Controlling the rate of reaction 1 and 2 Flashcards
What can affect the rate of chemical reaction
- concentration of reactants
- pressure (gas reactions)
- particle size
- temperature
- collision geometry
Simple collision theory states …
that for reactants to form products they must first collide with the correct collision geometry and correct energy
How does Concentration affect reaction rate and why?
The higher the concentration of the acid the faster the reaction
The more particles, the more collisions, and so greater chance of reaction and products being formed and therefore greater relative rate
How does Pressure affect reaction rate and why?
Higher pressure faster rate
The gas molecules are being compressed into a smaller space increasing the likelihood of successful collision and thus increasing rate
How does Particle size affect reaction rate and why?
Smaller particle size, faster reaction
Smaller particles means greater surface are on which collisions and so reactions can occur. Therefore increaszed rate
How does Temp affect reaction rate and why?
Higher temp, fatser reaction
Temperature increase means that reactant particles will have a greater kinetic energy. In order for successful reaction to occur the reactants must have the same or more energy than the activation energy.
As more particles are at or above activation energy more collisions occur at greater speed and energy and so more success and thus greater rate
Temperature is a measure of
the average kinetic energy of the particles in a substance
What is the relationship between reaction time and relative rate
the rate of reaction is inversely proportional to time, so can be taken as he reciprocal of time i.e. 1/t
what is the activated complex
the stage reached where an intermediate product is formed
Define Activation energy
The minimum energy needed by colliding particles to form the activated complex
Define catalyst
is a substance which increases the rate of a particular, without being used up in a reaction
what is standard enthalpy of combustion definition
value given for 1 mole of a substance burning completely at standard temp 25°C and pressure 1 atmosphere.
