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20 Cards in this Set
- Front
- Back
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What is the rate of a chemical reaction? |
Measures how fast a reactant is being used up or how fast a product is being formed |
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What is the equation to calculate the rate? |
Change in Concentration / time |
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What is the unit for rate |
Moldm^-3 s^-1 |
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What factors affect the rate of a chemical reaction |
Conc Temp Use of a catalyst Surface area of reactants |
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What is the collision theory? |
States that 2 reacting particles must collide for a reaction to occur |
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What 2 conditions need to be met for a collision to be effective |
The particles collide with the correct orientation The particles have significant energy to overcome the activation energy barrier of the reaction |
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How does concentration affect ROR |
Increased conc increases ROR
As conc increases the number of particles in the same vol Particles are closer together and collide more frequently. In a given period there will therefore be more effective collisions |
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How does pressure affect ROR |
As pressure increases ROR increases When a gas is compressed into a smaller volume the pressure of a gas is increased and ROR increases The conc of gas molecules increases as the number of gas molecules occupy a smaller vol The gas molecules are closer together and collide more frequently, leading to more effective collisions in the same time |
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What are 2 methods that can be used to investigate the ROR that produces a gas |
Monitoring the volume of gase produced at regular time intervals using gas collection Monitoring the loss of mass of reactants using a balance |
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How do we monitor the production of a gas using gas collection |
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How do we monitor the loss of mass of reatants using a balance? |
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What is a catalyst |
A substance that changes the rate of a chemical reaction without undergoing any permanent change itself |
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What are the properties of a catalyst |
Its not used up in the chemical reaction The catalyst may react with a reactant to form an intermediate or may provide a surface on which the reaction can take place A catalyst increases the ROR by providing an alternative reaction pathway of lower activation energy |
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What the different types of catalysts? |
Homogeneous catalyst Heterogeneous catalyst |
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What is a Homogeneous catalyst? |
Has the same physical state as the reactants Catalyst reacts with the reactants to form an intermediate Intermediate then breaks down to give the product and regenerates the catalyst |
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What is a Heterogeneous catalyst? |
Has a different physical state from the reactants Usually solids in contact with gaseous reactants or reactants in solution |
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What are the sustainability and economic pros when using a catalyst |
Catalyst increases ROR by lowering AE. This reduces the temp needed for the process and the energy requirements less energy means less electricity or fossil fuel used, making the product faster and using less energy can cut costs and increase profitability Modern fouc on processes with high atom economies and few pollutants, using less fossilfuels will cut CO2 emissions |
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What is the boltzmann distribution |
The spread of molecular energies in gases is known as the boltzmann distribution |
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What is the effect of temperature on the Boltzmann distribution? |
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What is the effect of a catalyst on the Boltzmann distribution? |
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