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Author Topic: CHEM AND BIO HELP AND TIPS HERE  (Read 357130 times)

Offline WARRIOR

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2220 on: May 25, 2010, 05:03:40 am »
Quote from: Ari Ben Canaan on May 25, 2010, 05:00:10 am
Your correct; the answer you gave is from a teacher's mark scheme remember that.

alright can u check the firsst post on this page??

and this  1 tooo

whyy?

not B ..lead is also a trans metal
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Offline WARRIOR

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2221 on: May 25, 2010, 05:30:17 am »
asnwer is D???

is it caz CO + O2  is exothermic?
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Offline WARRIOR

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2222 on: May 25, 2010, 05:37:12 am »
why C not A??

i pretended that Mn is a trans metla like silver and lead and so i thought A?
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Offline Lariemeeva

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2223 on: May 25, 2010, 06:02:12 am »
I'm confused, in electrolysis when we say that there's a H2O ion, a substance is concentrated or when it is aqueous?
« Last Edit: May 25, 2010, 06:04:40 am by Lariemeeva »
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Offline WARRIOR

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2224 on: May 25, 2010, 06:05:22 am »
Quote from: Lariemeeva on May 25, 2010, 06:02:12 am
I'm confused, in electrolysis when we say that a substance is concentrated or when it is aqueous that we have to keep in mind there's a H2O ion?

nop not when its concentrated !!!!

ex CONC NA CL

H+  AND CL- WILL FORM !!

and Na will form as a metal deposit!
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Offline WARRIOR

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2225 on: May 25, 2010, 06:19:17 am »
i got my questions answered guys ! from a freind not in sf

thanks ! ( no need to anser them now )
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Offline Lariemeeva

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2226 on: May 25, 2010, 06:52:33 am »
^^So when it's concentrated we say it has H2O?

And another question M/J 2009 Q26.
What does the fact that it's green has to do with anything?
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Offline CatAly$t

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2227 on: May 25, 2010, 07:07:16 am »
pls help me wit this.the answer is B.why?

why the pH does not change when we add NaCl??
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Offline WARRIOR

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2228 on: May 25, 2010, 07:09:25 am »
Quote from: CatAly$t on May 25, 2010, 07:07:16 am
pls help me wit this.the answer is B.why?

why the pH does not change when we add NaCl??

NACL IS A SALT...( NETURAL )

NOT ALKALINE OR ACIDIC.
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Offline WARRIOR

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2229 on: May 25, 2010, 07:11:51 am »
Quote from: Lariemeeva on May 25, 2010, 06:52:33 am
^^So when it's concentrated we say it has H2O?

And another question M/J 2009 Q26.
What does the fact that it's green has to do with anything?

I DUNNO I HAEVA  DIFF VARIANT

By the way if i were id go study electrolysis again caz u haev the whole concept wrong and electrolysis is very common !

CONC . has ntothign to do with water


dilute And aqueos haev somehtin to do with water
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Offline Lariemeeva

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2230 on: May 25, 2010, 07:17:41 am »
Exactly, I actually studied it pretty well and then I read all those posts about concentrated and stuff and they've been pretty confusing since I know that Aq means it is dissolved in water.  

Anyways Oct/Nov 2008 Q3, Why is it Aqueous lead (II) nitrate and not dilute sulfuric acid?

And also M/J 2009 Q26.
What does the fact that it's green has to do with anything?
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Offline CatAly$t

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2231 on: May 25, 2010, 07:26:32 am »
Quote from: Kimo Jesus on May 25, 2010, 07:09:25 am
NACL IS A SALT...( NETURAL )

NOT ALKALINE OR ACIDIC.

ooohh...okay,thanks :D
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Offline ruruiw 60984

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2232 on: May 25, 2010, 07:38:38 am »
srry ,, an emergency question .
why is zinc hydroxide added to sulfuric acid in solid form ?
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Offline Vin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2233 on: May 25, 2010, 07:44:07 am »
Quote from: ruruiw 60984 on May 25, 2010, 07:38:38 am
srry ,, an emergency question .
why is zinc hydroxide added to sulfuric acid in solid form ?

I dont think ZnOH is available in solid for ?!? ???
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Offline Vin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2234 on: May 25, 2010, 08:02:00 am »
Quote from: Kimo Jesus on May 25, 2010, 04:31:15 am
hard one

answer is A ?why

Im kinda confused too ..  :-\

Take this for eg ..
Mg + H2O ---> MgO + H2 .. single displaced reaction .. "convert molecules to a new substance by removing Hydrogen atoms" ..

also, FeS + HCl ---> FeCl2 + H2S  .. double displacement reaction .."convert molecules to a new substance by removing Hydrogen atoms"
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