Chemistry: Post your doubts here!

[Most_UniQue]

Yeah guys!!!!
Its paper 33!
I just dont now what went wrong!!?
I did exactly what the others did , but still ended up with this value!!
What might have went wrong!!
N whats the right answer!!!?

Which question? The titration one fr step 3? Tht depends on what ur mass of CaCo3 was , mine was 2.03g and titration values were around 19.4

 

[OmarALShamaa]

Yeah step 3!!!!

 

[OmarALShamaa]

hw come i got 4 for the titre value!!!!
Im sure i did it the right way!!!!
I mean ive been doing similar experiments through out the year and never got it wrong!!!

 

[Most_UniQue]

hw come i got 4 for the titre value!!!!
Im sure i did it the right way!!!!
I mean ive been doing similar experiments through out the year and never got it wrong!!!

I'm nt sure. Wt did ur friends get? My friends gt around 19 and some 20

 

[OmarALShamaa]

My friends got around 19 and 20 too!!!
But i revised the thing with them and we both did the exact thing!!!!!

 

[OmarALShamaa]

I also got one of the halides wrong!!!
I wrote Bromine instead of iodine!!!!
So im really worried I lose the A*!!!
=(

 

[OmarALShamaa]

*I mean A!!!!

 

[Most_UniQue]

*I mean A!!!!

Dude dont worry. The weighting of Practical paper is 20% so try to get good in your other paper.

 

[OmarALShamaa]

I did pretty good in paper 1!!!!
And , Ill try my best in paper 2!!!!!!

 

[JD REBORN]

In AS practical 33 what was the answer to the last part of the first question regarding using higher mass.Was it yes or no?
Secondly what was the answer to the question in wh0ich they asked us about the oxidation state?

 

[Most_UniQue]

In AS practical 33 what was the answer to the last part of the first question regarding using higher mass.Was it yes or no?
Secondly what was the answer to the question in wh0ich they asked us about the oxidation state?

I wrote it has no effect cuz its just a ratio. If mass increases , impurity also increases so their ratios will be same.

Their were 2 ox state questions , +2 and +4 I guess. I don't remember

 

[Henry930821]

for Paper 2 if the question asks for the reagent of oxidation, i wrote Potassium Manganate (VII) solution while the answer scheme gave Manganate (VII) ions. Are they both accepted? What should i write?

 

[Most_UniQue]

for Paper 2 if the question asks for the reagent of oxidation, i wrote Potassium Manganate (VII) solution while the answer scheme gave Manganate (VII) ions. Are they both accepted? What should i write?

Yah its accepted ...

 

[KurayamiKimmi]

does anyone remember thier value for percentage purity ?=O
(paper33)

 

[JD REBORN]

does anyone remember thier value for percentage purity ?=O
(paper33)

around 65 %

 

[KurayamiKimmi]

around 65 %

our values are close then coz i got 69-->rounded to 70

 

[oldfashionedgirl]

I got around 4cm3 for the second titration,
Any one got similar results!!!!!?

thats impossible :O 4 cm3??

 

[Most_UniQue]

does anyone remember thier value for percentage purity ?=O
(paper33)

I got 76%

 

[hmlahori]

People please help me here i dont get this one question from paper 2 seems quite simple

http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_s03_qp_2.pdf
http://www.xtremepapers.com/papers/.../Chemistry (9701)/9701_s03_ms_1+2+3+4+5+6.pdf
Q1 part C it says explain your answer. but i dont get the answer they gave in the mark scheme Why does the ratio have to be 3:1?

 

[Amy Bloom]

hello there.
Can anybody answer this:
A solution of vanadium (V) ions in 1 mol dm-3 H2SO4 slowly oxidises arsenic (III) oxide to arsenic (V) oxide according to the following (unbalanced) equation. Balance the equation.
As2O3 + VO2^+ + H+ ---> As2O5 + VO2+ + H2O