Practical + Mole Concept Flashcards
Solid/residue is yellow when hot, white when cold. What compound could it be?
ZnO
Any Zn compound.
What is the observation for sulfur dioxide gas?
Pungent gas turns purple acidified KMnO4 (aq) colourless.
What are some common complexes formed with excess ammonia during test for cations?
Cu[(NH3)4] 2+, Zn[(NH3)4] 2+
What are some common complexes formed with excess NaOH during test for cations?
Al[(OH)4]-, Cr[(OH)6]3-, Pb[(OH)4]2-, Zn[(OH)4]2-
What is the colour of Al(OH)3 ppt?
white!
What is the colour of Fe(OH)3 ppt?
red-brown!
What is the colour of Cr(OH)3 ppt?
green!
What is copper(II) sulfate used to test for? State the positive observation.
I- ions.
Obs: white ppt in brown solution formed.
(prdts: CuI (s) in aqueous iodine)
In a titration involving acidified KMnO4, why is it unnecessary to measure the volume of the sulfuric acid more accurately than by using a measuring cylinder?
Sulfuric acid merely provides an acidic medium for the titration, and it is also used in excess.
Hence, the exact amount of acid is not important.
In a titration involving acidified KMnO4, explain how the titre would be affected if hydrochloric acid was used instead of sulfuric acid.
HCl will be oxidised by KMnO4 to give chlorine gas, hence the no. of moles of KMnO4 required will be greater and this results in a larger volume of titrant, hence larger titre value.
What are the steps to prepare a standard solution?
https://drive.google.com/file/d/1IRbVUTrsBwtqcSxe3THRGSPFvkOokzoQ/view?t=150s
Relative formula mass is the same as relative molecular mass. T/F?
Relative molecular mass only applies to a covalent compound, while relative formula mass is for an ionic compound.
What is the equation for the reaction between iodine and thiosulfate? (should at least know the mole ratio between iodine and S2O3 2-)
iodine : thiosulfate = 1:2
What do I keep forgetting to include in my calculation of enthalpy change?
the +/- sign
