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Author Topic: IGCSE CHEMISTRY DOUBTS HERE !!!!  (Read 20308 times)

Freaked12

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Re: IGCSE CHEMISTRY DOUBTS HERE !!!!
« Reply #30 on: October 10, 2010, 11:29:25 am »
Stop being a cynic man

Appreciate whatever help people give in any quantity from any source.


+Rep Ivo
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Offline Deadly_king

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Re: IGCSE CHEMISTRY DOUBTS HERE !!!!
« Reply #31 on: October 10, 2010, 11:43:03 am »
Quote from: Requiem on October 10, 2010, 11:29:25 am
Stop being a cynic man

Appreciate whatever help people give in any quantity from any source.


+Rep Ivo
Hey am not being cynic......just wanted to let him know :D
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Offline Blizz_rb93

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Re: IGCSE CHEMISTRY DOUBTS HERE !!!!
« Reply #32 on: October 10, 2010, 11:49:02 am »
Can anyone tell me what are the main topics focused in chemistry paper 6? thank u
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elemis

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Re: IGCSE CHEMISTRY DOUBTS HERE !!!!
« Reply #33 on: October 10, 2010, 11:53:29 am »
Quote from: Blizz_rb93 on October 10, 2010, 11:49:02 am
Can anyone tell me what are the main topics focused in chemistry paper 6? thank u

Know the names of basic equipment.

Know ALL the tests and results for Anions and Cations.

Be prepared to describe the experimental procedure for a simple experiment - like a titration.

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Offline Blizz_rb93

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Re: IGCSE CHEMISTRY DOUBTS HERE !!!!
« Reply #34 on: October 10, 2010, 11:57:46 am »
Quote from: Ari Ben Canaan on October 10, 2010, 11:53:29 am
Know the names of basic equipment.

Know ALL the tests and results for Anions and Cations.

Be prepared to describe the experimental procedure for a simple experiment - like a titration.


oh okay then
the apparatus i know and the tests and results for anions and cations but can you explain to me titration, i really dont understand the coencept, why do they use and which conditions are needed and etc

thank you
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elemis

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Re: IGCSE CHEMISTRY DOUBTS HERE !!!!
« Reply #35 on: October 10, 2010, 12:00:10 pm »
http://www.echeat.com/essay.php?t=30794

Read it.

Got questions post here ;)
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Offline Ivo

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Re: IGCSE CHEMISTRY DOUBTS HERE !!!!
« Reply #36 on: October 17, 2010, 12:27:00 am »
Ammonium sulfate was prepared by adding ammonia solution to 25 cm3 of 2.0 mol dm-3 sulfuric acid.

2NH3(aq) + H2SO4(aq) --> (NH4)2SO4(aq)

Question:

i) What volume of 2.0 mol dm-3 ammonia solution will just neutralise the sulfuric acid?  I got 50 cm3.

ii) How could you test to check that enough ammonia has been added to neutralise the sulfuric acid?

Thanks in advance!
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Offline ashish

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Re: IGCSE CHEMISTRY DOUBTS HERE !!!!
« Reply #37 on: October 17, 2010, 06:27:57 am »
Quote from: Ivo on October 17, 2010, 12:27:00 am
Ammonium sulfate was prepared by adding ammonia solution to 25 cm3 of 2.0 mol dm-3 sulfuric acid.

2NH3(aq) + H2SO4(aq) --> (NH4)2SO4(aq)

Question:

i) What volume of 2.0 mol dm-3 ammonia solution will just neutralise the sulfuric acid?  I got 50 cm3.

ii) How could you test to check that enough ammonia has been added to neutralise the sulfuric acid?

Thanks in advance!

i got 50 cm3 too

ii)test with and indicator such as methyl orange,  if is acidic it turns red and in alkaline medium it turns yellow .. the solution should be neutral so it should remains orange

or use universal indicator, which turns green
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nid404

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Re: IGCSE CHEMISTRY DOUBTS HERE !!!!
« Reply #38 on: October 17, 2010, 06:30:07 am »
First answer is right.

Use an indicator...say phenolphthalein. It is colorless in acids. To ensure that the sulfuric acid is completely neutralized, add ammonia until the solution just turns pink.  
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Offline Arthur Bon Zavi

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Re: IGCSE CHEMISTRY DOUBTS HERE !!!!
« Reply #39 on: October 17, 2010, 06:52:31 am »
Quote from: Garfield on October 17, 2010, 06:30:07 am
First answer is right.

Use an indicator...say phenolphthalein. It is colorless in acids. To ensure that the sulfuric acid is completely neutralized, add ammonia until the solution just turns pink.  

Phenolphthalein is used in strong acid - strong base titration!
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Offline ~HyDrOgEn~

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Re: IGCSE CHEMISTRY DOUBTS HERE !!!!
« Reply #40 on: December 29, 2010, 05:30:27 am »
Quote from: Blizz_rb93 on October 10, 2010, 11:49:02 am
Can anyone tell me what are the main topics focused in chemistry paper 6? thank u
KNow all the chemical tests for metals and non metals , as well as hydrocarbons !! , you must know the bromination experiment and the potassium permangentae one , any help ?  ;D
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Offline The Golden Girl =D

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Re: IGCSE CHEMISTRY DOUBTS HERE !!!!
« Reply #41 on: December 29, 2010, 05:33:29 am »
Chromatography

the List of solubility of salts

Titration

how to make Insoluble salts

i.e.ALL the Separating techniques   

Hmm know how to use your Imagination in a Scientific*stuff from the Syllabus *  way for the LAST Question in the paper ;)
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Offline ~Dazzling Star~

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Re: IGCSE CHEMISTRY DOUBTS HERE !!!!
« Reply #42 on: January 11, 2011, 04:42:52 pm »
can anyone explain the past paper question of chemistry ,year 1997 november question no. 4 part f only? :-\ ???
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elemis

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Re: IGCSE CHEMISTRY DOUBTS HERE !!!!
« Reply #43 on: January 11, 2011, 04:45:35 pm »
I dont have access to those papers. Can you take a screenshot and put it up here ?
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Offline ~Dazzling Star~

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Re: IGCSE CHEMISTRY DOUBTS HERE !!!!
« Reply #44 on: January 11, 2011, 05:18:55 pm »
Quote from: Ari Ben Canaan on January 11, 2011, 04:45:35 pm
I dont have access to those papers. Can you take a screenshot and put it up here ?
i'll type it..
4 a. 4.2 g of cerium reacted with oxygen to form 5.16g of an oxide of cerium.complete the following to determine the formula of this oxide
  1 . number of moles of cerium used
  2 . mass of oxygen that reacted
  3 . number of moles of oxygen atoms in oxide
  4 . ratio by moles of cerium atoms to oxygen atoms
  5 . formula of cerium oxide is
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