Rates of Reaction Flashcards
How can the rate of a reaction be measured?
By the rate at which a reactant is used up, or the rate at which a reactant is formed.
What affects the rate of a reaction?
The temperature, concentration, pressure of reacting gases, surface area of reacting solids, and the use of catalysts.
When only can a chemical reaction happen?
If reactant particles collide with enough energy.
What are the two ways to measure a rate of reaction?
- Measure the rate at which a reactant is used up.
2. Measure the rate at which a product is formed.
What does the measurement of a reaction depend on?
The mass of a substance - solid, liquid or gas - is measured with a balance.
The volume of a gas is usually measured with a gas syringe, or sometimes an upside down measuring cylinder or burette.
What is the equation to work out the rate of reaction?
Amount of reactant used or amount of product formed divided by time taken.
How do you increase the rate of reaction?
The temperature is increased.
The concentration of a dissolved reactant is increased.
The pressure of a reacting gas is increased.
Solid reactants are broken into smaller pieces.
A catalyst is used.
What is the activation energy?
The minimum energy required for particles to react.
What happens if the concentration of a dissolved reactant or the pressure of reacting gas is increased?
There are more reactant particles in the same volume.
There is a greater chance of the particles colliding.
The rate of reaction increases.
What happens if a solid reactant is broken into small pieces or ground into a powder?
Its surface area is increased.
More particles are exposed to the other reactant.
There is a greater chance of the particles colliding.
The rate of reaction increases.
What happens if the temperature is increased?
The reactant particles move more quickly.
More particles have the activation energy or greater.
The particles collide more often, and more of the collisions result in a reaction.
The rate of reaction increases.
What effect does a catalyst have on the rate of reaction?
Catalysts increase the rate of reaction without being used up. They do this by lowering the activation energy needed. With a catalyst, more collisions result in a reaction, so the rate of reaction increases. Different reactions need different catalysts.
Catalysts are important in industry because they reduce costs.
