chemical changes and structure and rates of reaction Flashcards
Explain the collision theory.
For a reaction to occur the reactant particles must come into contact, or collide with each other. The more collisions that occur, in a given time, the faster the reaction.
When there is low temperature, what is the rate of reaction like ?
The particles are moving slowly, resulting in very few collisions in a given time. The reactions is slow.
When there is a high temperature, what is the rate of reaction like?
The particles are moving quickly, resulting in many collisions in given time.The reaction is fast.
why do substances move about faster when they are heated?
They have more kinetic energy.
What is the concentration of a solution?
The measure of the number of particles of a solute in a given volume of solvent.
What does the word “mole” mean?
The measure of the number of particles of a substance there are.
When there is a dilute solution (low concentration) , what is the rate of reaction like?
There are a small number of moles of solute in a certain volume of solvent.This results in very few collisions and the reaction is slow.
When there is a concentrated solution (high concentration) , what is the rate of reaction like?
There are a greater number of moles of solute in the same volume of solvent. This results in more collisions and the reaction is fast.
Why does particle size/surface area have an effect on the rate of reaction?
when a solid reacts, it is only the particles on the surface area of the solid which come into contact with the other reactant.
what is the rate of reaction like when there is a large particle size?
The large particle size has a small surface area and limited contact with the other reactant. Therefore few collisions take place between the two reactants and the reaction is slow.
What is the rate of reaction like when there is a small particle size?
The small particle area has a large surface area and much greater contact with the other reactant.Therefore many collisions take place between the two reactants and the reaction is fast
What are the two ways you can monitor the rate of a chemical reaction?
By the change of mass and the change of volume of gas.
When is the concentration of reactants the highest?
At the start.
Why does the concentration of reactants decrease with time?
The reactants are being used up.
What does the gradient of the curve mean?
The slope of the curve.