EEE equations

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  • Created by: ava.scott
  • Created on: 13-01-15 15:33

Kc and Ka

Kc

Concentration of products/concentrations of reactants =Kc

moles go to the power of concentrations.

units vary, but if left at bottom of equation, they must be reversed.

Ka

Ka is the same, but ONLY looks at dissociation of 1 H+.

Therefore always:

HX + aq >>> H+ and X-

So units are always moldm-3

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pH and [H+] concentration

pH = -log[H+]

[H+] = 10^(-pH)

Strong acids fully dissociate, so the Concentration of [H+] is the same as the concentration of initial acid. So Concentration can be quickly substituted for [H+] in -log[H+]= pH

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Ka and Pka

Like pH is the log of [H+] concentration, pKa is the log of Ka (acid dissociation constant)

Ka= products/reactants

PKa= -log(Ka)

Ka = 10^(-pKa)

Weak acids do not fully dissociate, so you must work out Ka for the reaction. Concentration of the two products is the same so square the h+ concentration, and divide by the reactants e.g.

ka = [H+]^2 / [reactants]

If you are looking for H+ concentration, to find pH, you:

[H+] = square root (Ka x [reactants]

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enthalpy of neutralisation

Same as enthalpy of reaction, but ONLY for 1 mole of water.

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