AS Chemistry Practical - Paper 34

[Bluejeans#]

You will be having two different temperature readings.
One will be increasing, and one will either be decreasing or constant value.
Then you make a line through these 2 group of data, and the intersecting point between the lines (extended) will tell u temp. change and vol.

thankyouuu umm bt im still confused :/ two different temp reading ?

 

[@yeshaa]

You will be having two different temperature readings.
One will be increasing, and one will either be decreasing or constant value.
Then you make a line through these 2 group of data, and the intersecting point between the lines (extended) will tell u temp. change and vol.

what is the end point of methyl orange?

 

[mrnt3250]

what is the end point of methyl orange?

When it turns orange!!!

 

[Bluejeans#]

change of colour from golden yellow in alkaline solutions to pale permenant pink in acids ......erm i thnk so

 

[saadgujjar]

Salts coming are lead nitrite,zinc nitrate,carbonate and maganese

 

[Bluejeans#]

When it turns orange!!!

MARtin can u plz elaborate ?:/ that intersecting part

 

[ahmed abdulla]

its already orange ?
so how its

When it turns orange!!!

so how endpoind will be also orange

 

[mrnt3250]

MARtin can u plz elaborate ?:/ that intersecting part

When you make two straight lines, they go and go and go until they cross each other.
That point when they cross each other, from that they will ask u to look up temperature, and volume.
Just see what values it's pointing to.

 

[mrnt3250]

its already orange ?
so how its
so how endpoind will be also orange

In alkaline: Orange
In acid: Pink

 

[Bluejeans#]

When you make two straight lines, they go and go and go until they cross each other.
That point when they cross each other, from that they will ask u to look up temperature, and volume.
Just see what values it's pointing to.

i get the second part intersecting part bt Martin where to start dose two lines from :/

 

[ahmed abdulla]

In alkaline: Orange
In acid: Pink

now when do we have to stop adding acid ?? wat colour should it exacly be?
A pic will be a big help

 

[mrnt3250]

Salt Analysis for:
• Pb2+ (Lead):
o White ppt. soluble in excess of NaOH, but insoluble in excess of NH3.
o If you have a comparison between aluminium and lead, lead (II) ions are insoluble in dilute acids (add HCl to both solutions, ppt. remains the same if it’s Pb2+)
o Look at the reactions of anions, since Pb2+ (aq) is used as a test for Chromate, Cl – Br – I, Sulfate and Sulfite), you can understand its existence by reverse checking it.
• Mg2+ (Magnesium):
o White ppt. insoluble in excess of NaOH, and insoluble in excess of NH3.
• Fe2+ (Iron (II)):
o Green ppt. turning brown on contact with air, insoluble in excess of both NaOH and NH3
• Sulphate (SO4^-2):
o White ppt. with Ba2+ (Barium) or Lead (Pb2+) (insoluble in excess of HCl)
• Carbonate (CO3^2-):
o Effervescence of CO2 (which turns limewater cloudy) upon addition of dilute acid (HCl)
• Zinc (Zn2+):
o White ppt. soluble in excess of NaOH, and soluble in excess of NH3.
• Iodide (I-):
o Yellow ppt. with Ag2+ (insoluble in excess of NH3)
o Yellow ppt. with Pb2+
• Nitrate (NO3^-):
o NH3 released (which turns damp red litmus paper blue) on heating with NaOH and Aluminium foil.
• Nitrite (NO2^-):
o NH3 released (which turns damp red litmus paper blue) on heating with NaOH and Aluminium foil.
o NO released by adding HCl (colourless NO  (pale) brown NO2 in air)

 

[mrnt3250]

now when do we have to stop adding acid ?? wat colour should it exacly be?
A pic will be a big help

Dear, whenever there's an indicator, it usually has 2 colors and once they tell u to add, it has a color, and once u reach the end point it's color changes.
Simple common sense. No need of memorizing what colour.

 

[Bluejeans#]

Salt Analysis for:
• Pb2+ (Lead):
o White ppt. soluble in excess of NaOH, but insoluble in excess of NH3.
o If you have a comparison between aluminium and lead, lead (II) ions are insoluble in dilute acids (add HCl to both solutions, ppt. remains the same if it’s Pb2+)
o Look at the reactions of anions, since Pb2+ (aq) is used as a test for Chromate, Cl – Br – I, Sulfate and Sulfite), you can understand its existence by reverse checking it.
• Mg2+ (Magnesium):
o White ppt. insoluble in excess of NaOH, and insoluble in excess of NH3.
• Fe2+ (Iron (II)):
o Green ppt. turning brown on contact with air, insoluble in excess of both NaOH and NH3
• Sulphate (SO4^-2):
o White ppt. with Ba2+ (Barium) or Lead (Pb2+) (insoluble in excess of HCl)
• Carbonate (CO3^2-):
o Effervescence of CO2 (which turns limewater cloudy) upon addition of dilute acid (HCl)
• Zinc (Zn2+):
o White ppt. soluble in excess of NaOH, and soluble in excess of NH3.
• Iodide (I-):
o Yellow ppt. with Ag2+ (insoluble in excess of NH3)
o Yellow ppt. with Pb2+
• Nitrate (NO3^-):
o NH3 released (which turns damp red litmus paper blue) on heating with NaOH and Aluminium foil.
• Nitrite (NO2^-):
o NH3 released (which turns damp red litmus paper blue) on heating with NaOH and Aluminium foil.
o NO released by adding HCl (colourless NO  (pale) brown NO2 in air)

its given at the back of the paper ryt?

 

[mrnt3250]

its given at the back of the paper ryt?

Yes it is, just for revision

 

[mrnt3250]

Btw my name is not martin, but you can call me Flake

 

[Bluejeans#]

OKAY MARTIN FLAKE ......nw can u pleaseee explain me how to draw those two linesss Please

 

[abdullah100]

When you make two straight lines, they go and go and go until they cross each other.
That point when they cross each other, from that they will ask u to look up temperature, and volume.
Just see what values it's pointing to.

But wont we make the constant or decreasing gradient line from the same point i mean that point will be the intersection point obviously why will we extend?

 

[Buzzkiller]

You will be having two different temperature readings.
One will be increasing, and one will either be decreasing or constant value.
Then you make a line through these 2 group of data, and the intersecting point between the lines (extended) will tell u temp. change and vol.

Can you elaborate in which case will it(the line) become constant and when it will decrease?

 

[mrnt3250]

I guess a picture will say it all, just look:
http://img.ctrlv.in.s3.amazonaws.com/img/519d426bc59ba.jpg