Chemistry Flashcards
What is the rate of a reaction?
how quickly reactants are used up or products are produced
What is the equation for calculating the mean rate of reaction?
mean rate = change in quantity of product or reactant / time taken
What is the unit for rate of reaction in a reaction involving a change in mass?
g/s
What is the unit for rate of reaction in a reaction involving a change in volume?
cm³/s
What is the activation energy?
the minimum amount of energy colliding particles have to have before a reaction will take place
What effect does increasing concentration have on the rate of reaction?
increases
Why does increasing concentration have this effect?
more reactant particles in the same volume lead to more frequent collisions
What effect does increasing pressure have on the rate of reaction?
increases
Why does increasing pressure have this effect?
less space between particles means more frequent collisions
What effect does increasing surface area have on the rate of reaction?
increases
Why does increasing surface area have this effect?
more reactant particles are exposed and able to collide, leading to more frequent collisions
What effect does increasing temperature have on the rate of reaction?
increases
Why does increasing temperature have this effect?
particles move faster, leading to more frequent collisions - particles have the same activation energy, so more collisions result in a reaction
What is a catalyst?
a substance that increases the rate of a reaction but is not used up in the reaction
How do catalysts increase the rate of a reaction?
lower the activation energy of the reaction, so more collisions result in a reaction
What is the Rate of Reaction?
The speed at which a reaction takes place.
How can the rate of reaction be measured?
By measuring how quickly the reactants are used up or how quickly the products are formed.
What are the three main methods to measure the rate of reaction?
- Change in mass
- Volume of gas formed
- Formation of a precipitate
Describe the method of measuring the rate of reaction by change in mass.
The mass of the flask and contents decreases as the gas formed leaves the flask.
How is the volume of gas formed used to measure the rate of reaction?
A gas syringe is used to collect the gas produced during the reaction.
What indicates the formation of a precipitate in a reaction?
The solution turns milky/cloudy as the precipitate is produced.
What is Collision Theory?
For a reaction to happen, the reacting particles must successfully collide.
What is required for a successful collision according to Collision Theory?
The reacting particles must have sufficient energy.
What is activation energy?
The minimum energy reacting particles must have when they collide for the reaction to take place.
