Chemistry Paper 61

[Z.A.M]

ummm... wadya mean "den"?

ummm... wadya mean "den"?

Oh dude wen this stuff was happening I wasn't online here

 

[ThatReallyReallyWeirdDude]

So wats the rite answer ThatReallyReallyWeirdDude

Sorry, but to which question?

 

[Z.A.M]

Sorry, but to which question?

The potassium bromide one the diff and that iron sulfate one

 

[Haseeb Ashraf]

lol the second graph was something like -/ right at the top

intersecting graph is basically like _
/
with the two lines conncted it was sorta easy....

i got the same !

 

[Beedo]

1-What if I wrote:
a-no more dissolving of iron
b-no more gas evolving instead of no more effervesence or bubbles (is that considered right?)

2-If I did the connection between the 2 straight lines in the graph wrongly but the points are right how many marks will that cost & will they consider it wrong if I got a wrong point for 3.5 but it was depending on my graph

3-What is amount of heat produced by pentanol ( I wrote 45)

4-what can be done to increase rate of reaction at step 2?

I really did so bad,thought that people would be saying that it was hard not easy

 

[ThatReallyReallyWeirdDude]

The potassium bromide one the diff and that iron sulfate one

First of all I'm pretty sure it's Potassium Chloride
Not sure what you mean by the 'diff'

Here goes:
Iron Sulfate one: What I wrote (and don't take this as law, but if you think from your knowledge it sounds correct)...The iron sulphate is in a solution, so when you boil it for several minutes the water will evaporate, creating a saturated solution. Further boiling will cause crystals of hydrated iron sulphate to form (since the volume of water can't hold it)
Potassium Chloride:
It was either a displacement or a precipitation reaction, the reason the height of the last two results was the same is because when 6cm3 of KCl is added, all the Pb(NO3)2 is used up; therefore, past 6cm3, the Pb(NO3)2 becomes the limiting factor. The next question basically had same answer (what would happen if you added 7,8,9,10 cm3 of KCl - the Pb(NO3)2 is the limiting factor etc.)
As for what would happen if you used AgNO3 instead of PbNO3, I wrote that you'd reach the limit after adding 3cm3 of KCl instead of 6cm3, because if you look at equations when using lead the mole ratio of KCl: PbNO3 is 2:1, but for silver KCl:AgNO3 is 1:1 - thus to react with the same 3cm3 of AgNO3 you need half the amount of KCl than you neededf for Pb

 

[ThatReallyReallyWeirdDude]

1-What if I wrote:
a-no more dissolving of iron
b-no more gas evolving instead of no more effervesence or bubbles (is that considered right?)

2-If I did the connection between the 2 straight lines in the graph wrongly but the points are right how many marks will that cost & will they consider it wrong if I got a wrong point for 3.5 but it was depending on my graph

3-What is amount of heat produced by pentanol ( I wrote 45)

4-what can be done to increase rate of reaction at step 2?

1- your answer is correct
2-I think there's error carried forward if you drew the graph wrong. I'd guess you lose 1-2 marks, but not sure.
3-I got 44 for this but they usually have a plus-or-minus-1 type thing, i.e. a range for the answer
4-stirring. Some people here say heating is also correct but since they said the water added is hot, then stirring is the safe answer.

 

[jasmineRocks]

Oh ryt...sry i was toking abt the other graph then...u have to exclude a point in tht ryt?!...
IA we'll pass wid A*'s...x)

Nshallah I hope so..

 

[Z.A.M]

@That really weird dude I was only asking about the silver nitrate not the whole question one it was for one mark dude I don't think it required the mole thingy y cudnt it be yellow ppt formed

 

[IGCSE O/L student]

ummm... wadya mean "den"?

da guy ws commentin on evy1's ans, n u knw ws sort of diggin out da faults. so i kinda got mad, n scolded him. but den sum really nyc person calmed me dwn, n xplained wat da guy ws actually doin. so i apologised 4 my bad behaviour!

 

[ThatReallyReallyWeirdDude]

@That really weird dude I was only asking about the silver nitrate not the whole question one it was for one mark dude I don't think it required the mole thingy y cudnt it be yellow ppt formed

Yeah it's only one mark
I just wrote that limit is at 3cm3
I didn't explain the mole thing
And second, it's potassium chloride. Both Lead Chloride and Silver Chloride are white.

 

[Z.A.M]

da guy ws commentin on evy1's ans, n u knw ws sort of diggin out da faults. so i kinda got mad, n scolded him. but den sum really nyc person calmed me dwn, n xplained wat da guy ws actually doin. so i apologised 4 my bad behaviour!

Well apologizing always makes a bigger person

 

[jasmineRocks]

what happens when silver nitrate reacts with the aqueous potassium??
and why were the height same for the soliudd?

the heights where the same because only 3cm of aqueous lead nitrate was added to all the experiments

 

[Z.A.M]

Yeah it's only one mark
I just wrote that limit is at 3cm3
I didn't explain the mole thing
And second, it's potassium chloride. Both Lead Chloride and Silver Chloride are white.

But the salt forming was silver iodide I'm talking about the second last part dude

 

[jasmineRocks]

the heights where the same because only 3cm of aqueous lead nitrate was added to all the experiments

and a white ppt will form i guess...

 

[Beedo]

What about the adding more KCl 2 question .. I don,t remember them very well

 

[thats_me]

What about the adding more KCl 2 question .. I don,t remember them very well

it will remain the same

 

[jasmineRocks]

What about the adding more KCl 2 question .. I don,t remember them very well

what about it wt weren't u able to solve in it?

 

[Z.A.M]

it will remain the same

That's rite

 

[ThatReallyReallyWeirdDude]

Yeah it's only one mark
I just wrote that limit is at 3cm3
I didn't explain the mole thing
And second, it's potassium chloride. Both Lead Chloride and Silver Chloride are white.

ALRIGHT THEN
I just called a friend
It was IODIDE
But even then, silver iodide and lead iodide are broth bright yellow
Whatever imma go study physics, no need to dwell on whats over