21
Chemistry / barium sulfate and barium carbonate
« on: 12/10/2009 14:34:31 »
why barium carbonate is much more poisonous than barium sulfate?
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22
Chemistry / Why do alkanes with even numbers of carbon atoms pack more closely?
« on: 11/09/2009 15:04:23 »
what is energetically unstable and kinetically unstable?
23
Chemistry / what is the function of ethane-1,2-diol?
« on: 08/09/2009 09:45:36 »
what is the function of ethane-1,2-diol?
24
Chemistry / Why do alkanes with even numbers of carbon atoms pack more closely?
« on: 06/09/2009 11:50:35 »
"If the double bond is stronger than the single bond, why alkenes are more reactive than alkanes?
When reagents add across the double bond in ethene, the pi bond is broken, this require energy. The energy used in breaking the one pi bond, however, is more than repaid by the energy released when two new bond are made.
Hence, alkenes are energetically unstable relative to their products in an addition reaction. They are also kinetically unstable, because the high electron density in the double bond tends to attract electrophiles, thus initiating addition reactions. "
The statement above is what my lecture tell me. But I can't understand it.
What is energically unstable and kinetically unstable? []
When reagents add across the double bond in ethene, the pi bond is broken, this require energy. The energy used in breaking the one pi bond, however, is more than repaid by the energy released when two new bond are made.
Hence, alkenes are energetically unstable relative to their products in an addition reaction. They are also kinetically unstable, because the high electron density in the double bond tends to attract electrophiles, thus initiating addition reactions. "
The statement above is what my lecture tell me. But I can't understand it.
What is energically unstable and kinetically unstable? [
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26
Chemistry / Re: Why do alkanes with even numbers of carbon atoms pack more closely?
« on: 04/09/2009 16:54:17 »
Why alkane with odd number of carbon atoms packed less closely than alkane with even number of carbon atom?
27
Chemistry / Why do alkanes with even numbers of carbon atoms pack more closely?
« on: 04/09/2009 03:16:14 »
why alkanes with even number of carbon atoms packed more closely in solid state and have higher melting and boiling points?
28
Chemistry / How does water form a membrane to make bubbles?
« on: 26/08/2009 13:30:03 »
chang hui yun asked the Naked Scientists:
When we do experiments , such as the experiment to investigate the effect of temperature on the rate of reaction of an enzyme, gas will be produced and, through a delivery tube, transfer to another test tube that is filled with distilled water. In the distilled water, the gas forms bubbles.
Why does the gas, once it meets water, get wrapped into bubbles? How does the water form a membrane to wrap the gas?
What do you think?
When we do experiments , such as the experiment to investigate the effect of temperature on the rate of reaction of an enzyme, gas will be produced and, through a delivery tube, transfer to another test tube that is filled with distilled water. In the distilled water, the gas forms bubbles.
Why does the gas, once it meets water, get wrapped into bubbles? How does the water form a membrane to wrap the gas?
What do you think?
29
Chemistry / Re: Why does a gas passed into water form bubbles?
« on: 23/08/2009 06:47:16 »
no one can answer me?
33
Chemistry / How does sunlight remove stains?
« on: 20/08/2009 15:28:12 »Prolonged exposure to bright sunlight can lead to yellowing of whites.what react with what will cause the yellowing of whites? can we prevent it? how?
34
Chemistry / Will my noodles absorb Curcumin?
« on: 20/08/2009 15:24:43 »
Sorry, what is curcumin?
35
Plant Sciences, Zoology & Evolution / How do plant tracheids work?
« on: 19/08/2009 11:26:39 »
Hey! EvilFrog also got the same question.... anyone can explain?
36
Chemistry / catalytic converter
« on: 18/08/2009 16:55:37 »
Ha ha! You are right! WHY DON'T DO LIKE THIS? Anyway, thank you for your answer. [
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37
Chemistry / catalytic converter
« on: 18/08/2009 14:23:44 »
what is catalytic converter? what is Pd/Pt/Rh catalyst? []
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