Rate of Reaction Flashcards
(19 cards)
What is the rate of a reaction?
How quickly the reactants turn into products.
How do you calculate the mean rate of reaction (reactant)?
Mean rate = quantity of reactant used / time taken
How do you calculate the mean rate of reaction (product)?
Mean rate = quantity of product formed / time taken
How is change in mass used to measure reaction rate?
Use a balance to measure mass loss as gas escapes. Rate = change in mass / time taken
What unit is used for rate from mass loss?
g/s (grams per second)
How is gas volume used to measure reaction rate?
Use a gas syringe or measuring cylinder. Rate = volume of gas produced / time taken
What unit is used for rate from gas volume?
cm³/s (cubic centimetres per second)
How is colour/turbidity used to measure reaction rate?
Time how long it takes for a cross under a flask to disappear as solution becomes cloudy
How can graphs be used to calculate rate?
The steeper the gradient, the faster the reaction. Shallow gradient = slower rate.
How do you find mean rate from a graph?
Mean rate = change in product or reactant / time between two points
What is collision theory?
Particles must collide with enough energy to react (activation energy)
What is activation energy?
The minimum energy needed for a reaction to occur
How can you increase the rate of reaction?
By increasing frequency and energy of collisions
How does temperature increase rate?
Particles move faster and collide more frequently with more energy
How does concentration increase rate?
More particles in same space = more frequent collisions
How does pressure increase rate (gases)?
More particles in a smaller volume = more collisions
How does surface area affect rate?
Smaller pieces = more area exposed = more frequent collisions
What are catalysts?
Substances that speed up reactions without being used up
How do catalysts work?
They provide an alternate pathway with lower activation energy
