The Rate and Extent of Chemical Change Flashcards
How can you calculate the mean rate of reaction?
(amount of reactant used) / (time taken)
amount of product formed) / (time taken
How can the concentration of the reactant be calculated?
(amount - mol) / (volume of the reaction mixture - dm^2)
How might one measure the amount of reactants used if one of the products is a gas?
Measure the mass of the reaction mixture before and after the reaction takes place.
How might one measure the amount of product if the product is a gas?
Use a gas syringe and measure the time taken for the reaction to happen.
When do chemical reactions only occur?
When reacting particles collide with each other with sufficient energy.
What is activation energy?
The minimum amount of energy required to cause a reaction.
What factors affect the rate of reaction?
Temperature, concentration, surface area and catalysts,
On a graph showing the rate of reaction, what happens when the line falls flat?
One of the reactants has been used up.
How might one find the rate of reaction at a particular time on a rate of reaction graph?
By doing the tangent thing.
What is a catalyst?
A substance that increases the rate of chemical reaction without being used up in the process.
What does a catalyst do?
Reduces the amount of energy needed for a successful collision.
Provides a surface for molecules to attach to, which increases their chances of bumping into each eachother.
When do enzymes act as catalysts?
In biological systems.
What are examples of reactions that need different catalysts?
Cracking hydrocarbons uses broken pottery.
The manufacture of ammonia uses iron.
What happens in a reversible reaction?
The products can react to produce the original reactants.
What are examples of reversible reactions?
Solid ammonium chloride decomposes when heated to produce ammonia and hydrogen chloride. Ammonia reacts with hydrogen chloride gas to produce clouds of white ammonium chloride.
