Have a few MCQ questions here that I can neither understand nor answer correctly:
1) Which of the salts below is best prepared by titration?
Ammonium chloride
Aluminium sulphate
Copper (II) nitrate
Silver iodide
Titration is used for soluble salts, so silver iodide is out. How do I choose the between the rest of the 3 options?
2) Which of the following chemicals could be used to distinguish between dilute sulphuric acid and dilute hydrochloric acid?
Aqueous ammonia
Barium nitrate
Copper (II) carbonate
Lead (II) nitrate
I originally chose lead nitrate because it would form lead sulphate (sparingly soluble) and lead chloride (insoluble), but it was wrong..
3) After acidification with dilute nitric acid, a colorless solution of J reacted with aqueous silver nitrate to give a white precipitate. What could J be?
Iron (II) chloride
Lead (II) chloride
Potassium carbonate
Hydrochloric acid
How to choose..silver when reacted with any of these 4 chemicals should give an insoluble salt.. >.<
Would appreciate any help!
1) Ammonium Hydroxide and Hydrochloric acid give you
2) How is the solubility of Barium Sulphate and Barium chloride? This is under chapter salt.
3) If you see anything react with nitrate, must assume is something carbonate. Silver carbonate is poorly soluble.
Originally posted by Darkness_hacker99:1) Ammonium Hydroxide and Hydrochloric acid give you
2) How is the solubility of Barium Sulphate and Barium chloride? This is under chapter salt.
3) If you see anything react with nitrate, must assume is something carbonate. Silver carbonate is poorly soluble.
1) Why can't we react say - aluminium nitrate and sulphuric acid?
2) Why should barium sulphate be chosen over lead nitrate? Barium sulphate is insoluble, barium chloride is soluble. Lead sulphate is insoluble but lead sulphate is soluble.
3) Can form silver chloride which has white ppt as well...
Ok, finally managed to work out the first 2 questions:
1) Titration is only for group 1/ ammonium salts (soluble ones)
2) Lead chloride/Lead sulphate are both insoluble. Barium sulphate is insoluble, barium chloride is soluble. So is barium the answer? What about ammonia?
3) Still don't understand. :P
Originally posted by donkhead333:1) Why can't we react say - aluminium nitrate and sulphuric acid?
2) Why should barium sulphate be chosen over lead nitrate? Barium sulphate is insoluble, barium chloride is soluble. Lead sulphate is insoluble but lead sulphate is soluble.
3) Can form silver chloride which has white ppt as well...
because u r so dead.
nitrate salt dun ract with acid !! at least under the syllabus.
qn3. lead chloride already insolulbe. qn say is SOLUTION.
c0ckeye. let me test u 1 more qn
tis is an eexperiment to determine at the number of valence electron that an element which in a reaction has .elment x react with chlorine to form gaseous compound xcl2 .what is electronic configuration of X when it reacts with chlorine gas to form compound xcl2 ?
a) 2,8,2
b) 2,6
c)2,5
d)2,8,1
So whats the answer for question 3..
BTW I say "O" level syllabus because it is part of it, but what I am learning currently is different from mainstream syllabus. So might be missing some components. i.e nitrate salts do not react with acids.
your question...no link with salt prept..but its A anyway
haha i think it' A too.
For question 3, I say the answer's Iron(II) Chloride. I don't think it's Potassium Carbonate because the dilute nitric acid should have reacted with the carbonate ion.
Why not hydrochloric acid though?
Still get silver chloride..
Oh ya, suddenly had a random question in mind.
In electrolytic half equations with chlorine gas being discharged, we write
2Cl- -2e- ->Cl2
Chlorine loses 2 electrons here..which isn't the case because chlorine gas is covalently bonded. So how does this "loss of electrons" occur at the anode?
And come to think about it..chlorine is commonly known with 7 valence electrons..but with reference to this equation
Cl- -2e- -> Cl
It has to lose 1 electron to form a complete shell instead of gaining one electron. I'm thinking that I missed out something big here..oxidation state or what not.
haha. all eye of prob xcl2 . GASEOUS.
rethink. =)
Originally posted by donkhead333:Oh ya, suddenly had a random question in mind.
In electrolytic half equations with chlorine gas being discharged, we write
2Cl- -2e- ->Cl2
Chlorine loses 2 electrons here..which isn't the case because chlorine gas is covalently bonded. So how does this "loss of electrons" occur at the anode?
And come to think about it..chlorine is commonly known with 7 valence electrons..but with reference to this equation
Cl- -2e- -> Cl
It has to lose 1 electron to form a complete shell instead of gaining one electron. I'm thinking that I missed out something big here..oxidation state or what not.
this i 1 dunoe. guess u really just have to remb that 2Cl- -2e- ->Cl2 lor .
Nvm.
Originally posted by yiha093:
tis is an eexperiment to determine at the number of valence electron that an element which in a reaction has .elment x react with chlorine to form gaseous compound xcl2 .what is electronic configuration of X when it reacts with chlorine gas to form compound xcl2 ?
a) 2,8,2
b) 2,6
c)2,5
d)2,8,1
This.
aw gaseous compound!! B...
i'm not sure for qn3 now..very sorry,
btw the eqn should be 2Cl- -> Cl2 + 2e
Originally posted by donkhead333:This.
gas. u got hear before 2,8,2, react with chlorine give u gasous ?
ionic compound leii ? perhaps u wrong due to diff syllabus ? they teach u ionic is gas eh ?
-_-
Nvm.
What about the 3rd question in the first post..?
Why not hydrochloric acid which will result in silver chloride, white ppt, as well?
uh.uh. wait.
how does acidified silver nitrate react with potassium carbonate give u silver chloride in the 1st place ?
u said that all 4 produces insoluble silver ppt.
enlighten me.
Originally posted by yiha093:uh.uh. wait.
how does acidified silver nitrate react with potassium carbonate give u silver chloride in the 1st place ?
u said that all 4 produces insoluble silver ppt.
enlighten me.
Fine. Error in my first post.
So why not hydrochloric acid???
Originally posted by donkhead333:Fine. Error in my first post.
So why not hydrochloric acid???
if potassium carbonate cant give u silver chloride then obviously hcl is the answer right? =.=
So the thing that causes hydrochloric acid to be a more suitable answer as compared to iron chloride would be the color..
Iron chloride is not colorless as I have found out for myself.
By the way, please try to be prompt in your answering...don't making people go round in circles when they are clearly seeking an answer instead of a counter-question.
Originally posted by donkhead333:So the thing that causes hydrochloric acid to be a more suitable answer as compared to iron chloride would be the color..
Iron chloride is not colorless as I have found out for myself.
yes . iron 2 is green. iron 3 is red.
question 3.. some ask why not HCl..
first under the chapter u learnt, acid reacts with what? bases, carbonates and metals.
is silver nitrate belonging to any category of these 3?
no, so HCl is out..
next, potassium carbonate, is a metal carbonate. so metal carbonate reacts with what? acid to give off CO2 and water and salt.... if u dunno then go study ur notes again...
so is silver nitrate an acid? no... so continue...
lead chloride, is already insoluble... question already said J is a solution...
now next, FeCl2, for 2 salts to react, is there such a reaction we learnt of? yes and it is precipitation... is FeCl2 soluble? yes, only lead and silver chloride is insoluble... so 2 solution add up to give off what? Fe(NO3)2 and silver chloride. so is iron nitrate soluble? yes cuz nitrates and soluble... and is silver chloride soluble? no, so ppt is formed...
therefore answer is iron chloride.
why hcl canot double displacement ma.
hcl + agno3 - > agcl + hno3
Please read up the purpose of acidification.
though not under 'O' level syllabus, acidification is actually a means of providing addition Hydrogens ion to the reaction.