AS Chemistry Doubts

[riry]

Hi , please i need answer for question 19 May June 2009 paper 1 ( about chiral centre )

 

[zainab1661]

2 Use of the Data Booklet is relevant to this question.
A typical solid fertiliser for use with household plants and shrubs contains the elements N, P, and
K in the ratio of 15g : 30g :15g per 100 g of fertiliser. The recommended usage of fertiliser is 14g
of fertiliser per 5dm of water.
What is the concentration of nitrogen atoms in this solution?
A 0.03moldm
B 0.05moldm
C 0.42moldm
D 0.75moldm

 

[zainab1661]

6 The density of ice is 1.00gcm.
What is the volume of steam produced when 1.00 cm of ice is heated to 323 °C (596 K) at a
pressure of one atmosphere (101kPa)?
[1mol of a gas occupies 24.0dm at 25°C (298K) and one atmosphere.]
A 0.267dm
B 1.33dm
C 2.67dm
D 48.0dm

 

[zainab1661]

15 Use of the Data Booklet is relevant to this question.
The combustion of fossil fuels is a major source of increasing atmospheric carbon dioxide, with a
consequential rise in global warming. Another significant contribution to carbon dioxide levels
comes from the thermal decomposition of limestone, in the manufacture of cement and of lime for
agricultural purposes.
Cement works roast 1000 million tonnes of limestone per year and a further 200 million tonnes is
roasted in kilns to make lime.
What is the total annual mass output of carbon dioxide (in million tonnes) from these two
processes?
A 440 B 527 C 660 D 88

 

[zainab1661]

Remember that H2SO4 is a dehydrating agent, it'll remove that OH and you'll end up with a double bond...
I'll leave it up to you to find the answer: you'll remember it better...

Lol thanks i understand it and surely won't forget

 

[riry]

please question 19 may june 2009 paper1

 

[riry]

pleeeeeeeeease urgent

 

[workaholic]

Dude read the question carefully: it say HSO4^- is acting as a base; that is where the whole problem started form!

Oops..................My mistake......Sorry!!!
Here's the correction:
HSO3- ion is acting as a base as it donates a OH^- ion to the H+ ion to form water and it is always the base that loses OH^- to form water...........

 

[zainab1661]

Who over here has done their AS chemistry????

 

[riry]

also question 21 October November 2004 paper 1

thank you Scafalon40 for reply

 

[riry]

I know all concepts in chemistry but i m not getting high score for paper 1
sometime 30 and in other papers 28 and i need A what to do and in mock i got high B

 

[riry]

paper 1 is pulling me down

 

[riry]

but in some cases 28 and more worse is 24 and i don't know what to do i am practicing but scared

 

[riry]

if u can say what is your result

 

[riry]

thank u for your advices

 

[riry]

thank uuuuuuuuuuuuu

 

[smartangel]

But shouldn't you be able to explain that in terms of the Bronsted Lowery theory of bases, or in terms of Lewis bases.
I can't explain it with either!
That old 'base releases OH^-' ions thing is...well..old.

i still dont get why the answer is A! could you please explain! in rxn 1 water donates proton hence its an acid..therefore Hso2 will be its conjugate base. ok this makes sense. in rxn 2 Hso3 is losing its proton so doesnt that make it an acid? its rxn two in confused in if anyone could help me out with it.

 

[zainab1661]

paper 1 is pulling me down

Same here, i'm doomed for paper 1

 

[zainab1661]

I'm failing paper 1 seriously :O

 

[TSZ]

http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_s07_qp_1.pdf
ok, for this year, my questions are Q.9, Q.13, Q.18 and Q.34
http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_s03_qp_1.pdf
in this i can't understand Q.33