3.2.3 Chemical equilibrium Flashcards
Define dynamic equilibrium
Where does this occur?
rate of forward reaction = rate of reverse reaction AND concentrations of reactants and products do not change
ONLY occurs in a closed system
What is the effect of concentration changes on equilibrium?
increased concentration of **product **= equilibrium shifts LEFT
increased concentration of **reactant **= equilibrium shifts RIGHT
What is the effect of pressure changes on equilibrium?
increased pressure = equilibrium shifts to the side with the **fewest moles **
decreased pressure = equilibrium shifts to the side with the **most moles **
changing pressure has NO IMPACT if moles are the same on both sides of the equation
What is the effect of temperature changes on equilibrium?
increased temp = shifts equilibrium in endothermic direction
decreased temp = shifts equilibrium in exothermic direction
What is the effect of a catlayst on equilibrium?
- DOES NOT shift the position of equilibrium
- system will reach equilibrium faster (lowers activation energy for both the forward and reverse reactions)
Why is compromise needed when considering the conditions for the haber process?
- low temp would produce a high yield BUT it would be very slow
- high pressure would produce a high yield and increased rate of reaction BUT would be expensive and dangerous
- so a moderate temp and pressure must be used
How does changing acid concentration impact the equilibrium between chromate ions and dichromate ions?
potassium chromate = yellow
- adding acid increased the hydrogen ion concentration
- equilibrium shifted right and solution became orange (as dichromate forms)
- adding aqueous sodium hydroxide decresed hydrogen ion concentration
- equilibrium shifted left and solution became yellow (as chromate forms)
What does a Kc value of 1 mean?
position of equilibrium is halfway between reactants and products
What does a Kc value greater than 1 mean?
position of equilibrium is shifted towards the products
What does a Kc value less than one mean?
position of equilibrium is shifted towards the reactants
