chemistry practical 32 discussion

[Enas Alhaje]

for the second experiment we all got from 35 to 45ish . that might explain the rate difference then . anyhow , if enough people got the same result then they'll accept your results . depends on the place you carried the experiment in too , as in its temperature .

 

[incorrectlytrue]

Is it just me or was the time a little bit insufficient? To carry out 6 experiments in question one alone, that's a lot! I got 1.67 somewhere I do remember that number. Was chlorine FB8?

I got 2 FB5's Hydrogen and Chromium I believe.. Or what was it.. Ahh I forgot! I think I the same no.s for Chlorine and Lead, that I'm sure about!

 

[asexamskillme111]

Is it just me or was the time a little bit insufficient? To carry out 6 experiments in question one alone, that's a lot! I got 1.67 somewhere I do remember that number. Was chlorine FB8?

I got 2 FB5's Hydrogen and Chromium I believe.. Or what was it.. Ahh I forgot! I think I the same no.s for Chlorine and Lead, that I'm sure about!

Lead Chloride is insoluble.

 

[anushey]

lol dude that's way too high..2000 mol.dm-3 per second?!
i doubt it. they even said we would have to use a value around 2.25 x10-3 if we don't get the answer. 0.0485 is way too high.
i think if we had to subtract it from something they would also tell us to use the information shown opposite along with use the answer in (iii)

i agree

 

[incorrectlytrue]

I got an increasing trend for the time, starting with 54 seconds. I think something was wrong with the ingredients' concentrations prepared at our laboratory prior to the exam..

 

[asexamskillme111]

wait how was the rate in thousands? if you divide 0.0485 or whatever you got by the time it would be a very small number?

 

[sarahnafea]

There's no other way to do it . I dont believe its wrong , because some people at my centre got the same answer. Anyhow , let's say its wrong , how many marks would I lose?

You're right actually. Lots of people got their rate in the 1000s. The teacher said it was right, but it confused alot of people as well.

 

[asexamskillme111]

You're right actually. Lots of people got their rate in the 1000s. The teacher said it was right, but it confused alot of people as well.

can you tell me what you calculated to get a rate that high? /:

 

[user]

What was you time for the first experiment? I got like 33 seconds.

i got 33 too

 

[Saad Sarfraz]

but i used that value to calculate rate of reaction for the graph...wouldn't my marks get deducted??

No that's the point in giving that value so that if u couldn't fo the first parts u can still do the rest accurately..if u know how to

 

[sarahnafea]

can you tell me what you calculated to get a rate that high? /:

I wish I knew the answer to that question. I too, could not make sense out of the 'decrease in concentration' question so I blindly used the value they gave. The people that did use their own value (that was correct) ended up with rates in the 1000s. The question specifically said, "You may use the value given, which is NOT correct." So you can't make estimates of your answer using a value that is incorrect in the first place. This is where most people went wrong.

 

[sarahnafea]

I got 33 too!

i got 33 too

 

[Enas Alhaje]

can you tell me what you calculated to get a rate that high? /:

0.048/time taken x 10^6 so it was something like 0.048/25 x 10^6 for the first one . Can anyone please tell me their percentage error? was it 0.25 or 0.5% ?

 

[Mclovin]

0.5%

 

[anushey]

omg i got the concentration as 1.67*10^3 and i used this to calculate my rate so how much marks will i lose...

 

[pearl angel]

No that's the point in giving that value so that if u couldn't fo the first parts u can still do the rest accurately..if u know how to

lol of course i do,thanx

 

[hmlahori]

does anyone remember which ions which solution contained. i think that was the only confusing part but rest was ok.

 

[vivo990]

does anyone remember which ions which solution contained. i think that was the only confusing part but rest was ok.

I have got:
FB5 is H2SO4
FB6 is CrO42-
FB7 is BaCl2
FB8 is Pb2+

Is that right???????

 

[vivo990]

wait how was the rate in thousands? if you divide 0.0485 or whatever you got by the time it would be a very small number?

because u multiply it by 10⁶/time taken

 

[user]

I have got:
FB5 is H2SO4
FB6 is CrO32-
FB7 is BaCl2
FB8 is Pb2+

yup thats correct...i got the same...