CHEM AND BIO HELP AND TIPS HERE

[holtadit]

Exothermice mean energy (heat) given out leading to a temp. rise.

Opposite true for Ednothermic.

[The Golden Girl =D]

Exothermice mean energy (heat) given out leading to a temp. rise.

Opposite true for Ednothermic.

i actually referred my ans to the equilibrium lesson ....whne temp increases , the reaction's decreases

so y my referring thing is wrong ....y in this case i got to refer to urs .....when do i refer to my thiny and when do i refer to urs 

[jellybeans]

Nov 2009
Atom X has 8 more electrons than atom Y.
Student 1 says they are in the same group.
Student 2 says they are unreactive.
Which students can be correct?
   student 1 student 2
A  tick         tick
B   tick         cross
C    cross       tick
D     cross       cross

Answer is A. HOW COME?  

each full outer shell has 8 electrons .. and.. if it was in group one, Li has 3 electrons, plus 8, you get 11. and you add another 8 electrons, you get 19. there's always 1 electron left on the outermost shell. (which shows that they're in the same group) so your answer must be A or B..

then, they 'can' be unreactive as well , cuz for noble gases, Neon has 10 electrons. Plus 8, you get 18 (Ar). plus another 8, 36 (Kr). and there's always gonna be a full outermost shell... (which shows that they're unreactive), so... yeah both students can be right, & its tick for student 1 & 2 so its A.

[luv3life]

Good Bye, people. I'm gona do past papers all night now. Then sleep. Got an exam in less than 12 hours.

Alll the Best for whatever exam you do, especially Chemistry Paper 1.

*** Aim High ***

[holtadit]

i actually referred my ans to the equilibrium lesson ....whne temp increases , the reaction's decreases

so y my referring thing is wrong ....y in this case i got to refer to urs .....when do i refer to my thiny and when do i refer to urs 

for question 15
Dont confuse rates of reactions and equilibrium.

Think about it like this, if I heat you up to 4000 degrees centigrade you will start SHOOTING AROUND THE ROOM.

Thus you collide more often with other atoms and the rate of the reaction increases. Thus answer is D

-------------------------------------------------------------------------------------------------------------------------------------

For equilibrium reactions the RATE of the FORWARD reaction is reduced by a temperature rise.

[Lariemeeva]

Can anyone list down all the colours of Metals, non-metals, gases and everything else that's included in the syllabus for Paper 1? (Including Hydroxide, etc..) There are a lot of questions about it especially in electrolysis.

[The Golden Girl =D]

for question 15
Dont confuse rates of reactions and equilibrium.

Think about it like this, if I heat you up to 4000 degrees centigrade you will start SHOOTING AROUND THE ROOM.

Thus you collide more often with other atoms and the rate of the reaction increases. Thus answer is D

-------------------------------------------------------------------------------------------------------------------------------------

For equilibrium reactions the RATE of the FORWARD reaction is reduced by a temperature rise.
[/quotokay now i get it ..can u plz answer Q35 in same year 

[Vin]

i need help in the followin :

in june 2006 chem paper 1 , i don't undertans y Q 35 is c  (y does the OH bond no.1 not included in the answer  )

ohh and also same year question 15 ...... isn't the reaction exothermic , so y temp has to increase  


thx in a advance

ok here ..

 
    H     OH                                H    Na
    |     /                                    |    /
H- C - C=O    +    NaOH  ---->  H-C- C = O + H2O
    |                                          |
    H                                         H    

This is a simplified reaction showing ethanoic acid reacting with sodium hydroxide to give Sodium ethanoate (salt) and water

in your ques only (2) can be displaced or only that -OH can be displaced

like for eg in HCOOH  only the bold H can be displaced

[The Golden Girl =D]

Can anyone list down all the colours of Metals, non-metals, gases and everything else that's included in the syllabus for Paper 1?

all gases r colourless ....except for Nitrogen dioxide which is brown

as for metals , metals in group one and two are all grey .........transition metals too except for gold which it's colour os golden lik me ..anyways and there is copper that is brown ....adn what else   ...um that's all ..ohh mercury is silver but it's in liquid form

as for non-metals ....group 7 (halogens) .....F is yeelo , Cl is green ,Br is brown , I is grey ,and Astatine thingy is Black ..... that's all i kno

hope i helped  

[The Golden Girl =D]

ok here ..

 
    H     OH                                H    Na
    |     /                                    |    /
H- C - C=O    +    NaOH  ---->  H-C- C = O + H2O
    |                                          |
    H                                         H    

This is a simplified reaction showing ethanoic acid reacting with sodium hydroxide to give Sodium ethanoate (salt) and water

in your ques only (2) can be displaced or only that -OH can be displaced

like for eg in HCOOH  only the bold H can be displaced

aha now i get ,thx mate 

[Lariemeeva]

^^Thanks but I think you missed some.
also,

Can anyone list down all the colours of Metals, non-metals, gases and everything else that's included in the syllabus for Paper 1? (Including Hydroxide, etc..) There are a lot of questions about it especially in electrolysis.

So how do we know the colour of hydroxides and the other stuff?
Check Oct/Nov 2009 P1 Q13, They say that OH- makes the UI colourless. Why?

[CatAly$t]

The best thing to do before a MCQ paper is  --> Get a notebook, make an answer table from 1-40 for each question. Open papers (soft-copy) from 2002, and do the 2002-2009 all night.

In the end, check the answers, mark yourself, and I guarantee , you'll see a hell lotta similar questions popping up in the paper 2morrow.

If u have already done this, sleep well, thats all you need.

thanks!!!u calmed me....

[CatAly$t]

y do we need to dry gas??sometimes they pass a gas through sulfuric acid to dry it. y??

[The Golden Girl =D]

plz answer my folowin Q

in june  2007 ,Q11 , y the no. of atome is 8 y not 9 

oh and in Q 3 same year , y it is 75.5 not 84.5 

plz help

[Vin]

y do we need to dry gas??sometimes they pass a gas through sulfuric acid to dry it. y??

see if this helps u ..

http://www.chem.ucalgary.ca/courses/351/laboratory/drying%20agents.pdf