ANSWERING ALL BIO/CHEM PAPER 1 DOUBTS :)

[tornado]

i want to know the formula of the reaction of answer b (complete)

 

[Ahmed Khider]

hi friend

i want to know. is copper better to be the core or steel??

I think steel is better to be the core..I think but im nt sure i still didnt revise this chapter

 

[svenas]

wa eyyakum...
it's completely fine..juss remember me in your prayers

wat u thnk...is my suggestion ryt?

 

[сᴏᴏʟ сяуѕтᴀʟѕ]

98 nov q15...maybe A cauz it's still a solid (I mean not crushed ) so if the piece is smaller there will be less s.a, while when larger there will be more particles....maybe...
cauz they r talking only about the surface changing.....

the answer in the answer sheet is wrong for that! if there are smaller pieces of solid, the reaction will be fast..but i think in the answer sheet it's written D..right??

 

[princessanum]

i want to know the formula of the reaction of answer b (complete)

nh4oh + nacl
however, it further decomposes to create NH3(g)+H2O(l)+NaCl(aq)
so the full thing is
NaOH (aq) + NH4Cl (s) ---> NaCl (aq) + H2O (l) + NH3 (g)
And the ionic equation is
OH- (aq) + NH4Cl (s) ---> Cl- (aq) + H2O (l) + NH3 (g)

Hope it helps!

 

[svenas]

the answer in the answer sheet is wrong for that! if there are smaller pieces of solid, the reaction will be fast..but i think in the answer sheet it's written D..right??

yes u r ryt...I read it as piece not pieces!

 

[tornado]

the answer in the answer sheet is wrong for that! if there are smaller pieces of solid, the reaction will be fast..but i think in the answer sheet it's written D..right??

no c
you are correct

 

[Mozmozil]

Can u help me out with these... pretty pretty please..
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s07_qp_1.pdf
Question: 11 ..why is the answer B?

 

[svenas]

nh4oh + nacl
however, it further decomposes to create NH3(g)+H2O(l)+NaCl(aq)
so the full thing is
NaOH (aq) + NH4Cl (s) ---> NaCl (aq) + H2O (l) + NH3 (g)
And the ionic equation is
OH- (aq) + NH4Cl (s) ---> Cl- (aq) + H2O (l) + NH3 (g)

Hope it helps!

how do u know hw to write ionic equation plz explain me cauz I really don't know well...

 

[tornado]

nh4oh + nacl
however, it further decomposes to create NH3(g)+H2O(l)+NaCl(aq)
so the full thing is
NaOH (aq) + NH4Cl (s) ---> NaCl (aq) + H2O (l) + NH3 (g)
And the ionic equation is
OH- (aq) + NH4Cl (s) ---> Cl- (aq) + H2O (l) + NH3 (g)

Hope it helps!

yes thanks
but i don't understand the ionic equation

 

[thats_me]

need help with
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s11_qp_11.pdf q3 :S

 

[princessanum]

Can u help me out with these... pretty pretty please..
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s07_qp_1.pdf
Question: 11 ..why is the answer B?

The formulae for this acid is CH3COOH
It has8 atoms (4 x H, 2 x C, 2 x O),
Molecular mass= 60g/mole

 

[svenas]

the answer in the answer sheet is wrong for that! if there are smaller pieces of solid, the reaction will be fast..but i think in the answer sheet it's written D..right??

I need ur help hw 'princessanum' wrote ionic equation..can u plz help me before I close..

 

[сᴏᴏʟ сяуѕтᴀʟѕ]

no c
you are correct

no wait! the answer is C only...i didn't read the question properly..it's asking 'slower'!
if larger pieces (lumps) are there the reaction will be slow...but if smaller pieces (powder) are/is there..the reaction will be fast!

sorry my mind is in a complete mess right now....

 

[tornado]

need help with
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s11_qp_11.pdf q3 :S

ok.....
when the mixture was added to ethanol, their was still a residue, which means the mixture does not dissolve in ethanol (insoluble)
when added to water, the crystals was obtained from the filtrate so the mixture dissolved (soluble)

 

[tornado]

no wait! the answer is C only...i didn't read the question properly..it's asking 'slower'!
if larger pieces (lumps) are there the reaction will be slow...but if smaller pieces (powder) are/is there..the reaction will be fast!

sorry my mind is in a complete mess right now....

hhhhh

 

[tornado]

i think the answer is b??

 

[thats_me]

ok.....
when the mixture was added to ethanol, their was still a residue, which means the mixture does not dissolve in ethanol (insoluble)
when added to water, the crystals was obtained from the filtrate so the mixture dissolved (soluble)

umm which crystals? :\

 

[tornado]

umm which crystals? :\

the solid sorry

 

[princessanum]

I need ur help hw 'princessanum' wrote ionic equation..can u plz help me before I close..

sorry for the late reply,i was away....
the steps are:
Na+ OH- + NH4 Cl- = Na+ Cl- + H2O
OH- (aq) + NH4Cl (s) ---> Cl- (aq) + H2O (l) + NH3 (g)