Physics, Chemistry and Biology: Post your doubts here!

[sma786]

I DO. Paper : http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_S08_qp_6.pdf
Question 5)f)

I wrote that it contains copper, but how can we tell it's an organic salt? (I'm very bad at chemistry, just saying :S )

yeah, see ethanoic acid are green in colour, and their odour is similar to that of vinegar .. so its ethanoic acid or organic salt, hope i helped, best of luck =]

 

[suhaib05]

If anybody has any doubt in chemistry paper 6 , inbox me or tag me here,
Best of luck everybody =]

I'm not sure I understand the last question in O/N 2002: http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w02_qp_6.pdf.

How do I make sure that the solubility is in g/100cm3? And how do I work out solubility after I do the experiment (as the mark scheme says)?

 

[sma786]

I'm not sure I understand the last question in O/N 2002: http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w02_qp_6.pdf.

How do I make sure that the solubility is in g/100cm3? And how do I work out solubility after I do the experiment (as the mark scheme says)?

First, take 100cm volume of water to it, then add the fertilizer to it step by step juuussst until u see excess, then stir well and warm at 30 degrees, filter it, and the residue which will b left in the filter paper, take it, dry it, and then weigh it and u got it =]

 

[ZainH]

yeah, see ethanoic acid are green in colour, and their odour is similar to that of vinegar .. so its ethanoic acid or organic salt, hope i helped, best of luck =]

Ahh. All right thanks , expect a few more questions x)
(Sorry for the late reply, was eating dinner >.>)

 

[sma786]

Ahh. All right thanks , expect a few more questions x)
(Sorry for the late reply, was eating dinner >.>)

=] glad i cud help
Yeah sure no problem

 

[ZainH]

If anybody has any doubt in chemistry paper 6 , inbox me or tag me here,
Best of luck everybody =]

Got another question..
Paper:http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s09_qp_6.pdf
Q1)c) I know that crystals can form by heating till crystallisation point, but since it's 2 marks the mark scheme also says using a glass rod?
How the hell do crystals form by using a glass rod -___-?

 

[ZainH]

=] glad i cud help
Yeah sure no problem

Also when you get the time, question 5)c)iii) from paper:http://www.xtremepapers.com/papers/CIE/Cambridge%20IGCSE/Chemistry%20(0620)/0620_s09_qp_6.pdf

I don't need the answer, just an explanation.

 

[Yousif Mukkhtar]

Also when you get the time, question 5)c)iii) from paper:http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s09_qp_6.pdf

I don't need the answer, just an explanation.

Because sulphuric acid is present with solid S. The dilute nitric acid and barium chloride react with the sulphate ions.

 

[ZainH]

Because sulphuric acid is present with solid S. The dilute nitric acid and barium chloride react with the sulphate ions.

There is no dilute nitric acid, its hydrochloric acid..

 

[Yousif Mukkhtar]

There is no dilute nitric acid, its hydrochloric acid..

Read C. It says:

Dilute sulfuric acid was added to solid
S in a test-tube. The mixture was
heated to boiling point

 

[ZainH]

Read C. It says:

Dilute sulfuric acid was added to solid
S in a test-tube. The mixture was
heated to boiling point

Yeah there is sulfuric acid, but you said nitric acid.. where does the nitric acid come from? :S

 

[Yousif Mukkhtar]

Yeah there is sulfuric acid, but you said nitric acid.. where does the nitric acid come from? :S

I meant dilute sulfuric acid. Sorry lol.

 

[ZainH]

I meant dilute sulfuric acid. Sorry lol.

Is this a test for sulphates?
Because in a test for halides, barium chloride would only form a white precipitate if nitric acid was added.. but we added sulfuric acid, not sure what test that is :S

 

[ZainH]

Just checked my book, never mind! I got the answer, thanks though!

 

[Yousif Mukkhtar]

Is this a test for sulphates?
Because in a test for halides, barium chloride would only form a white precipitate if nitric acid was added.. but we added sulfuric acid, not sure what test that is :S

Yeah this is a test for sulphates.

 

[sma786]

ZainH need help now ..?

 

[sma786]

This is a website that i thought u may benefit from for this wednesday...
4 the flame tests, precipitation..and all that...
http://www.freezeray.com/flashFiles/identifyingSalts.htm
4 rates of reaction...
http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa/chemreac/rates.shtml
4 all the quantitave chemistry...
http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa/chemcalc/chemcalcact.shtml
4 all the information u need 2 knoe bout gases...
http://www.bbc.co.uk/schools/gcsebitesize/science/edexcel/chemicalreactions/preparinggasesact.shtml
===> SUMMARY...that works more as a check list...
Summary
You should know that:
-there is a series of tests that help us to analyse substances
-in inorganic chemistry these tests help us to fi nd which positive ions (metals) and negative ions are present in an ionic compound
-there is also a series of tests for gases such as hydrogen, oxygen, etc.
-these analytical ideas can also be applied in organic chemistry
-quantitative experiments, such as titrations, which tell us how much of a substance we have (not just which substance we have),
can be carried out
-in carrying out experiments it is important to control the situation so that not too many conditions are changing at once
-when reporting on experiments it is important to be able to present the results clearly; possibly in a table or by plotting a graph
-this develops into the ideas of a fair test and a controlled experiment – ideas central to any experimental investigation
-the scientifi c method is based in part on these ideas, so that any hypothesis can be properly tested.
HOPE ITS USEFUL <3<3

 

[MNU]

ok just a random doubt in reactions of metals and acids which are exothermic, if the vol of acid is increased will the temp rise also increase?

 

[thats_me]

ok just a random doubt in reactions of metals and acids which are exothermic, if the vol of acid is increased will the temp rise also increase?

i guess wen volume is increased the temp will decrease

 

[za Shadow]

http://www.gcsescience.com/o55.htm

thanks