Equilibrium * Flashcards
What is a dynamic equilibrium?
when a reversible reaction is contained in a closed system and kept at a constant temperature it will eventually reach dynamic equilibrium
What is a reversible reaction?
a method of making a chemical product that keeps running without being stopped to remove the product
What is the activation energy?
the minimum amount of energy needed for a reaction to take place
What should you know about a reversible reaction?
reactants ⇌ products
the reactant is known as the LHS (left hand side)
the product is known as the RHS (right hand side)
the forward reaction goes from the LHS to the RHS
the reverse reaction goes from the RHS to the LHS
What is Le Chatelier’s principle?
if a dynamic equilibrium is disturbed by a change of conditions the equilibrium shifts to counter the change
What are three changes that might cause the equilibrium to shift?
- changing the concentration of the substances present
- changing the pressure of gases
- changing the temperature
What is the haber process?
What kind of reaction is this?
making ammonia by combining nitrogen gas with hydrogen
exothermic
What are the conditions needed for the haber process?
- 450 degrees
- 200 atmospheres of pressure
- an iron catalyst
The effect of temperature on equilibrium : Fill the gaps
if a _________ reaction is __________ in one direction it is __________ in the other direction
the same amount of ______ is transferred both ways
if a reversible reaction is exothermic in one direction it is endothermic in the other direction
the same amount of energy is transferred both ways
What is an exothermic reaction?
energy is transferred to the surroundings, so the temperature of the reactants will decrease
ΔH⚬ is negative
What is an endothermic reaction?
energy is absorbed from the surroundings by the reactants so the temperature of the reactants will decrease
ΔH⚬ is positive
What happens to the equilibrium if you increase the temperature?
the equilibrium moves to decrease the temperature so it moves in the endothermic direction
the relative amount of products increases for an endothermic reaction
What happens to the equilibrium if you decrease the temperature?
the equilibrium moves to increase the temperature so it moves in the exothermic direction
the relative amount of products at equilibrium increases for an exothermic reaction
What happens to the equilibrium if you increase the concentration?
If the concentration of one of the reactants (LHS) increases then the equilibrium would shift to the RHS to use more of the reactant (reduce the amount)
What happens to the equilibrium if you decrease the concentration?
if the concentration of one of the reactants (LHS) decreases then the equilibrium would shift to the LHS to make more of the reactant (increase the amount)
What happens to the equilibrium if you increase the pressure?
if the pressure increases the equilibrium will shift to decrease the pressure by moving to the side of the reaction with fewer moles of gas
e.g A + B ⇌ C so would shift to the RHS
What happens to the equilibrium if you decrease the pressure?
if the pressure decreases the equilibrium will shift to increase the pressure by moving to the side of the reaction with more moles of gas
e.g A + B ⇌ C so would shift to the LHS
How does a catalyst effect the equilibrium?
it increases the rate of both the forward and the reverse reactions equally
What are fertilisers?
ionic salts that contain ions like nitrogen, potassium and phosphorous
What kind of reaction is used to make fertilisers?
a neutralisation reaction as they are all salts
What are the neutralisation reactions for making salts?
metal + acid –> ?
base + acid –> ?
metal carbonate + acid –> ?
metal + acid –> salt + hydrogen
base + acid –> salt + water
metal carbonate + acid –> salt + water + carbon dioxide
How are ammonium salts made (in the lab)?
What colour is the indicator in the acid and alkali?
- carry out titration by filling the burette with acid and a conical flask underneath it with alkali and phenolphthalein indicator, add acid from the burette until the alkali in the flask is neutralised
- repeat this but by adding the indicator drop by drop
- add the neutral solution to a evaporating basin and evaporate some of the water by heating over a water bath
- leave in a warm place for 24 hrs to complete evaporation
colourless in acid, pink in alkali
