Biology; Chemistry; Physics: Post your doubts here!

[Rimsa]

OKAY ITS TIME FOR CHEMISTRY NOW GUYS!!!!!!!!! What's the main topics in ATP?

Identification Of Ions
Moles/Titration
Preparation of Salts
Apparatus
Diffusion

electrolysis, thermochem, organics

 

[Rimsa]

Aqueous is aqueous. Why are you guys fighting over it being conc. or dilute? :/
Aqueous solution is simply a solution of a substance in water. The solution contains the +ve & -ve ions of the substance dissolved and water (H+ & OH-)
I never troubled myself into thinking whether it would be dilute or not, so I never assumed unless it was mentioned!

you need to know that in questions of electrolysis

 

[asd]

you need to know that in questions of electrolysis

eH?
any example?

 

[Rimsa]

eH?
any example?

http://www.xtremepapers.com/papers/...al O Level/Chemistry (5070)/5070_s05_qp_4.pdf q3 part c

 

[syed1995]

electrolysis, thermochem, organics

Thermochem ? what would that include :O

 

[Rimsa]

Thermochem ? what would that include :O

umm the question that has thermometer reading? usually the last question of the paper. the one that has graph usually. its last parts are pretty tricky :s

 

[malay]

Aqueous is aqueous. Why are you guys fighting over it being conc. or dilute? :/
Aqueous solution is simply a solution of a substance in water. The solution contains the +ve & -ve ions of the substance dissolved and water (H+ & OH-)
I never troubled myself into thinking whether it would be dilute or not, so I never assumed unless it was mentioned!

LOLL.... A* confirmed

 

[asd]

LOLL.... A* confirmed

LMAOO. Sarcasm?

 

[Rimsa]

part b here. marking scheme says white 'powder'. why powder?

 

[snoonono]

does any1 have a list of all laboratory equipment we need to learn for chem ppr 6

 

[asd]

part b here. marking scheme says white 'powder'. why powder?
View attachment 10403

In heating, water will be evaporated and the crystal structure will break into powder form. I guess...
And since the metal is sodium, group 1 metal, its carbonate will be white.

 

[ayeshaK]

part b here. marking scheme says white 'powder'. why powder?
View attachment 10403

Sodium carbonate naturally occurs in small crystals. When the base of sodium (which is not usually very chemically reactive) comes into contact with carbonic acid, the resulting chemical reaction forms sodium carbonate. While it is formed in crystals, sodium carbonate looks like a plain, white powder to most people who see it. This process naturally occurs

 

[Dukeofwin]

what are you saying confusing everyone about the question change and pattern change??? If there was to be any difference in paper, a specimen paper would have been given! what is ur source about this other than ur teacher?

Please do not post material which may cause other people to die of heart attack as they have the paper the next day!

I simply had no idea people here would be shocked so much!
No other source other than my teacher!

if not mentioned, it is concentrated. A long and lengthy discussion has been held before on this same thread, and it was finally proved from the ms that if mentioned only aqueous, NaCl is always taken conc. and btw, only electrolysis of conc. sodium chloride is included in our syllabus!

No arguing, people would pick whatever they want! But if you just forget the ms and think logically than AQUEOUS means 'added with water'
and DILUTE means 'particles of solution e.g sugar are less than water'
Which by the fact seems dilute!
And as for getting correct except for paper that confused everyone i've got it right!

 

[Dukeofwin]

Aqueous is aqueous. Why are you guys fighting over it being conc. or dilute? :/
Aqueous solution is simply a solution of a substance in water. The solution contains the +ve & -ve ions of the substance dissolved and water (H+ & OH-)
I never troubled myself into thinking whether it would be dilute or not, so I never assumed unless it was mentioned!

Same here, but the fact that it involves (H+ & OH- ions) further proves it that its dilute!
Why dont people open Christopher N.Prescot book it has everything written in topic 9.6!
SIMPLY RIDICULOUS

 

[beeloooo]

hey can someone help me with the formula !! g/dm3 one ..?? i have no idea about it

 

[asd]

that's concentration. amount of a substance in 1 dm3 (1 litre)

 

[asd]

Same here, but the fact that it involves (H+ & OH- ions) further proves it that its dilute!
Why dont people open Christopher N.Prescot book it has everything written in topic 9.6!
SIMPLY RIDICULOUS

Well, this may be a little hurting but i reviewed a few past papers and aq. NaCl is always considered concentrated, idk why but it is. UNLESS the question mentions dilute NaCl solution, its ALWAYS concentrated.

 

[ayeshaK]

Well, this may be a little hurting but i reviewed a few past papers and aq. NaCl is always considered concentrated, idk why but it is. UNLESS the question mentions dilute NaCl solution, its ALWAYS concentrated.

^agreed !!!

 

[Dukeofwin]

Well, this may be a little hurting but i reviewed a few past papers and aq. NaCl is always considered concentrated, idk why but it is. UNLESS the question mentions dilute NaCl solution, its ALWAYS concentrated.

Well apart from NaCl the logic says aq. means dilute! Thats what i'm talking about!

 

[Dukeofwin]

Oh now i understand why people are saying that aqueous is considered concerntrated!
In aqueous NaCl instead of Oxygen at the anode Chlorine is produced because Chlorine is more conerntrated than Oxygen!
While at the cathode same hydrogen is produced!
Refer to Question 3 in June 2008! If you considered it as concerntrated than at the cathode no gas would have formed rather Na would have deposited!

Only chlorine gas is more concerntrated than Oxygen! Thats why people are that for NaCl ONLY you take Aqueous as Concerntrated!
Now i have got it all cleared! Ask your sources, this info is also mentioned in the book!