Qualification > Sciences

IGCSE CHEMISTRY DOUBTS

<< < (24/37) > >>

Ivo:

--- Quote from: ~VIN1094~ on June 04, 2010, 06:57:30 pm ---Elaboration::

1) First reaction, FeCl3 + 3 NaOH ---> 3NaCl  +  Fe(OH)3

so the molar ratio is 1:3 <deduce this ratio by 1)

Second reaction, FeCl2 + 2 NaOH ---> 2NaCl  +  Fe(OH)2

molar ratio 1:2

so 4 cm3 of FeCl2 reacted fully with 8 cm3 of NaOH

Ivo pls. check!

--- End quote ---

Yep, exactly the same!

8T:
THANKS A LOT BOTH :D !

jellybeans:

--- Quote from: Ivo on June 04, 2010, 05:56:27 pm ---D, obviously.  Because during the day, the plants photosynthesise, so causing oxygen levels to increase.  At night, plants and animals respire so release carbon dioxide, thus reducing the oxygen levels.

--- End quote ---

OH. i thought the q meant O2 was already high in the morning. lol, :s ;S hhaahaaah thaaankyo


--- Quote from: ~VIN1094~ on June 04, 2010, 05:57:26 pm ---Is this chemistry ::) :P

i was about to answer :P

By the way which paper? I mean which session?

--- End quote ---

LOLLLLL THANKS and sry  ::) lol /facepalm. totally posted it in the wrong thread  :P :P :P ;D
O/N 06 Bio  :P

gaurav95:

--- Quote from: gaurav95 on June 04, 2010, 12:21:12 pm ---some more doubts coming up...............

q4aii),iii)thensame q bii

q6bi its saying ammoniuum ion and ms is giving test abt nitrate ion............

q7b whole

thx in advance........

--- End quote ---


--- Quote from: Ivo on June 04, 2010, 12:40:43 pm ---4) a) ii) Pb(NO3)2 + 2NaCl -> PbCl2 + 2NaNO3
  
        iii) Ag+ + Cl- -> AgCl

    b) ii) Please click here.

6) b) i) Test: Add aqueous sodium hydroxide.  Result: turns damp red litmus paper blue.

7) b) i) Moles of Mg = 3/24 = 0.125
           Moles of CH3COOH = 12/60 = 0.200
           Using ratios given in the equation, to compare, divide 0.2/2 = 0.100 moles of CH3COOH.          
           Therefore, magnesium is in excess.

        ii) The one not in excess: ie. 0.1

        iii) 0.1*24 =2.4dm3

Got it?

--- End quote ---

Ya got it but q biii u didnt explain

6bi where is this kinda of test mentioned...????

thx a lot..

Ivo:

--- Quote from: gaurav95 on June 05, 2010, 03:43:20 pm ---Ya got it but q biii u didnt explain

6bi where is this kinda of test mentioned...????

thx a lot..

--- End quote ---

You mean 6) b) ii) or 7) b) ii)?

And the test for ammonium ions you just need to know.  Memorise them!

Navigation

[0] Message Index

[#] Next page

[*] Previous page