« previous next »
Pages: 1 ... 5 6 [7] 8 9 ... 25   Go Down

Author Topic: CHEMISTRY PAPER 1 HERE  (Read 38711 times)

Offline Triple_A

  • SF Immigrant
  • **
  • Posts: 69
  • Reputation: -1
  • Gender: Male
Re: CHEMISTRY PAPER 1 HERE
« Reply #90 on: June 11, 2009, 11:53:02 am »
PPL.......Lead Oxide is yellow!!
if it was Iron Oxide then it wont be yellow.......it would be green or reddish brown depend on the valency of iron
Logged
IGCSE insists on clear plastic pencil case
So whats next?!!...............Clear Outfits O.o'
loOoOol

....

  • Guest
Re: CHEMISTRY PAPER 1 HERE
« Reply #91 on: June 11, 2009, 12:06:28 pm »
I stand corrected.
Indeed, lead (II) oxide is yellow and lead (I) oxide is dark brown. And lead (II) carbonate is, undoubtedly, white. Thus answer has to be lead.
Thank you Triple_A.
Logged

Offline sweetest angel

  • Oh dear beach I await...
  • SF Geek
  • ****
  • Posts: 346
  • Reputation: 259
  • Gender: Female
Re: CHEMISTRY PAPER 1 HERE
« Reply #92 on: June 11, 2009, 12:08:00 pm »
Quote from: Priceless on June 11, 2009, 10:34:02 am
ok itz defi sodium 4 da 1st

but guyz 4 da 2nd...itz 'b'.....itz using copper electrodes wich r active electrodes.......im sure u hv don't da purification of copper using electrolysis...itz da same thng

n 3rd.....im not sure but i thnk itz sodium bcuz itz an alkali wich forms white compounds....

plz nid or any1...correct me if im wrong.....thnku
sry ma bad i didnt read copper electordes in da question :-[
Logged
"Dont fear the creation, but fear the creator who has created the creation you fear"
"If you educate a man, you educate an individual, but if you educate a female, you educate a nation"
 I DO WHAT I WANT WHERE I WANT WHEN I WANT if mom says ok.

Offline mizuki

  • Newbie
  • *
  • Posts: 5
  • Reputation: 0
Re: CHEMISTRY PAPER 1 HERE
« Reply #93 on: June 11, 2009, 12:14:51 pm »
hey guys id appreciate some help.may june 03 q21

water is added to dilute H2SO4 of pH4.What is the resulting pH?

the answer is 6,but why?i know it has something to do with the hydroxide or hydrogen ions in water which change its pH....
Logged

Offline girl_92

  • SF Geek
  • ****
  • Posts: 318
  • Reputation: 152
  • Gender: Female
Re: CHEMISTRY PAPER 1 HERE
« Reply #94 on: June 11, 2009, 12:15:54 pm »
Quote from: Triple_A on June 11, 2009, 11:53:02 am
PPL.......Lead Oxide is yellow!!
if it was Iron Oxide then it wont be yellow.......it would be green or reddish brown depend on the valency of iron
r  u sure der was sum1 astar sumthin he said he is a private tutor i so want him to answer this n By the way whr r da big brains those ppl nid n every1
Logged
some people sleep to dream while othrs wakeup to follow dem im the second type how abt u

....

  • Guest
Re: CHEMISTRY PAPER 1 HERE
« Reply #95 on: June 11, 2009, 12:18:09 pm »
Quote from: mizuki on June 11, 2009, 12:14:51 pm
hey guys id appreciate some help.may june 03 q21

water is added to dilute H2SO4 of pH4.What is the resulting pH?

the answer is 6,but why?i know it has something to do with the hydroxide or hydrogen ions in water which change its pH....
Water has a pH of 7, so when it is added to a pH4 substance, it will try to bring the pH of the substance to 7. Since 8 is above 7, it is wrong. The pH can't remain same, and neither can it become further acidic, so it has to be the one that is close to 7, or slightly less than it. That is 6.
Logged

Offline girl_92

  • SF Geek
  • ****
  • Posts: 318
  • Reputation: 152
  • Gender: Female
Re: CHEMISTRY PAPER 1 HERE
« Reply #96 on: June 11, 2009, 12:19:07 pm »
Quote from: mizuki on June 11, 2009, 12:14:51 pm
hey guys id appreciate some help.may june 03 q21

water is added to dilute H2SO4 of pH4.What is the resulting pH?

the answer is 6,but why?i know it has something to do with the hydroxide or hydrogen ions in water which change its pH....
its jus tht it bcums dilute so the pH lowers i think so
Logged
some people sleep to dream while othrs wakeup to follow dem im the second type how abt u

Offline MR.BooMBastiC

  • SF Farseer
  • *******
  • Posts: 4573
  • Reputation: 2621
  • Gender: Male
Re: CHEMISTRY PAPER 1 HERE
« Reply #97 on: June 11, 2009, 12:20:21 pm »
Quote from: mizuki on June 11, 2009, 12:14:51 pm
hey guys id appreciate some help.may june 03 q21

water is added to dilute H2SO4 of pH4.What is the resulting pH?

the answer is 6,but why?i know it has something to do with the hydroxide or hydrogen ions in water which change its pH....

it has nothing to do with hydroxide..

when u add water it becomes diluted so its ph increases...

hope u got it now... :)
Logged

Offline sweetest angel

  • Oh dear beach I await...
  • SF Geek
  • ****
  • Posts: 346
  • Reputation: 259
  • Gender: Female
Re: CHEMISTRY PAPER 1 HERE
« Reply #98 on: June 11, 2009, 12:21:05 pm »
Quote from: mizuki on June 11, 2009, 12:14:51 pm
hey guys id appreciate some help.may june 03 q21

water is added to dilute H2SO4 of pH4.What is the resulting pH?

the answer is 6,but why?i know it has something to do with the hydroxide or hydrogen ions in water which change its pH....
LOW PH+high PH=neutral
high ph+ high ph= alkaline
low ph+ low ph= acidic
 in this case a low ph and a neutral would give u weak acidic only
further xplanation of the results of neutralisation i think is nt needed!

NOW I GOT A QUESTION: NOV08 Q13: y is it B not A?????
Logged
"Dont fear the creation, but fear the creator who has created the creation you fear"
"If you educate a man, you educate an individual, but if you educate a female, you educate a nation"
 I DO WHAT I WANT WHERE I WANT WHEN I WANT if mom says ok.

Offline esso

  • SF Citizen
  • ***
  • Posts: 147
  • Reputation: 25
Re: CHEMISTRY PAPER 1 HERE
« Reply #99 on: June 11, 2009, 12:23:13 pm »
i need help in this question <

 Three reactions used in the manufacture of sulphuric acid are shown.
1 S + O2 ? SO2
2 2SO2 + O2 ? 2SO3
3 SO3 + H2O ? H2SO4
Which of these reactions are redox reactions?
A 1 only
B 3 only
C 1 and 2 only
D 2 and 3 only
Logged

Offline mizuki

  • Newbie
  • *
  • Posts: 5
  • Reputation: 0
Re: CHEMISTRY PAPER 1 HERE
« Reply #100 on: June 11, 2009, 12:25:44 pm »
thanks for your help everyone.

to answer your Q,sweetest angel,its because if it were in solution,the hydrogen would be liberated in preference to lead.
Logged

Offline Clem

  • Newbie
  • *
  • Posts: 20
  • Reputation: 0
Re: CHEMISTRY PAPER 1 HERE
« Reply #101 on: June 11, 2009, 12:26:30 pm »
Hey! Can someone tell me why q4 in november 08 is A? Ionic compounds are soluble in ethanol and water
And also november 2007 no. 21, shouldn' it form a blue percepitate??

Logged

Offline girl_92

  • SF Geek
  • ****
  • Posts: 318
  • Reputation: 152
  • Gender: Female
Re: CHEMISTRY PAPER 1 HERE
« Reply #102 on: June 11, 2009, 12:27:49 pm »
Quote from: sweetest angel on June 11, 2009, 12:21:05 pm
Quote from: mizuki on June 11, 2009, 12:14:51 pm
hey guys id appreciate some help.may june 03 q21

water is added to dilute H2SO4 of pH4.What is the resulting pH?

the answer is 6,but why?i know it has something to do with the hydroxide or hydrogen ions in water which change its pH....
LOW PH+high PH=neutral
high ph+ high ph= alkaline
low ph+ low ph= acidic
 in this case a low ph and a neutral would give u weak acidic only
further xplanation of the results of neutralisation i think is nt needed!

NOW I GOT A QUESTION: NOV08 Q13: y is it B not A?????
they asked u abt the metal lead's bromide so it has to be molten
Logged
some people sleep to dream while othrs wakeup to follow dem im the second type how abt u

Offline girl_92

  • SF Geek
  • ****
  • Posts: 318
  • Reputation: 152
  • Gender: Female
Re: CHEMISTRY PAPER 1 HERE
« Reply #103 on: June 11, 2009, 12:30:19 pm »
Quote from: esso on June 11, 2009, 12:23:13 pm
i need help in this question <

 Three reactions used in the manufacture of sulphuric acid are shown.
1 S + O2 ? SO2
2 2SO2 + O2 ? 2SO3
3 SO3 + H2O ? H2SO4
Which of these reactions are redox reactions?
A 1 only
B 3 only
C 1 and 2 only
D 2 and 3 only
its 1 n 2 i suppose
Logged
some people sleep to dream while othrs wakeup to follow dem im the second type how abt u

Offline sweetest angel

  • Oh dear beach I await...
  • SF Geek
  • ****
  • Posts: 346
  • Reputation: 259
  • Gender: Female
Re: CHEMISTRY PAPER 1 HERE
« Reply #104 on: June 11, 2009, 12:30:48 pm »
Quote from: mizuki on June 11, 2009, 12:25:44 pm
thanks for your help everyone.

to answer your Q,sweetest angel,its because if it were in solution,the hydrogen would be liberated in preference to lead.
i thought dat 2 but lead is higher in reactivity series than hydrogen!! =s
Logged
"Dont fear the creation, but fear the creator who has created the creation you fear"
"If you educate a man, you educate an individual, but if you educate a female, you educate a nation"
 I DO WHAT I WANT WHERE I WANT WHEN I WANT if mom says ok.
Pages: 1 ... 5 6 [7] 8 9 ... 25   Go Up
« previous next »