Rate and Extent of Chemical Change Flashcards
Disappearance of cross practical?
Take a piece of paper and mark a cross on it.
Put the reaction flask on the cross.
Mix the reagents and measure how long it takes for the cloudy mixture to conceal the cross.
5 factors affecting the rate of a chemical reaction?
Concentration of reactants.
Pressure of gases.
Surface area.
Temperature.
Catalysts.
What is the collision theory?
Chemical reactions can only occur when reacting particles collide with each other with sufficient energy (more than or equal to activation energy)
What is the effect of increasing temperature on the rate of reaction?
When temp increase, ror increases.
As temp increases, the kinetic energy of the particles also increases so there are more energetic collisions.
Also, they move faster so there are going to be more collisions.
However temperature and rate of reaction are not directly proportional to one another.
What is the effect of increasing concentration on the rate of reaction?
When concentration increase, ror increases.
More reactants means faster collisions.
What is the effect of increasing pressure of gas on the rate of reaction?
It is basically the same as increasing concentration. It increases the number of gas molecules in the same volume so increases the frequency of the collisions and therefore increases the ror. Volume and pressure are inversely proportional to one another.
What is the effect of increasing surface area on the rate of reaction?
If the solid reactants are smaller pieces, they have a greater surface area. Increasing the surface area of solid reactants increases the frequency of collisions so it increases the rate of reaction.
What is an enzyme?
A molecule that acts as a catalyst in a biological system.
What is a reversible reaction?
When the products of a reaction can react backwards to produce the original reactants.
When is dynamic equilibrium reached?
In a closed system, when the forward and reverse reactions occur at the same rate and the concentrations of reactants and products remain constant.
What is Le Chatelier’s Principle?
If a system is at equilibrium and a change is made to any of the conditions, the system responds to counteract the change and restore the equilibrium.
