Chemistry - Rate and Extent of Change of Energy
- Created by: 15rolletta
- Created on: 23-06-17 19:26
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- Rate and Extent of Change of Energy
- The rate of a reaction is the amount of product formed / reactant used, over time
- You can show this with a graph, product formed on y and time on x
- The steeper the line, the faster the rate of reaction
- When the line goes flat, the reaction has ended
- Mean rate of whole reaction: overall change on the y, divided by total time
- The rate of a specific point can calculated with the gradient of a tangent
- The steeper the line, the faster the rate of reaction
- The time can be measure by visual means
- The produce can be measure by a change in mass (gas given of)
- It can also be measure by the volume of gas given of, via syringe
- You can show this with a graph, product formed on y and time on x
- Collision Theory
- The more collisions between reactants, the faster the reaction
- Particles must collide with enough energy
- Factors which affect the rate of reaction
- Temperature: the faster moving particles will collide more, and with more energy
- Concentration/pressure: there are more particles in a given area, so more collisions
- Surface Area: for the same volume of solid, the reactants will have more room to work on, increasing collisions
- Catalysts: they decrease activation energy by providing an alternate reaction pathway
- Reversible Reactions
- As the reactants react, their concentration falls, slowing t he forward reaction
- As more products are formed and their concentrations rise the backward reaction will speed up
- This continues until forward and backward reactions are going at the same rate, equilibrium
- This only happens in a closed system
- This continues until forward and backward reactions are going at the same rate, equilibrium
- As more products are formed and their concentrations rise the backward reaction will speed up
- Equilibrium
- This continues until forward and backward reactions are going at the same rate, equilibrium
- This only happens in a closed system
- If the equilibrium lies to the right, the concentration of the products is greater (and vice versa)
- The reaction can be endothermic one way and exothermic the other
- This continues until forward and backward reactions are going at the same rate, equilibrium
- Le Chatelier's Principle
- If you change the conditions, the system will try to counter act that change
- If you add heat, the equilibrium will move in the endothermic direction to absorb heat making more endothermic products (and vice versa)
- If you increase the pressure in gasses, the equilibrium will move to the direction where there is fewer moles (and vice versa)
- If you increase the concentration of reactants, the system tries to decrease it by making more products ((and visa versa(and visa versa))
- If you change the conditions, the system will try to counter act that change
- As the reactants react, their concentration falls, slowing t he forward reaction
- The rate of a reaction is the amount of product formed / reactant used, over time
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