acids and bases

homogenous equilibrium

contains equilibrium species that all have the same state or phase

heterogenous equilibrium

cotains equilibrium species that have diffrent states or phases

Kc equation

[concentration of products]/[concentration of reactants]

what species does Kc include

only includes species that are aqeouse or gaseouse

Kp constant

equilibrium constant in terms of partial pressure

mole fraction equation

No of moles/total No of moles in the gas mixture

partial pressure equation

mole fraction x total pressure

Kp equation

p(partial pressure of products)/p(partial pressure of reactants)

why do mole fractions work

Because under the same conditions of temperature and pressure the same volume of diffrent gases contains the same number of moles of gas molecules

K constant = 1

means the equilibrium is halfway between the reactants and products

K constant = very big

means the equilibrium is in favour of the products

K constant = very small

means the equilibrium is in favour of the reactants

when does K change

The equilbrium constant only changes when there’s a change in temperature. If there’s a change in concentratio or pressure the equilbrium constant value does not change

increasing the temprature effect on K

If the foward reaction is exothermic as the temperature increases the K value decreases so less products are formed. If the foward reaction is endothermic as the temperature increases the K value increases so more products are formed.

bronsted-lowrey acid

a proton donator

bronstwed-lowrey alkali

a proton acceptor

what is a conjugate acid-base pair

contains two species that can be interconverted by transfer of a proton e.g. HCl releases a proton to form its conjugate base Cl- and Cl- accepts a proton to form its conjugate acid HCl

monobasic

one proton can be replaced

dibasic

two protons can be replaced

tribasic

three protons can be replaced

Acid + metal

Acid + metal—> salt + hydrogen

Acid + carbonate

salt+H20+CO2

Acid + base

Acid + base —> salt + H20

base examples

metal oxide or hydroxide

pH<7

increasing acidity (gets more red)

pH>7

increasing alklainity (gets more blue)

equation for pH

-log([H+])

equation fro [H+] from pH

10^-pH

Calculating the pH of a strong acid

in aqeous solutions strong monobasic acids dissacociate completely so [HA]=[H+] so you can directly use pH equation

new concentration when the solution is diluted

(initial volume/new volume) x initila acid concentration

stron vs weak acid

weak acids only partially dissacociate wherease strong acids dissacociate fully

Ka expression

[H+][A-]/[HA]

pKa equation

-log(Ka)

Ka equation from pKa

10^-pKa

what does the size of the Ka value mean

the larger the Ka value the greater the dissacociation of the acid so the greater the acids strength resulting in a lower pKa value

approximations to use when finding the pH of a weak acid

[H+] = [A-] and that the concentration of HA doesn’t change. meaning that Ka= [H+]²/[HA]

what is Kw

the ionic product of water

equation for Kw

[H+] x [OH-]

numerical value of Kw at 298K

1 × 10^-14

what is meant by a ‘salt’

when the H+ in an acid is replaced by a metal ion