OCR F321 - 23rd May

Reply 380

Rickesh

I put that, but for 5 marks??

Reply 381

pink_floyd

8

Oh wait i think its because Oxygen is more electronegative.....but i didn't write that!

Reply 382

Rickesh

Original post by pink_floyd

Oh wait i think its because Oxygen is more electronegative.....but i didn't write that!

Yeah i put that ! Its more electronegative than nitrogen?

Reply 383

Moody

Where was the question about giant covalent structure? was it at the back as I didn't see it lol :L?

Reply 384

Killmepls

10

Original post by pink_floyd

Oh wait i think its because Oxygen is more electronegative.....but i didn't write that!

damn wish i thaught of that.. i wrote how h20 has more hydrogen bonds as there are more oxygens which have lone pairs. Ammonia only has one nitrogen with a lone pair for each three hydrogens.. lol what a fail

Reply 385

*QueenBeee

Original post by lil_kittie2

hey guys:

why was ammonia different boiling point to ice

what was the test for halide

why was there a difference between caco3 which was heated and the one which wasn't and was there similarity

what was the answer to 3s subshll

what was the sodium chlorate formula?? x

a) basically said the Oxygen in water molecule of ice has 2 lone pair e- and 2 hydrogen bonding for every water molecule and the nitrogen in ammonia had one lone pair so 1 hydrogen bond

b) test for halide i put add AgNO3 (aq) white precipitat should form and it will dissolve in dilute ammonia
Ag+ + Cl- >>>>AgCl (s)
could add bromine and iodine and no reaction should occur

c) similarity: gas given off
difference: solid formed in one other formed aqueous solution, one consisted of dissolving

d) 3s - 2

I think - some probz wrong - okkkish paper overalll
what did u put for last qu? xx

Reply 386

Solarity

5

Original post by lil_kittie2

hey guys:

why was ammonia different boiling point to ice

what was the test for halide

why was there a difference between caco3 which was heated and the one which wasn't and was there similarity

what was the answer to 3s subshll

what was the sodium chlorate formula?? x

Ammonia doesn't form as many interactions with other molecules as water does so there are weaker forces between the molecules, therefore less energy is needed to break molecules apart hence lower melting point.

Test for the halide was the AgNo3. Ag and CL would react to form a white precipitate. To make sure no other ions were present you react that with NH3 and it will completely dissolve (Bromine partially dissolves and Iodine it doesn't).

I said the similarity was that Co2 was released, wasn't 100% sure about the difference so i won't put it on here.

The 3s subshell is 2 electrons

I didn't get the sodium chlorate formula i don't think. I said (III) but fairly sure thats wrong.

Reply 387

Ttawwab

2

Original post by Solarity

I didn't get the sodium chlorate formula i don't think. I said (III) but fairly sure thats wrong.

I put (V), since the number in brackets afterwards is the oxidation number, isn't it? And I worked it out as 5, but who knows? :\

Reply 388

bagga

what was the test for halide

i put AgN03 , white preciptiate and ionic equation.

but instead of adding Br2 and I2 to see if reaction happens, i said add "cyclohexane", a different solvent and see if any other halides presesnt

???

Reply 389

lil_kittie2

Original post by Ttawwab

I put (V), since the number in brackets afterwards is the oxidation number, isn't it? And I worked it out as 5, but who knows? :\

what did you get for the percentage mass of a substance...

everyone i know got 93.3% but i got 87 % :s-smilie:

Reply 390

Solarity

5

Original post by Ttawwab

I put (V), since the number in brackets afterwards is the oxidation number, isn't it? And I worked it out as 5, but who knows? :\

Yeah that is the oxidation number but i was pretty clueless when it came to oxidation numbers for some reason. They have always been a bitch for me i worked hard on them but the question really wasn't nice.

Reply 391

*QueenBeee

Original post by Solarity

Ammonia doesn't form as many interactions with other molecules as water does so there are weaker forces between the molecules, therefore less energy is needed to break molecules apart hence lower melting point.

Test for the halide was the AgNo3. Ag and CL would react to form a white precipitate. To make sure no other ions were present you react that with NH3 and it will completely dissolve (Bromine partially dissolves and Iodine it doesn't).

I said the similarity was that Co2 was released, wasn't 100% sure about the difference so i won't put it on here.

The 3s subshell is 2 electrons

I didn't get the sodium chlorate formula i don't think. I said (III) but fairly sure thats wrong.

i put sodium chlorate (V) represents ox no of cl
what did u put for last qu??

Reply 392

YingYang

Original post by *QueenBeee

a) basically said the Oxygen in water molecule of ice has 2 lone pair e- and 2 hydrogen bonding for every water molecule and the nitrogen in ammonia had one lone pair so 1 hydrogen bond

b) test for halide i put add AgNO3 (aq) white precipitat should form and it will dissolve in dilute ammonia
Ag+ + Cl- >>>>AgCl (s)
could add bromine and iodine and no reaction should occur

c) similarity: gas given off
difference: solid formed in one other formed aqueous solution, one consisted of dissolving

d) 3s - 2

I think - some probz wrong - okkkish paper overalll
what did u put for last qu? xx

Difference was actually gas was given off, as

MgO + Hcl
MgCO3 + HCl

Similarity was they both dissolved. I think so, I reread the question to make sure.

Also was it Zn2(PO4)2?

Reply 393

Solarity

5

Original post by bagga

what was the test for halide

i put AgN03 , white preciptiate and ionic equation.

but instead of adding Br2 and I2 to see if reaction happens, i said add "cyclohexane", a different solvent and see if any other halides presesnt

???

No reaction would occur because Br2 and I2 are less reactive so wouldn't displace the chlorine. I think it was the use of NH3 because unless it was all CL- ions it wouldn't completely dissolve so you would see a precipitate from Br and I being present.

Reply 394

lil_kittie2

Original post by YingYang

Difference was actually gas was given off, as

MgO + Hcl
MgCO3 + HCl

Similarity was they both dissolved. I think so, I reread the question to make sure.

Also was it Zn2(PO4)2?

i just got ZnPO4 but i was too lazy to check if the equation balances :frown:

Reply 395

786girl

what were the changes in oxidation number of Na????

Reply 396

egypt305

The annoying thing was i totally forgot about adding silver nitrate, i just wrote add iodine and bromine and no reaction would occur and then add cyclohexane and it will stay orange :/ peak