Chemistry sample paper corrections Flashcards
When calculating Kp, what is used as the units for partial pressure?
Pa or KPa, and you work out the units the same way as in Kc eg. for some it might be KPa-2
When it says draw a 3D diagram, what should you include?
The dotted/triangle shaped bonds and the lone pairs
When drawing the Boltzmann distribution, what should you do?
Always draw on Ea
In enthalpy calculations, what is really easy to forget?
The minus after working out /\H using Q
What is ionic compounds solubility?
Always soluble in water
When metals react with acids, what are the observations?
Effervescence and the metal dissolves
What is the difference between the lattice enthalpies of MgCl2 and CaCl2 and why?
The lattice enthalpy of MgCl2 is more exothermic
The ions have a smaller IONIC radius
There is a greater attraction between the Mg2+ and Cl- ions
What is the relative reactivity in halogens?
The trend is that the electron shielding increases down the group
Therefore the atomic radius increases
Therefore it is harder to gain an electron
They get less reactive as you go down the group
What is the colour of bromine water and bromine in organic solvent?
Yellow in bromine water
Orange in organic solvent
What is the steps of producing an acidic solution from solid acid?
Weigh the solid out
Dissolve the acid in a small amount of distilled water
Transfer the solution to a 250cm3 volumetric flask
Wash out the beaker so there’s no residue
Make the solution up to 250cm3 and invert to mix
In buffers, what do you have to do when the base is NaOH?
The moles of NaOH will be the same as the moles of [A-]
But is will react with the [HA] so take the moles of NaOH way from the moles of the acid
What would be the effect on the cell potential of increasing the concentration of something in an electrochemical cell?
It would shift the equilibrium away from that compound
Either more or less electrons will be released
So the cell potential will increase if more are e- are released
When are optical isomers formed in transition metal ions?
When there are bidentate ligands and it is an octahedral structure
What values can Kc be?
Any value
If above 1, it is to the right
If below 1, it is to the left
What is the charge on the chromium transition metal ion that is green?
+3
