Rates and Equilibria Flashcards
(32 cards)
What methods could we use to measure the rate of reaction?
1) Measure the change in mass
2) Time how long it takes for a colour change
3) Measure amount of product formed.
What equations do we use to calculate the rate of reaction?
1) Rate = Amount of Reactant Used / Time (s)
2) Rate = Amount of product formed / Time (s)
What units do we use for rate of reaction?
1) grams per second (g/s)
2) ml per second (ml/s)
3) cm3 per second (cm3/s)
4) Mol per second (mol/s)
How do you calculate the rate of reaction from a graph
By drawing a tangent at the point of the graph, find the gradient as gradient = rate of reaction
What is collision theory?
For a chemical reaction to take place, the reactants must first collide. For the collision to be effective the particles must have the right amount of activation energy.
What is activation energy?
The minimum amount of energy required for an effective collision.
Which factors affect the rate of reaction?
Concentration, Temperature, Catalysts, Surface Area and Pressure
How does increasing concentration affect rate of reaction?
More particles in the same area, so more frequent collisions, so increases rate of reaction.
How does increasing temperature affect rate of reaction?
Particles move faster as they gain more kinetic energy, so more likely to collide, so more likely to have the right activation energy, so increase rate.
How does adding a catalyst affect rate of reaction?
Reduces the activation energy, so less activation energy means more effective collisions, therfore faster rate.
How does increasing Surface Area affect rate of reaction?
More of the surface area is exposed and can collide, which means more effective collisions. So increase rate of reaction
How does increasing pressure affect rate of reaction?
Increasing pressure of gasses increases rate of reaction, particles are more squished together meaning more successful collisions.
Benefits of a Catalyst
1) Speeds up rate of reaction.
2) Not used up, so can be used again.
3) Only need a small amount.
4) Saves fuel cost.
Negatives of Catalyst
1) Can be expensive
2) One catalyst only works for a specific reaction
3) Will eventually need replacing
4) Eventually need to be removed from product at an extra cost.
What is a catalyst and how does it work?
A catalyst is a substance that changes the rate of reaction, without being used up. It offers an alternative pathway for a reaction with lower activation energy and so speeds up rate of reaction.
What is a reversible reaction?
They are reactions which the products react together to re make the reactants.
Example of a reversible reaction
Decomposition of Ammonium Chloride and change of anhydrous copper sulfate to hydrated copper sulfate
How does decomposition of ammonium chloride work?
When ammonium chloride is heated it decomposes to form ammonia and hydrogen chloride gas, as the gases rise and cool in the test tube, they reform ammonium chloride.
How can we show that some reactions are reversible (salts)
Salts that involve water or crystallisation take part in reversible reactions, e.g copper sulfate
What is dynamic equilibria?
The stage in a reversible reaction where the rate of the forward reaction is equal to the rate of the backwards reaction.
What do the amount of reactants and products depend on?
They depend on the condition of the reaction, concentration, temperature, etc.
What’s happen to an equilibrium if temperature increases?
Temperature - If we increase the temperature the equilibrium will shift to the endothermic position to reduce the temperature.
What happens to equilibrium if concentration is changed?
Equilibrium will shift to the reduce the side with the lower concentration.
What happens to equilibrium if pressure is increased?
If pressure is increased, equilibrium will shift to the side with the fewest molecules.
