Author Topic: CHEM AND BIO HELP AND TIPS HERE  (Read 350966 times)

Offline nits94

  • SF Citizen
  • ***
  • Posts: 154
  • Reputation: 172
  • Gender: Female
Re: ~~~All Chemistry Doubts Here~~~
« Reply #180 on: November 11, 2009, 03:26:20 pm »
but isnt it always H2 and not H+???
Choosy mothers choose studies... ;)

Offline $!$RatJumper$!$

  • SF Geek
  • ****
  • Posts: 311
  • Reputation: 5149
  • Gender: Male
Re: ~~~All Chemistry Doubts Here~~~
« Reply #181 on: November 11, 2009, 03:28:27 pm »
no not always... Hydrogen can also b expressed as an ion.. it just depends on the question...

Offline nits94

  • SF Citizen
  • ***
  • Posts: 154
  • Reputation: 172
  • Gender: Female
Re: ~~~All Chemistry Doubts Here~~~
« Reply #182 on: November 11, 2009, 03:29:18 pm »
o got it :) :)
« Last Edit: November 11, 2009, 03:31:21 pm by nits94 »
Choosy mothers choose studies... ;)

Offline adorabledaughter_07

  • Newbie
  • *
  • Posts: 34
  • Reputation: 46
Re: ~~~All Chemistry Doubts Here~~~
« Reply #183 on: November 11, 2009, 03:30:37 pm »
i thought aditox ws rite..bt how cn hydrogen combine wid o2?..Ca is mor reactive rite??
nits..its hydrogen ions..so h+..
"Never say a problem is difficult, because if it were not difficult,it wudnt be a problem!"

Offline @d!_†oX!©

  • SF Master
  • ******
  • Posts: 1268
  • Reputation: 2105
  • Gender: Male
Re: ~~~All Chemistry Doubts Here~~~
« Reply #184 on: November 11, 2009, 03:31:11 pm »
arrey nits u gotta understand this...
its not a normal reaction between hydrogen and calcium oxide...
its the reaction for the treatment of acidity of the soil
so here H+ represents the ion from the acid...
u get it now??
AAL IZZ WELL!!! ;)

Offline nits94

  • SF Citizen
  • ***
  • Posts: 154
  • Reputation: 172
  • Gender: Female
Re: ~~~All Chemistry Doubts Here~~~
« Reply #185 on: November 11, 2009, 03:31:47 pm »
ya fine Thanks :) :) got confused
Choosy mothers choose studies... ;)

Offline eightAs

  • SF Immigrant
  • **
  • Posts: 58
  • Reputation: 134
  • Gender: Male
  • Math geek
Re: ~~~All Chemistry Doubts Here~~~
« Reply #186 on: November 11, 2009, 03:32:44 pm »
hw??? I dint get it
CaO + H+(1) ---> Ca2+ + H2O(2)
H at (1) exists as an ion cos its from an acid. An acid ionizes completely or partially, meaning they split up into ions. eg.: HCl splitting into H+ and Cl-. At (2) its not H+ and OH- cos water is formed which does not ionize. I hope you get it.
Coldplay FTW!

Offline adorabledaughter_07

  • Newbie
  • *
  • Posts: 34
  • Reputation: 46
Re: ~~~All Chemistry Doubts Here~~~
« Reply #187 on: November 11, 2009, 03:39:49 pm »
question- how doz hydrogn combine wid O2? ca is mor reactive>
"Never say a problem is difficult, because if it were not difficult,it wudnt be a problem!"

Offline @d!_†oX!©

  • SF Master
  • ******
  • Posts: 1268
  • Reputation: 2105
  • Gender: Male
Re: ~~~All Chemistry Doubts Here~~~
« Reply #188 on: November 11, 2009, 03:41:55 pm »
here we are not talking about a displacement reaction...its a neutralization reaction where water has to form by combing H and OH/O
do u get it now??
AAL IZZ WELL!!! ;)

Offline ruchir.sakhrani

  • Newbie
  • *
  • Posts: 12
  • Reputation: 22

Offline @d!_†oX!©

  • SF Master
  • ******
  • Posts: 1268
  • Reputation: 2105
  • Gender: Male
Re: ~~~All Chemistry Doubts Here~~~
« Reply #190 on: November 11, 2009, 03:45:01 pm »
that's paper 1...
what do u mean by 4 b 2 and 4 b 3??????????
AAL IZZ WELL!!! ;)

Offline ~~~~shreyapril~~~~

  • SF Master
  • ******
  • Posts: 2606
  • Reputation: 2640
  • Gender: Male
  • "Prototype"
Re: ~~~All Chemistry Doubts Here~~~
« Reply #191 on: November 11, 2009, 03:45:22 pm »
this is MCQ question!!
how can you expect 4b2 and 4b3???
Friendship is like peeing on yourself. Everyone can see it but only you get the warm feeling that it gives :D :P :)

Offline adorabledaughter_07

  • Newbie
  • *
  • Posts: 34
  • Reputation: 46
Re: ~~~All Chemistry Doubts Here~~~
« Reply #192 on: November 11, 2009, 03:47:47 pm »
@aditoxic- oh got it..din notiz dat..thankz! :)
« Last Edit: November 11, 2009, 03:49:47 pm by adorabledaughter_07 »
"Never say a problem is difficult, because if it were not difficult,it wudnt be a problem!"

Offline ruchir.sakhrani

  • Newbie
  • *
  • Posts: 12
  • Reputation: 22

Offline Ghost Of Highbury

  • O_o_O lala!
  • SF Farseer
  • *******
  • Posts: 4096
  • Reputation: 41428
  • Gender: Male
  • Namaskaram!
Re: ~~~All Chemistry Doubts Here~~~
« Reply #194 on: November 11, 2009, 04:11:27 pm »
4bii) first understand the q.

       FeCl3 + 3NaOH --> Fe(OH)3 + 3NaCl

moles of FeCl3 = conc. * volume = 1 * 4/1000 = 0.004

MOles of NaOH = 0.004*3 = 0.012 or conc. * volume = 1 * 12/1000 (look at graph)  = 0.012

when FeCl2 is used, this is the equation

FeCl2 + 2NaOH --> Fe(OH)2 + 2NaCl

Moles of FeCl2 = conc. * volume = 0.004

but here, the mole ratio is 1:2

so the moles of NaOH = 0.004 * 2 = 0.008

volume = moles/conc. = 0.008/1 = 0.008dm^3 = 8cm^3

thus, for FeCl2 --> 8cm^3 of NaOH reacts completely with FeCl2, so, the shape wud be same, only it wud become constant (parallel to x-axis) at 8cm^3 of NaOH
divine intervention!