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Author Topic: Chemistry Help HERE ONLY !!  (Read 106216 times)

Offline lana

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Re: Chemistry Help HERE ONLY !!
« Reply #315 on: May 29, 2009, 04:01:38 pm »
no I'm right exothermic is when energy is given out so the temperature increases and endothermic is when energy is taken so the temperature decreases but i just misunderstood the question that's all ....!!!
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Offline unknown 101

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Re: Chemistry Help HERE ONLY !!
« Reply #316 on: May 29, 2009, 04:05:54 pm »
Quote from: lana on May 29, 2009, 04:01:38 pm
no I'm right exothermic is when energy is given out so the temperature increases and endothermic is when energy is taken so the temperature decreases but i just misunderstood the question that's all ....!!!

actually the first time u asked was wrong , lol, but now u know the right concept, so stop makin a big fuss about it , haha,lol  :P
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Offline idol2009

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Re: Chemistry Help HERE ONLY !!
« Reply #317 on: May 29, 2009, 04:08:09 pm »
Hey I got a question: how are organic/carboxylic acids made? Is it by acidifying, or is it by oxidizing with potassium magnanate(or another oxidizing agent, or both together? Just confused as to if both the methods are correct, and if they are supposed to be used together...
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Offline unknown 101

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Re: Chemistry Help HERE ONLY !!
« Reply #318 on: May 29, 2009, 04:10:05 pm »
Quote from: idol2009 on May 29, 2009, 04:08:09 pm
Hey I got a question: how are organic/carboxylic acids made? Is it by acidifying, or is it by oxidizing with potassium magnanate(or another oxidizing agent, or both together? Just confused as to if both the methods are correct, and if they are supposed to be used together...

carboxlyic acids are usually made by oxidising alcahols ( it doesnt matter which oxidising agent u use)
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Offline unknown 101

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Re: Chemistry Help HERE ONLY !!
« Reply #319 on: May 29, 2009, 04:11:36 pm »
thats why u sometimes get a question in fermintation about why oxygen should not be present in the flask or container
and the ans is because it can oxidise the ethanol into ethanoic acid (vinegar)
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Offline unknown 101

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Re: Chemistry Help HERE ONLY !!
« Reply #320 on: May 29, 2009, 04:21:30 pm »
i wish the 2009 chem paper 3 comes as easy as the jun 08
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Offline emi

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Re: Chemistry Help HERE ONLY !!
« Reply #321 on: May 29, 2009, 04:24:06 pm »
yes lilwayne though i have feelings that it will be
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Offline unknown 101

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Re: Chemistry Help HERE ONLY !!
« Reply #322 on: May 29, 2009, 04:33:45 pm »
Quote from: emi on May 29, 2009, 04:24:06 pm
yes lilwayne though i have feelings that it will be

anywayz if u study properley , everthng is gonna be easy!!!
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Offline annie_angel

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Re: Chemistry Help HERE ONLY !!
« Reply #323 on: May 29, 2009, 04:49:32 pm »
Quote from: ADi...M on May 28, 2009, 02:31:12 pm
yes..correct...forgot lithium
anyway we can change it a bit

peter's sister lauren can murder a ..............

lol
haha
HAHAHAHA!!!!!!!LOL!!!tht is so funny!!!
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Offline Shogun

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Re: Chemistry Help HERE ONLY !!
« Reply #324 on: May 29, 2009, 05:19:57 pm »
lol lil wayne, wat u wanna be when u grow up?
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Offline unknown 101

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Re: Chemistry Help HERE ONLY !!
« Reply #325 on: May 29, 2009, 05:24:52 pm »
Quote from: Shogun on May 29, 2009, 05:19:57 pm
lol lil wayne, wat u wanna be when u grow up?

a doctor or pharmacist... u?
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Offline Summer :]

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Re: Chemistry Help HERE ONLY !!
« Reply #326 on: May 29, 2009, 05:30:03 pm »
Quote from: ZeroZero82 on May 28, 2009, 10:48:27 am
how do we know if a reaction is endothermic?!

If heat was taken in, it's usually shown by a rise in temperature :)))
For example, you could put a thermometer inside and measure the inital temperature then the final temperature, you'll see that the temperature increased

Endothermic is the opposite way around, its shown as a decrease in temperature
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Offline AN10

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Re: Chemistry Help HERE ONLY !!
« Reply #327 on: May 29, 2009, 05:33:58 pm »
During electrolysis, what is the effect of adding water to dilute sulfuric acid on the brightness of bulb ???
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Offline unknown 101

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Re: Chemistry Help HERE ONLY !!
« Reply #328 on: May 29, 2009, 05:35:30 pm »
Quote from: AN10 on May 29, 2009, 05:33:58 pm
During electrolysis, what is the effect of adding water to dilute sulfuric acid on the brightness of bulb ???

it makes the sulphuric acid more dilute, so the bulb's brightness decreases. i think
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Offline X Abdulrahman X

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Re: Chemistry Help HERE ONLY !!
« Reply #329 on: May 29, 2009, 05:39:03 pm »
Quote from: ZeroZero82 on May 28, 2009, 10:48:27 am
how do we know if a reaction is endothermic?!

The temp would fall, this is because it takes more energy/heat to break the bonds between the atoms, if it was exothermic, then more energy would be used to form new bonds, and the temp. raises
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