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Author Topic: CHEM AND BIO HELP AND TIPS HERE  (Read 333126 times)

Offline Raywin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2895 on: June 06, 2010, 04:56:47 pm »
Quote from: Dana on June 06, 2010, 04:54:18 pm
thats when the equation involves only gases. then you can use mole volume ratio or whatever is called :P

Only gases huh? Lol, ryte, so in that case we can guess how much of something is formed (the volume) using the mole ratios? Thx.. :)
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Offline MasterMath

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2896 on: June 06, 2010, 04:57:07 pm »
Quote from: Raywin on June 06, 2010, 04:52:42 pm
Guys, this has been bugging me. In some papers, the mole concept Q, sometimes the easy way to solve the problems is to use something like the volume ratio is same as the mole ratio or something. Umm, what is this and when can we use this? Thanks a lot in advance. :)
take this reaction for example:
    2N2     +      3H2   -----> 2NH3
          56g                            6g                         34g
Now you can use this for example if they tell you we gave you 5.6g of nitrogen.. how many grams will be produced of hydrogen
Then you can do this
      56              6
      5.6             x
then find X by .. (5.6*6)/56
The same can be done
If you change it
The mole ratio is simply the co-officent of the reactants and products
        2                                        3                             2
just follow the same if they give you a specific amount of moles of reactant/product!
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Offline NidZ- Hero

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2897 on: June 06, 2010, 04:57:27 pm »
why does acid and salt water speed up de rate of rusting
can sum1 plz answer this
ASAP
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Offline The Hitman

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2898 on: June 06, 2010, 04:57:51 pm »
Yo, I needed to ask, why does water act as a base when Sulphuric Acid dissolves in it?
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Offline Raywin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2899 on: June 06, 2010, 04:58:07 pm »
Quote from: MasterMath on June 06, 2010, 04:53:30 pm
Hmm .. look at this
                 K
                 Na
                 Li
                 Ca
                 Mg
                 Al
                 C
                 Zn
                 Fe
                 Pb
                 H
                 Cu
                 Ag
Okay thats the reactivity series .. as you go down reactivity decreases .. ANY METAL ABOVE Ca .. reacts with COLD water to form hydroxide and H2
Anything under it forms oxide and H2 :D
Hope i helped

Umm, i remember seeing MgOH.. O.O  :S
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Offline MasterMath

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2900 on: June 06, 2010, 04:58:22 pm »
Quote from: Dana on June 06, 2010, 04:55:33 pm
you did thanks loads :D what abt calcium does it form a hydroxide or oxide?
Hyrdoxide .. always remember lime water :P ..
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Offline Lariemeeva

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2901 on: June 06, 2010, 04:58:39 pm »
Why is everyone misunderstanding it. Fine, let me rephrase the whole thing in a language that everyone can understand.
I know like hell that cracking goes like this [Alkanes --> Alkene + Hydrogen]. This part understood?

Now in the Mark scheme they say that the answer to my question should be Alkane --> Alkene + Alkane + Hydrogen.

Get it? Now I want to know why they stated Alkane as a product in cracking. I'm not asking for a miracle.

So here's the link, and I hope a sensible person can answer me.
https://studentforums.biz/index.php/topic,54.msg253414.html#msg253414
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Offline MasterMath

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2902 on: June 06, 2010, 04:59:13 pm »
Quote from: Raywin on June 06, 2010, 04:58:07 pm
Umm, i remember seeing MgOH.. O.O  :S
IM 100% sure its MgO :P
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Offline 8T

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2903 on: June 06, 2010, 04:59:50 pm »
Could someone please explain may june 09 paper 32 q 5 b
I know it's for instance K3PO4 or T3 PO4.. but the other 2 marks not quite so any help??
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Offline MasterMath

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2904 on: June 06, 2010, 05:00:53 pm »
Quote from: Lariemeeva on June 06, 2010, 04:58:39 pm
Why is everyone misunderstanding it. Fine, let me rephrase the whole thing in a language that everyone can understand.
I know like hell that cracking goes like this [Alkanes --> Alkene + Hydrogen]. This part understood?

Now in the Mark scheme they say that the answer to my question should be Alkane --> Alkene + Alkane + Hydrogen.

Get it? Now I want to know why they stated Alkane as a product in cracking. I'm not asking for a miracle.

So here's the link, and I hope a sensible person can answer me.
https://studentforums.biz/index.php/topic,54.msg253414.html#msg253414
First chill off dude .. >_>
And Yes sometimes Alkane can be cracked to give SMALLER CHAIN ALKANE ... this is just HOW IT IS .. >_<
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elemis

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2905 on: June 06, 2010, 05:03:32 pm »
@Larimeeva  I strongly suggest lowering your tone; we are all here to help you, but we are NOT OBLIGED to help you.

Respect others and treat them fairly; most importantly be NICE.
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Offline Raywin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2906 on: June 06, 2010, 05:03:44 pm »
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Offline MasterMath

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2907 on: June 06, 2010, 05:04:15 pm »
Quote from: MasterMath on June 06, 2010, 05:00:53 pm
First chill off dude .. >_>
And Yes sometimes Alkane can be cracked to give SMALLER CHAIN ALKANE ... this is just HOW IT IS .. >_<
And sometimes Alkane-->Alkene + Hydrogen or Alkene + alkane .. or Alkane+ hydrogen or alkane + alkene +hydrogen!
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Offline MasterMath

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2908 on: June 06, 2010, 05:05:21 pm »
Quote from: Raywin on June 06, 2010, 05:03:44 pm
Hehe Wikipedia doesnt think so.. :P :P
http://en.wikipedia.org/wiki/Magnesium_hydroxide
Ugh sigh :P , OFCOURSE Magnesium HYDROXIDE EXISTS OBVIOUSLY.. BUt where talking about the products when magnesium reacts with water .. its MgO :P sorry to disappoint you and your wiki :D
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Offline Dana

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2909 on: June 06, 2010, 05:05:48 pm »
Quote from: MasterMath on June 06, 2010, 04:58:22 pm
Hyrdoxide .. always remember lime water :P ..
omg no it can form both! cuz there are diff types of lime :P slaked lime, quicklime, limestone
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