6-The Rate and Extent of Chemical Change (2) Flashcards
What is a rate of chemical reaction?
How fast reactants are changed into products
How can you find the speed of rate of reaction?
Measuring quantity of reactants used up or produts formed over time
What is the calculation for mean rate of reaction?
mean ror = quantity of reactants used/time take
or
mean ror = quantity of products formed/time taken
What does a steeper line on a reaction time graph indicate?
Faster rate of reaction
What is the collision theory of reacting particles?
How often they collide
What is the quantity of reactant or product measured in?
mass in grams
volume in cm^3
What is required for successful collision?
Enough energy
What is activation energy?
The minimum amount of energy particles need to collide
Why is energy needed in reactions?
To break the bonds in the reactants and start the reaction
What is equilibrium in a reversible reaction?
The forward and backward reaction going at the same rate
Under what condition can equilibrium only be reached?
Within a closed system
What is true when equilibrium lies to the right?
The concentration of products is greater than reactants
What is true when equilibrium lies to the left?
The concentration of reactants is greater than products
What does the position of equilibrium depend on?
*Temperature
*Pressure
*Concentration
What is true about endo and exo reversible reactions?
If reaction is endothermic in one direction it is exothermic in the other direction
What is true about energy during endo and exo reversible reactions?
Energy transferred from surroundings by endo is equal to energy transferred to surroundings during exothermic
What is Le Chateliers Principle?
The idea that if you change the conditions of a reversible reaction at equilibrium, the system will try and counteract the change
What happens to equilibrium when temperature is decreased?
*Equilibrium move in the exothermic direction to produce more heat
*More products for the exothermic reaction and fewer for the endothermic
What happens to equilibrium when temperature is increased?
*Equilibrium move in the endothermic direction to try and decrease heat
*More products for the endothermic reaction and fewer for the exothermic
What happens to equilibrium when pressure is increased?
*Equilibrium tries to reduce and shifts to direction with fewer molecules of gas
What happens to equilibrium when pressure is decreased?
- Equilibrium tries to increase it and shifts to direction with more molecules of gas
What happens if you change concentration of reactants or products?
The system will no longer be at equilibrium
What happens if you increase conc of reactants?
More products formed to decrease it
What happens if you decrease conc of reactants?
More reactants formed to increase it
