# Rates of reactions

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• Created by: Megan1404
• Created on: 27-02-16 16:05
What does the term "rate of reaction" mean?
It is the amount of reactant used up or the amount of product made within a given time.
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What is needed for a chemical reaction to happen?
Reactant particles must collide with enough energy called activation energy to change into products.
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What is activation energy?
It is the minimum amount of energy needed to start a reaction.
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What are five ways in which we can increase the R.O.R?
Increase the temperature; increase the concentration of reactants; increase the S.A of reactants; increase the pressure of gases; add a catalyst.
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What are the different ways we can monitor the R.O.R?
Measure the rate at which the mass of reactants decreases; measure the volume of gas given off; measure the decreasing light passing through a solution.
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What is collision theory?
Reactions can only take place when reactant particles collide with enough energy called activation energy to change into products.
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Why does increasing the concentration of reactants in solutions increase the R.O.R?
The rate increases because there are more reactant particles per unit volume. This means that there is a higher chance of reacting particles colliding and changing into products.
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Why does increasing the S.A of solid reactants increase the R.O.R?
Increasing the S.A provides more reactant particles to be available for collisions. This means that there is a higher chance of reactant particles colliding and changing into products.
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Why does an increase in temperature increase the R.O.R?
When temperature is increased reactant particles have more energy and they move faster. As a result the particles collide more often and with more activation energy so the R.O.R increases.
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Why does increasing the pressure of reacting gases increase the R.O.R?
The rate increases because the particles are closer together so there is a higher chance of reacting particles colliding and changing into products.
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What is a catalyst?
A catalyst speeds up the rate of reaction without itself being used up.
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How does a catalyst speed up the R.O.R?
Catalysts lower the activation energy of a reaction.
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Why are catalysts generally used in the form of powders, pellets or fine gauzes?
This increases the S.A of the catalysts and so more reactants can be converted into products and the reaction is faster.
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## Other cards in this set

### Card 2

#### Front

What is needed for a chemical reaction to happen?

#### Back

Reactant particles must collide with enough energy called activation energy to change into products.

### Card 3

#### Front

What is activation energy?

### Card 4

#### Front

What are five ways in which we can increase the R.O.R?

### Card 5

#### Front

What are the different ways we can monitor the R.O.R?