Rates Of Chemical Reactions and Equalibrium Flashcards
What is the ‘rate’ of a chemical reaction?
A measure of how quickly the reactants are converted into products.
What is the formula for calculating the rate of a chemical reaction?
rate = mass of product produced or lost ÷ time taken
or
rate = volume of product produced or lost ÷ time taken
What are the 3 different ways of measuring the rate of a reaction?
Precipitation and colour change.
Change in mass.
Volume of gas gained or lost.
How can precipitation and colour change be used to measure the rate of a reaction?
Precipitation - measure the time it takes for a mark (e.g black cross under flask) to disappear.
Colour change - measure the time it takes for a colour change to occur.
In both cases calculate the rate using: ‘1 ÷ time taken’.
What is the most accurate way to measure the rate of a reaction and why?
Change in mass, because the balance (scale) is the most accurate measuring device.
How can you use a gas syringe to measure the rate of a chemical reaction?
Use the gas syringe to monitor how the volume of gas changes over time.
Take measurements at regular intervals.
Plot your results on a graph.
Draw a tangent and calculate its gradient to find the rate at particular time.
What is a reversible reaction?
A reaction which can go both forwards and backwards
In terms of rate and concentration, During a reversible reaction, what happens as the reaction progresses and the reactants react?
The concentrations of reactants fall.
The forward reaction slows down.
The concentrations of products rise.
The backwards reaction speeds up.
When is a system ‘at equilibrium’?
When the rate of the forward reaction is equal to the rate of the backward reaction.
What is a dynamic equilibrium?
Where both the forward and backward reactions are happening, but there is no overall affect, because they are at the same rate - product is breaking down just as quickly as it is being formed, so there is no overall change in the concentrations of the reactants or products.
What condition is required for a reaction to reach equilibrium?
The reaction must take place in a closed system (where nothing can enter or leave).
What does it mean if the position of equilibrium lies to the right?
The concentration of the products is greater than the concentration of the reactants.
Does equilibrium mean the mass of products and reactants are equal?
NO! Their rates of reaction or equal
What 3 Factors affect equilibrium?
Pressure
Heat
Surface Area
How does a greater surface area affect equilibrium?
A powdered versions of a mass will react faster due to it having a greater surface area which causes more collisions
