F322-Rates Of Reaction
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What 5 key factors change the rate of a reaction?
Temperature Pressure Surface area Catalyst Concentration
Describe what happens to the rate of reaction over time
As the reaction proceeds, the reactant particles are used up, and their concentration decreases. Therefore, there are fewer collisions and a smaller number of successful collisions per unit time.
What temperature increases the rate of reaction?
A higher temperature
Does a catalyst increase the rate of a reaction?
Yes
Does the rate of reaction increase with smaller of larger pieces of reactants?
Smaller pieces
Does a high or low concentration increase the rate of reaction?
High concentration
What must particles do to react?
1-collide in the right orientation 2-have enough energy to break bonds
Define Activation energy
The minimum energy required to start a reaction by the breaking of bonds
Define rate of reaction
The change in concentration of a reactant or product per unit of time
What types of reactions are affected by changes in pressure?
Gas Reactions
Use collision theory to explain how increasing the pressure of the reactants affects the rate of reaction
The greater the pressure, the faster the reaction. This is because there are more particles per unit volume, therefore there a greater number of collisions and more successful collisions per unit time
Use collision theory to explain how increasing the temperature affects the rate of a reaction.
An increase in temperature increases the rate of reaction. This is because at higher temperatures there are a greater number of particles with energy that is higher than the activation energy. Therefore, there will be a greater number of successful collisions per unit time
Catalysts are able to speed up reactions by..
Providing an alternative reaction route With a lower activation energy
Explain how the catalyst speeds up the decomposition of Nitrogen(II) Oxide
• reactant molecules are adsorbed onto the surface • reaction occurs on the surface (bonds are weaker) • product molecules are desorbed
Explain why catalysts have a large surface area
It increases the rate of the reaction
Why is it important to remove NO from car exhaust gases?
Because it is toxic & acidic so contributes to acid rain
Name a catalyst used in the chemical industry
Nickel catalyst used in hydrogenation to make margarine
What type of catalyst does the Haber Process use? & what is the use?
Iron catalyst Used to fertilise plants
What is cracking used for?
Making useful short alkenes & alkenes
What effect does a catalyst have on the rare of reaction? How does it achieve this effect?
A catalyst speeds up a reaction by providing an alternative route with a lower activation energy. The reaction is faster as a greater number of particles have an energy that is higher than the activation energy. So there will be a greater number of successful collisions per unit time.
Catalytic converters use what catalyst?
Platinum, palladium or rhodium catalyst (heterogeneous catalyst)
What catalyst does cracking use?
Aluminium Oxide catalyst (heterogeneous)