009, 03:11:55 pm »
Quote from: Q80BOY on May 20, 2009, 03:09:41 pm
Quote from: annie_angel on May 20, 2009, 03:07:59 pm
the co2 escapes...

isnt that why we have an airlock ?? for the CO2 to escape?

air LOCK is dere so oxygen doesnt anter or else ethanol would oxidise....or we would get sumthing else [ethanoic acid i think]
 but not ethanol
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Offline annie_angel

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Re: chem paper 1 doubt
« Reply #8 on: May 20, 2009, 03:14:13 pm »
Quote from: annie_angel on May 20, 2009, 03:11:55 pm
Quote from: Q80BOY on May 20, 2009, 03:09:41 pm
Quote from: annie_angel on May 20, 2009, 03:07:59 pm
the co2 escapes...

isnt that why we have an airlock ?? for the CO2 to escape?

air LOCK is dere so oxygen doesnt anter or else ethanol would oxidise....or we would get sumthing else [ethanoic acid i think]
 but not ethanol

enter*
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Q80BOY

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Re: chem paper 1 doubt
« Reply #9 on: May 20, 2009, 03:14:20 pm »
Quote from: annie_angel on May 20, 2009, 03:11:55 pm
Quote from: Q80BOY on May 20, 2009, 03:09:41 pm
Quote from: annie_angel on May 20, 2009, 03:07:59 pm
the co2 escapes...

isnt that why we have an airlock ?? for the CO2 to escape?

air LOCK is dere so oxygen doesnt anter or else ethanol would oxidise....or we would get sumthing else [ethanoic acid i think]
 but not ethanol

The airlock is used to allow CO2 out and prevent O2 and bacteria entering the fermentation jar, thus allowing anaerobic respiartion to occur.

why is the cotton needed? and where is it placed?
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Offline annie_angel

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Re: chem paper 1 doubt
« Reply #10 on: May 20, 2009, 04:07:49 pm »
Quote from: Q80BOY on May 20, 2009, 03:14:20 pm
Quote from: annie_angel on May 20, 2009, 03:11:55 pm
Quote from: Q80BOY on May 20, 2009, 03:09:41 pm
Quote from: annie_angel on May 20, 2009, 03:07:59 pm
the co2 escapes...

isnt that why we have an airlock ?? for the CO2 to escape?

air LOCK is dere so oxygen doesnt anter or else ethanol would oxidise....or we would get sumthing else [ethanoic acid i think]
 but not ethanol


The airlock is used to allow CO2 out and prevent O2 and bacteria entering the fermentation jar, thus allowing anaerobic respiartion to occur.

why is the cotton needed? and where is it placed?

A- a conical flask with cotton wool at its mouth containing sugar sol and yeast,not being heated...it says at its mouth...and i think its used for letting co2 escape
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Offline MaNa

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Re: chem paper 1 doubt
« Reply #11 on: May 20, 2009, 04:08:15 pm »
I guess its B bcuz uu doo need to heat the yeast till
30 degree celcius
bcuz below that its inactive n more then that its destroyed
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Offline annie_angel

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Re: chem paper 1 doubt
« Reply #12 on: May 20, 2009, 04:14:57 pm »
but temperature isnt specified
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Q80BOY

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Re: chem paper 1 doubt
« Reply #13 on: May 20, 2009, 04:18:21 pm »
the question says: which apparatus is most suitable for producing ethanol by fermentation?

my text book and notes say that CO2 escapes from the airlock, no cotton wool is mentioned

are u sure its cotton wool ??  :-\
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Offline MaNa

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Re: chem paper 1 doubt
« Reply #14 on: May 20, 2009, 04:19:32 pm »
yea
which means its room temperature
w8 it should be 18-20 degree
so yea now it make sence why it is A
with heat
bcuz room temperature is 24 degree
n soo it fermentatrion will carry on
 
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