UCAS Mock Flashcards
What is the volume of one mole of a gas?
24dm-3 or 24000cm-1
Calculate gas volume using moles
Volume = moles x 24
Avogadros constant
6.02 x 10^23
Ideal gas equation
pV = nRT
Units for ideal gas equation
p = Pa
V = m^3
T = Kelvin
Calculating mean titre things to remember
- only use concordant results (within 0.1cm^3 of each other)
- don’t include the rough titre
% yield
Actual / theoretical
Oxidation number of group1
+1
Oxidation number of group 2
+2
Oxidation number of group 7 ions
-1 if alone but can be variable
Oxidation number of oxygen
-2 unless in peroxide
Oxidation number of hydrogen
+1 unless in a metal hydride
Oxidation number of fluorine
ALWAYS -1
Energy change
q = mcΔT (in joules)
Test for carbonate ions
Add nitric acid
- if positive test, there’s effervescence as CO2 is produced
- test gas with lime water to confirm
Test for sulfate ions
Add aqueous barium chloride
- positive test: white precipitate formed (BaSO4)
Test for halides
Add aqueous silver nitrate
- positive test: precipitate formed
How to identify the precipitate formed in halide test
White - silver chloride
Cream - silver bromide
Yellow - silver iodide