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Author Topic: CHEM AND BIO HELP AND TIPS HERE  (Read 344791 times)

Offline mdwael

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2850 on: June 06, 2010, 03:09:33 pm »
Quote from: MasterMath on June 06, 2010, 02:57:54 pm
Any metal Above Ca reacts to give a hydroxide and H2.. im talking about the order in reactivity series..
I dont know the place for caesium and lanathium in the reactivity series
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Offline Adzel

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2851 on: June 06, 2010, 03:16:41 pm »
Quote from: ~VIN1094~ on June 06, 2010, 03:05:24 pm
By the way you don;t have to know the structures.

I saw this question in O/N 2002 03, Q 4 (ii)  ::)
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Offline Ivo

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2852 on: June 06, 2010, 03:18:03 pm »
By the way, for some questions they ask how to concentrate something (eg aqeous ethanol).  What does it mean, like add more acid to concentrate, or remove water?

Also, what does saturated solution mean?  I don't mean the stuff about alkanes, the other definition.
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Offline WARRIOR

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2853 on: June 06, 2010, 03:18:39 pm »
link please :/
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Offline WARRIOR

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2854 on: June 06, 2010, 03:20:14 pm »
Quote from: Ivo on June 06, 2010, 03:18:03 pm
By the way, for some questions they ask how to concentrate something (eg aqeous ethanol).  What does it mean, like add more acid to concentrate, or remove water?

Also, what does saturated solution mean?  I don't mean the stuff about alkanes, the other definition.
you havae to evaporate the water (in case of ethanol i think u have to use fractional distillation )

sat solution means  contains maximum amount of solute in a solvent( or maximum amoutn of dissolved material ) in a particulare temprature
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Offline Helium

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2855 on: June 06, 2010, 03:21:29 pm »
Quote from: CatAly$t on June 06, 2010, 03:04:39 pm
what the hell r u talking abt??

Here, check this example.When iron reacts with sulphur the equation is

Fe + S --> FeS

This indicates that we need equal numbers of atoms iron and sulphur to react.
It is known that 1 mol of iron (56g) and 1 mol of sulphur (32g) contain the same number of atoms.
So reacting these amounts should give 1 mole of iron(ll)sulphide (88g). look at equation

Fe       +        S      --->       FeS
1mol           1mol                 1mol
56g             32g                  88g

they can be scaled down, however they mmust always be ratio 56:32

thus

Fe   +   S  ---> FeS
5.6g     3.2g      8.8

If we tried to 5g of S with 5,6 of iron the excess sulphur would remain unreacted
only 3.2g of sulphur will react.  Sulphur is excess omm...   

 ;) most important thing is that the reaction does not require a catalyst :P
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Offline saleemsamer

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2856 on: June 06, 2010, 03:22:38 pm »
NOV 09 p3 q4c and 5b PLZ AND Thank You IN ADVANCE :)
« Last Edit: June 06, 2010, 03:26:14 pm by saleemsamer »
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Offline WARRIOR

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2857 on: June 06, 2010, 03:29:47 pm »
Quote from: saleemsamer on June 06, 2010, 03:22:38 pm
NOV 09 p3 q4c and 5b PLZ AND Thank You IN ADVANCE :)

both asnwrs have been discussed befre , if u go back a few pages ull find them!
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NO secrets to SUCCESS , it is the result of 1.HARD WORK 2.GOOD PREPARATION 3.LEARNING FROM FAILURE
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Offline Helium

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2858 on: June 06, 2010, 03:31:19 pm »
Quote from: saleemsamer on June 06, 2010, 03:22:38 pm
NOV 09 p3 q4c and 5b PLZ AND Thank You IN ADVANCE :)
They have been solved by vin

here they are  https://studentforums.biz/index.php/topic,1411.2820.html

In this past paper there are 4 drawing questions ;)
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Offline Helium

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2859 on: June 06, 2010, 03:32:32 pm »
Quote from: Kimo Jesus on June 06, 2010, 03:29:47 pm
both asnwrs have been discussed befre , if u go back a few pages ull find them!
ur 777th post lol :D
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Offline WARRIOR

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2860 on: June 06, 2010, 03:34:55 pm »
Quote from: Helium on June 06, 2010, 03:32:32 pm
ur 777th post lol :D
beoign 777  8)

i think that exists ^
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Offline Helium

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2861 on: June 06, 2010, 03:37:29 pm »
Quote from: Helium on June 06, 2010, 02:32:38 pm
It's not that I'm bad at balancing just had difficulties

doing this one ;)
So can anyone bother doing this, I got an answer which is correct,
But found it different that the marking scheme.
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Offline Ghost Of Highbury

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2862 on: June 06, 2010, 03:39:49 pm »
C4H9OH + 6O2 ==> 4CO2 + 5H2O
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Offline Vin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2863 on: June 06, 2010, 03:40:24 pm »
Quote from: Helium on June 06, 2010, 03:37:29 pm
So can anyone bother doing this, I got an answer which is correct,
But found it different that the marking scheme.

C4H9OH  +  6O2  ----> 4CO2  +  5H2O

yup whats the answer given?
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Offline WARRIOR

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2864 on: June 06, 2010, 03:41:04 pm »
Quote from: Helium on June 06, 2010, 03:37:29 pm
So can anyone bother doing this, I got an answer which is correct,
But found it different that the marking scheme.

1 ... 6...4....5

yeah u guys are right :p
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NO secrets to SUCCESS , it is the result of 1.HARD WORK 2.GOOD PREPARATION 3.LEARNING FROM FAILURE
But it ain't how hard you hit; it's about how hard you can get hit, and keep moving forward-Balboa
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