IB Chemistry


Acid deposition: 

To determine between a strong and weak acid put a piece of magnesium in the solution and see how fizzy it is, OR use electricity

pH = -log10[H+].         pOH= -log10[OH-]

whenever you see "p" in a question = (e.g) they ask you to work out pH always use -log10[H+]

Find the pH of 0.2M HNO3     = -log10(0.2) = 0.70

To work out the [H+] concentration when given pH...

use inverse of log = 10^ (-pH).      (e.g) HCl pH 0.02 -> 10^-0.02 = 0.95

REMEMBER if the H or OH is diprotic (has a 2 after it -(e.g) H2SO4) this means for every mole that is dissociated you get 2 H+ or OH- 

SO finding pH of 0.5M H2SO4 = -log10(1) = 0 { MULTIPLY the concentration BY 2 }

Finding [H+] ... (e.g) H2SO4 pH 0.8 -> 0.8= -log10(H+).   [H+]= 10^(-0.8) = 0.16.

{DIVIDE BY 2}  [H2SO4]= 0.08

Kw= ionic product of water = H2O<-> H+ + OH-  SO Kc= [H+][OH-]/ [H2O]

Kw at 25o = 1.0 x 10-14  pKw= -log10(Kw) = -log10(1.0 x 10-14)    


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