How was 9701/33 chem praticals?

[ahmed butt]

i will lose marks in last question?,The first two was easy.

 

[Harsheys]

Hmm, I'm not too sure about the percentage purity of CaCl2
And the anion in FA5, does anyone know what it is?
I said CO3^2- because you can't add CuSO4 to a sulfate and get a precipitate, CO3^2- was the only other logical choice.

 

[awesomaholic101]

big mess

 

[ahmed butt]

Hmm, I'm not too sure about the percentage purity of CaCl2
And the anion in FA5, does anyone know what it is?
I said CO3^2- because you can't add CuSO4 to a sulfate and get a precipitate, CO3^2- was the only other logical choice.

i also co32- anion fa5

 

[ahmed butt]

Hmm, I'm not too sure about the percentage purity of CaCl2
And the anion in FA5, does anyone know what it is?
I said CO3^2- because you can't add CuSO4 to a sulfate and get a precipitate, CO3^2- was the only other logical choice.

what was your titre value

 

[awesomaholic101]

what was your titre value

24.90

 

[Harsheys]

what was your titre value

24.75
The supervisors was apparently 25.00

 

[darks]

ions:
co32-
so42-

mn2+
fe3+
nitrile
i think my 2nd one is wrong and so will be the equation then

 

[Harsheys]

ions:
co32-
so42-

mn2+
fe3+
nitrile
i think my 2nd one is wrong and so will be the equation then

No no, the ions in FA 6/7 were H+ ions

In FA5, it was CO3^2-
Hence your equation would be:
Cu^2+(aq) + CO3^2-(aq) => CuCO3(s)

In FA8 it was Mn^2+, Mg^2+ and CO3^2-

That's what I got anyways

 

[darks]

No no, the ions in FA 6/7 were H+ ions

In FA5, it was CO3^2-
Hence your equation would be:
Cu^2+(aq) + CO3^2-(aq) => CuCO3(s)

In FA8 it was Mn^2+, Mg^2+ and CO3^2-

That's what I got anyways

anyone confirm this ? FA8 ions look wrong...

 

[ahmed butt]

No no, the ions in FA 6/7 were H+ ions

In FA5, it was CO3^2-
Hence your equation would be:
Cu^2+(aq) + CO3^2-(aq) => CuCO3(s)

In FA8 it was Mn^2+, Mg^2+ and CO3^2-

That's what I got anyways

i think it was equation for sulphate ions not for carbonate ion

 

[ahmed butt]

anyone confirm this ? FA8 ions look wrong...

it is correct except the equation part its for sulfate so42- + Ba2+ =>BaSO4

 

[darks]

it is correct except the equation part its for sulfate so4- + Ba2+ =>BaSO4

But there was a brown gas formed... how can it be carbonate for FA8...
and a brown ppt too.
u didnt got a brown ppt?

 

[ahmed butt]

But there was a brown gas formed... how can it be carbonate for FA8...
and a brown ppt too.
u didnt got a brown ppt?

but for residue in first part there was fizzy reaction and gas realeased was co2

 

[darks]

but for residue in first part there was fizzy reaction and gas realeased was co2

ok and what about the brown ppt. why no fe3+ ?

 

[awesomaholic101]

I asked the instructor after exam what FA8 was ... she said cations are : Mn2+ and Mg2+ and anion is: either carbonate or sulphate (i.e, u get marks for both coz both were present)

 

[awesomaholic101]

but for residue in first part there was fizzy reaction and gas realeased was co2

wasnt it oxygen?

 

[darks]

I asked the instructor after exam what FA8 was ... she said cations are : Mn2+ and Mg2+ and anion is: either carbonate or sulphate (i.e, u get marks for both coz both were present)

wasnt it oxygen?

Did u get a brown ppt. ? anywhere? and how was mg2+ confirmed

 

[Harsheys]

Did u get a brown ppt. ? anywhere? and how was mg2+ confirmed

Not brown per se, but off white with the Manganate ion, which turns brown with addition of H2O2

Mg^2+ was confirmed by white ppt with NaOH, insoluble in excess. I had some time on my hands so I tested with NH3(aq), getting the same white ppt, insoluble in excess result.

And the gas with the residue + HNO3 was colorless, CO2, turned limewater milky if you tested it with a pipette and some limewater in a test tube. That's how I did all my CO2 tests

I did the same limewater test with the addition of H2SO4 with FA5, and got a positive result. That's how I reached the conclusion that the anion in FA5 was carbonate.

 

[manya]

what abt values of x and percentage loss