(Original post by KateSW)
Okay here are some test qs for you guys to answer!
-Define the enthalpy of combustion
-What happens to a Boltzmann Distribution diagram with increased temp?
-What does the molecular ion show in mass spec?
1- Enthalpy change of combustion is the enthalphy change that occurs when one mol of a given substance reacts completely with oxygen under standard conditions (101kPa/1 atmosphere and 298K) with all products and reactants in their standard states.
2- The peak lowers, and the curve flattens giving more molecules with energy above that of the activation energy.
3- The molecular ion in mass spec shows the Mr of the compound/molecule. So allows you to work out the molecular formula once you've found the empirical formula, and it also allows you to work out fragment ions (which remember always have a + charge!)
Here's one for you:
How are scientists trying to reduce the effect of global warming?
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OCR AS - Chemistry Unit F322 - Chains, energy and resource - REVISION! watch
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- 22-05-2011 12:02
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- 22-05-2011 12:03
(Original post by KateSW)
Okay here are some test qs for you guys to answer!
-Define the enthalpy of combustion
-What happens to a Boltzmann Distribution diagram with increased temp?
-What does the molecular ion show in mass spec?
molecular ion peak relative atomic mass -
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- 22-05-2011 12:15
(Original post by Dave_Beeston)
1- Enthalpy change of combustion is the enthalphy change that occurs when one mol of a given substance reacts completely with oxygen under standard conditions (101kPa/1 atmosphere and 298K) with all products and reactants in their standard states.
2- The peak lowers, and the curve flattens giving more molecules with energy above that of the activation energy.
3- The molecular ion in mass spec shows the Mr of the compound/molecule. So allows you to work out the molecular formula once you've found the empirical formula, and it also allows you to work out fragment ions (which remember always have a + charge!)
Here's one for you:
How are scientists trying to reduce the effect of global warming? -
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- 22-05-2011 12:18
will sorting and recycling and incineration for energy count???
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- 22-05-2011 12:20
(Original post by Dave_Beeston)
Here's one for you:
How are scientists trying to reduce the effect of global warming?
EDIT: sorry I was a bit too late!!
How do catalytic converters work, including an overall equation? -
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Hey guys what do you think the level of difficulty for this paper will be like....I've got predominantly A's in most practice papers but there have been one or two exceptions like the Jan 2010 and Jan 2011 paper in which I got solid B's....so do you think this paper will be a fairly standard paper based on previous years?
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- 22-05-2011 12:25
(Original post by asif123)
Hey guys what do you think the level of difficulty for this paper will be like....I've got predominantly A's in most practice papers but there have been one or two exceptions like the Jan 2010 and Jan 2011 paper in which I got solid B's....so do you think this paper will be a fairly standard paper based on previous years? -
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- 22-05-2011 12:30
anyone else resitting F321 monday??
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- 22-05-2011 12:33
(Original post by shyro1000)
anyone else resitting F321 monday?? -
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- 22-05-2011 12:36
(Original post by kingam)
ME lol got b first time round wbu -
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- 22-05-2011 12:52
(Original post by shyro1000)
no lol i got a U, did shocking, even though i got A's and B's in the mock, i was so devastated. what are you focusing on? -
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- 22-05-2011 12:54
(Original post by KateSW)
How do catalytic converters work, including an overall equation?
2CO +2NO -> N2 + 2CO2
The molecules of nitrogen and carbon dioxide are desorbed into the atmosphere.
How are scientists trying to deal with polymers and CFCs? -
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- 22-05-2011 12:57
(Original post by kingam)
just past papers -
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- 22-05-2011 13:04
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- 22-05-2011 13:12
CFC's are being reduced (due to the Montreal protocol) and replaced by HFC's (which are much much slower at depleting the ozone)
did I miss anything?
What are the pros and cons of steam hydration over fermentation to produce ethanol? -
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- 22-05-2011 13:21
(Original post by KateSW)
What are the pros and cons of steam hydration over fermentation to produce ethanol?
Advantages: the raw material is renewable, does not require oxygen, enzymes can be reused.
Disadvantages: slow process, too much heat can cause enzyme to denature
HYDRATION:
Disadvantages: non-renewable raw material (crude oil), requires oxygen (steam)
advantages: fast processLast edited by shyro1000; 22-05-2011 at 13:25. -
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- 22-05-2011 14:27
i was 1 mark of an A but my course is high so i didnt bother re sitting it because i only need alow B in f322 for an A overall wbu??
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- 22-05-2011 14:29
(Original post by akydon619)
i was 1 mark of an A but my course is high so i didnt bother re sitting it because i only need alow B in f322 for an A overall wbu?? -
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- 22-05-2011 14:39
(Original post by shyro1000)
FERMENTATION:
Advantages: the raw material is renewable, does not require oxygen, enzymes can be reused.
Disadvantages: slow process, too much heat can cause enzyme to denature
HYDRATION:
Disadvantages: non-renewable raw material (crude oil), requires oxygen (steam)
advantages: fast process
May also be worth noting that another disadvantage of fermentation is that the enzyme ceases to function when the concentration (toxicity) of the ethanol is above 14/15%.
I don't understand how the lack of oxygen is an advantage. Since fermentation is anaerobic, it is NECESSARY that there is an absence of oxygen, therefore money will need to be spent on suitable airtight apparatus. Otherwise, ethanol is oxidised to the aldehyde ethanal and then to the carboxylic acid, ethanoic acid. These undesirable compounds affect the flavour of the product. -
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- 22-05-2011 14:47
you forgot to mention that hydration has a 100% atom economy while fermintation is less than 100% as it also produces CO2 as a waste product.
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