Chemistry doubts..ask here!

[haochen]

ohhh a no.. to montenegro

 

[narutogirl]

hey urw ^_^
i have a question..so in nov 2010 v3
http://www.xtremepapers.me/CIE/Cambridge IGCSE/0620 - Chemistry/0620_w10_qp_63.pdf
number 5)d)i)
they asked about in iron(11)chloride in excess of aq. sodium hydroxide...i like usually said it forms an insoluble precipitate but in the m.s. they said i have to write green precipitate

so could anyone clarify that ^_^"

 

[Maleeha]

sorry i guess i didnt make myself clear enuf.. i meant the equation like i wrote in my test
2Fe(s) + 3/2O2(g) ----moisture---> Fe2O3(s)
but was marked zero..

 

[Maleeha]

and if pH of ammonia is given 11, does it mean it is weakly alkaline????

no 11 12 13 14 are consider as strong
1 2 3 are consider as strong acid
4 5 6 are consider as weak acid
7 is neutral
8 9 10 are consider as weak acid

hope u got it [/quote]

But my teacher marked it wrong
she encircled weak alkaline as correct... n i didnt remember to ask her again :%)

 

[haochen]

hey urw ^_^
i have a question..so in nov 2010 v3
http://www.xtremepapers.me/CIE/Cambridge IGCSE/0620 - Chemistry/0620_w10_qp_63.pdf
number 5)d)i)
they asked about in iron(11)chloride in excess of aq. sodium hydroxide...i like usually said it forms an insoluble precipitate but in the m.s. they said i have to write green precipitate

so could anyone clarify that ^_^"

this is a test for iron (11) so it doesnt dissolve in excess. (cation table)
and it give green ppt.

sorry i guess i didnt make myself clear enuf.. i meant the equation like i wrote in my test
2Fe(s) + 3/2O2(g) ----moisture---> Fe2O3(s)
but was marked zero..

u didnt write H2O which is a huge mistake coz water is always present in the product of rusting.
and i am not sure of the reactant
but i think its Fe + O2 + H2O

 

[haochen]

and if pH of ammonia is given 11, does it mean it is weakly alkaline????

no 11 12 13 14 are consider as strong
1 2 3 are consider as strong acid
4 5 6 are consider as weak acid
7 is neutral
8 9 10 are consider as weak acid

hope u got it

But my teacher marked it wrong
she encircled weak alkaline as correct... n i didnt remember to ask her again :%)[/quote]

no 11 is consider as strong !!!!
in my note it is written like this and in my book also so ill follow mine

 

[cHeStEr]

If a nail was put in 3 test tubes .. 1 distiller water . 2 tap water . 3 sea water
In which test tube would it rust more faster ?

 

[narutogirl]

and if pH of ammonia is given 11, does it mean it is weakly alkaline????

this is what written in my notes
strong acid: 0 1 2
weak acid : 3-6
neutral:7
weak alkaline: 8-11
strong acid: 13 14

so ya according to my notes it is a weak alkaline actually in my notes its written 8-9 is ammonia so :/

 

[Maleeha]

k thnx fer both the answers..

 

[cHeStEr]

and if pH of ammonia is given 11, does it mean it is weakly alkaline????

no 11 12 13 14 are consider as strong
1 2 3 are consider as strong acid
4 5 6 are consider as weak acid
7 is neutral
8 9 10 are consider as weak acid

hope u got it

But my teacher marked it wrong
she encircled weak alkaline as correct... n i didnt remember to ask her again :%)

no 11 is consider as strong !!!!
in my note it is written like this and in my book also so ill follow mine [/quote]
Strong acid 0-2 weak acid 3-6 neutral 7 weak base 8-11 strong base 12-14

 

[narutogirl]

hey urw ^_^
i have a question..so in nov 2010 v3
http://www.xtremepapers.me/CIE/Cambridge IGCSE/0620 - Chemistry/0620_w10_qp_63.pdf
number 5)d)i)
they asked about in iron(11)chloride in excess of aq. sodium hydroxide...i like usually said it forms an insoluble precipitate but in the m.s. they said i have to write green precipitate

so could anyone clarify that ^_^"

this is a test for iron (11) so it doesnt dissolve in excess. (cation table)
and it give green ppt.

so saying that it is insolube is not enuf..ok :/

 

[narutogirl]

If a nail was put in 3 test tubes .. 1 distiller water . 2 tap water . 3 sea water
In which test tube would it rust more faster ?

now i know about freshwater and sea water
for fastest its salt water since it has an ionizing effect that would ionize the water and make the rusting process faster

fresh water i guess is distilled water because distilled water is the water obtained after making distillation to sea water
so it would be slower
about tap water i am not sure

 

[cHeStEr]

If a nail was put in 3 test tubes .. 1 distiller water . 2 tap water . 3 sea water
In which test tube would it rust more faster ?

now i know about freshwater and sea water
for fastest its salt water since it has an ionizing effect that would ionize the water and make the rusting process faster

fresh water i guess is distilled water because distilled water is the water obtained after making distillation to sea water
so it would be slower
about tap water i am not sure

Okay thanks so much for sharing your views !
And about the tap water .. One of the XPF member said that .. The tap water would accelerate the process of rusting because of impurities present in it .. But I m not sure if he is correct !?! What do you think !??
And can you explain me the ionising effect to me please ! I have not learnt about it .. If you can .. Itll be rely kind of you !

 

[AStarHunter]

guyz, do we have to know the rusting formulae ?! and do we have to know moles for paper 6 ?

oh, i have another qs : in this paper : http://www.xtremepapers.me/CIE/Cambridg ... 8_qp_6.pdf ---> Q1(b)(ii)---->i labelled next to the dot- is that alright ? cause i didn`t really get the mark scheme ? :%) :shock:

 

[cHeStEr]

guyz, do we have to know the rusting formulae ?! and do we have to know moles for paper 6 ?

oh, i have another qs : in this paper : http://www.xtremepapers.me/CIE/Cambridg ... 8_qp_6.pdf ---> Q1(b)(ii)---->i labelled next to the dot- is that alright ? cause i didn`t really get the mark scheme ? :%) :shock:

No moles for p6 it's supplement and p6 is based on core curriculum !

 

[haochen]

If a nail was put in 3 test tubes .. 1 distiller water . 2 tap water . 3 sea water
In which test tube would it rust more faster ?

now i know about freshwater and sea water
for fastest its salt water since it has an ionizing effect that would ionize the water and make the rusting process faster

fresh water i guess is distilled water because distilled water is the water obtained after making distillation to sea water
so it would be slower
about tap water i am not sure

Okay thanks so much for sharing your views !
And about the tap water .. One of the XPF member said that .. The tap water would accelerate the process of rusting because of impurities present in it .. But I m not sure if he is correct !?! What do you think !??
And can you explain me the ionising effect to me please ! I have not learnt about it .. If you can .. Itll be rely kind of you !

he is wrong

and ionising effect??? never heard of them but if u gave me some example or question i might know

guyz, do we have to know the rusting formulae ?! and do we have to know moles for paper 6 ?

oh, i have another qs : in this paper : http://www.xtremepapers.me/CIE/Cambridg ... 8_qp_6.pdf ---> Q1(b)(ii)---->i labelled next to the dot- is that alright ? cause i didn`t really get the mark scheme ? :%) :shock:

they mean that it should be on the same line as the dot.
u r right

 

[cHeStEr]

Hey Haochen .. The ionising effect is a thing which even I dont know .. But narutogirl mentioned it in her previous post .. So I came up with that question .. Btw me too hearing it for the first time !

 

[haochen]

so could anyone clarify that ^_^"

this is a test for iron (11) so it doesnt dissolve in excess. (cation table)
and it give green ppt.
[/quote][/quote]

so saying that it is insolube is not enuf..ok :/[/quote]
saying insoluble is not enough coz u need to follow the test and write all the observation

Hey Haochen .. The ionising effect is a thing which even I dont know .. But narutogirl mentioned it in her previous post .. So I came up with that question .. Btw me too hearing it for the first time !

i think it means that the time taken to completely rust the iron

 

[cHeStEr]

Absolutely no clue .. Because .. Her line says .. Sea water has more ionising effect so it ionises water .. ??
No idea about it !

 

[haochen]

i think it means that the time taken to completely rust the iron