Equilibria I & II Flashcards
Features of dynamic equilibrium
- the forward and backward reactions are still happening.
- the rates of the forward and backward reactions are the same.
- the concentrations of the reactants and products remain constant (they do not change)
- in a CLOSED system
Features of static equilibrium
- the forwards and backwards reactions have ceased
- in a CLOSED system
- no movement between products and reactants
what affects Kc value?
if the temperature changes once equilibrium has been reached
how can you tell whether a reaction’s equilibrium lies to the left or right based on its Kc value?
> 1 = lies to products (the fraction is top heavy)
<1 = lies to reactants (the fraction is bottom heavy)
what do [XXX] brackets mean?
Concentration of XXX
What is a proton?
a H+ ion
Acids are proton…
donors
Bases are proton…
acceptors
How do you mathematically define pH?
pH = -log10 [H+ (aq)]
What would be the [H+] in 1 mol dm^3 HCl
1 M
What would be the [H+] in 1 mol dm^3 H2SO4
2 M
What would be the [H+] in 1.5 mol dm^3 of HNO3
1.5 M
does water become more acidic or alkaline when heated? why?
eq. in H2O is
H2O = H+ + OH-
- forwards reaction is endo
- so eq. will shift to left to counteract heat increase
- so more H+ and OH- is made
- so [H+] increases, which will decrease the pH even though more OH- is made too
- because we only care about [H+] concentration
what is the the equilibrium constant for water and what is its value?
Kw
Kw = [H+(aq)][OH-(aq)]/ [H2O(l)]
so Kw = 1.0 x 10^-14 mol2 dm^-6
What do strong acids do in solution in water
Strong acids fully ionise to produce H+ ions when in solution in water
What do weak acids do in solution in water
Weak acids partially ionise to produce H+ ions in water
what is le chateliers principle
If a constraint is imposed upon a system, the system
will act to counteract that constraint.
what will happen if pressure is increased on this equilibrium?
CaF2 (s) + 2H (aq) + ⇌ Ca (aq)2+ 2HF (aq)
It is aqueous; pressure only affects gas
What will happen if I increase the concentrations of the constituents on the left of my equilibrium
EQ. will shift right
- to oppose the effect and counteract the change
What is the effect of catalysts on equilibrium?
- the position of equilibrium isn’t changed
- but the rate at which equilibrium is reached is quicker (increased)
what is the effect of increasing the temperature on an equilibrium when the backwards reaction is endothermic.
EQ. shifts to the left with the endothermic reaction
- because it wants to counteract the change and keep its original conditions (at equilibrium)
Give two characteristics of all reactions at
equilibrium.
- the [] of all reactants and products are the same
- the rate of the forwards reaction is equal to the backwards reactions
