Qualification > Sciences

CHEMISTRY DOUBT!!!

<< < (2/3) > >>

CHEMMASTER6000:

--- Quote from: cashem'up on June 09, 2010, 04:01:13 pm ---hey sorry for the first one i looked at the wrong ms but 2nd is still a doubt and one more doubt

In an experiment, 50.0 cm3 of a 0.10 mol dm–3 solution of a metallic salt reacted exactly with
25.0 cm3 of 0.10 mol dm–3 aqueous sodium sulphite.
The half-equation for oxidation of sulphite ion is shown below.
SO ? 2
3 (aq) + H2O(I) ? SO2?
4 (aq) + 2H+(aq) + 2e–
If the original oxidation number of the metal in the salt was +3, what would be the new oxidation
number of the metal?
A +1 B +2 C +4 D +5

Can someone please help and solve especially the great chemmaster thanx  :-[

--- End quote ---

hahaha yea i was pondering about your first question .

anyways i think your right with the word some it implys its MG because Al shows full covalent character this the acidic nature during hydrolysis.

hmm which question and which year is the 3rd question ?

cashem'up:
the answer is +2 and its either s07 or w07 chek it out most probably the 9th q

CHEMMASTER6000:
oh god yet another sneaky one. look at the oxygen number next to the sulphr it goes from so3 to s04. in old chemistry oxidatoin means gain in oxygen so sulphur gained oxygen which means the metal must have been reduce. since 1 o was gain, 1 reduction must be made thus 3+ to 2+

sizbeauty:
plz help me with these ques????
nov 09/variant12
Q9,20,22,27,40(plz tell me the logic behind the ans)
ppr is attachd..thankzz

CHEMMASTER6000:

--- Quote from: sizbeauty on June 09, 2010, 05:01:32 pm ---plz help me with these ques????
nov 09/variant12
Q9,20,22,27,40(plz tell me the logic behind the ans)
ppr is attachd..thankzz

--- End quote ---

9) in this particular question they make it confusing by putting the dissociation part. but if you look carefully PCL 5 forms PCL 3 and cl2. thus bond breaking which is always endothermic. the idea of the dissociation is that higher tempreture more energy provided more breaking bonds.
its phyrimidal because P is essentiall P4 but this is Pcl3 which means there is a lone electron and thus pushes the structure down wards forming the pyrimidal structure.

20)well in this case it says sis so the two r mus be on the same side. its 5 double bonds because in the ring it self there can only be 4 double bonds since the carbon on 1 point will have a hydrogen as well as be connected to the aliphatic chain . so it indicates there is 1 other doubhle bond in the aliphatic part fo total 5 bonds

22) well its not a and b since both does not form alchahol . d will make ketone which what you dont want. since any form of oxidation will effect at least 1 oh group . so 3 would be the most logicat one. you first polymerise it so you  break the double bond then you hydrolyse it which changes the halogenoalkane to alchahol.

27) ive answered this is one of the more recent threads. could you look ther eplease  ;D im very lazy to type it again ahahah

40)i have no exact explanation for this , the only thing i can dedue is well you wont form 1 mol from 1 mol. your adding more stuff so , it has to increase so if 1 is gone it can only be 2  or 3

Navigation

[0] Message Index

[#] Next page

[*] Previous page