DN 5). Equilibria Flashcards Preview

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Flashcards in DN 5). Equilibria Deck (17):
1

equilibria is .... (4 conditions)

dynamic process
1). both reactions are taking place simultaneously
2). at the the same rate
3). all the reactants and products are present / closed system
4). all reactants and products concentrations remain the same / are constant

2

what is Le Chatelier's principle

if you apply a change to a system in equilibrium, the equilibrium shifts to oppose the change

3

explaining the change to equilibrium when
- temperature increase

state which reaction is exothermic
state what happens generically when temperature is increased: as temperature increases, equilibrium will shift to decrease the temperature therefore moves in endothermic direction
state what this means for the particular reaction (left or right hand shift)

4

explaining the change to equilibrium when
- pressure increases

state where there are more moles of gas
state what happens generically when pressure increases: as pressure increases, equilibrium moves to decrease the pressure by shifting to the side with the fewer moles
state what this means for the particular reaction

5

explaining the change to equilibrium when
- catalyst is added

alters the rate of the forward and backwards reaction by the same amount so equilibrium is reached faster
BUT EQUILIBRIUM WILL REMAIN IN THE SAME PLACE

6

equilibrium constants are ...measures

quantitative

7

homogeneous systems are where....

all species are in the same state

8

Kc =

[products] / [reactants]

9

how to work out units of Kc

moldm^-3 for each species then cancel accordingly

10

with Kc what happens to big numbers

they turn to indicies

11

Kc is ..... at constant temperature

constant

12

what happens when Kc is bigger than 1

more products than reactants

13

how to work out changing temperatures effect on Kc

draw table of temp vs Kc
as temp increases Kc ...... (if decrease then products are decreasing then vice versa)
therefore equilibrium has shifted to .... (use increase of heat = shift in endothermic direction to help work out)

14

concentrations effect on Kc

value of Kc will not change as is at a constant temperature
BUT [] will change individually

15

catalyst effect on Kc

no change to Kc (but will reach equilibrium faster)

16

how to calculate equilibrium constants with values

moles = conc / vol
replace [] with conc of the species (can often cancel out the volume as is based on total volume, not individual species volume

17

What is Kc?

A concentration