Rates of Reaction Unit 2 Topic 4 Flashcards
What is the rate of reaction?
Measure of hot fast/slow the reaction is
How do we measure the rate of reaction?
Measure how quickly products form in a given time OR how quickly reactants are used up in a given time
What is the equation for rate of reaction?
What are the units for rate?
Rate = 1/time
s-1
Fill in the blanks:
The steeper the slope, the ______ the reaction
The steeper the slope, the faster the reaction
What can change the speed of the reaction?
Surface Area
Concentration
Temperature
Catalysts
Why are rates of reaction important in the chemical industry?
Commercial products: Ammonia for fertilisers, H2SO4 for detergents + polythene for packaging)
Want reactions to be as fast as possible + good product yield
What does collision theory state?
For a reaction to take place, reacting particles must collide with sufficient activation energy.
What is activation energy?
Minimum energy required for a reaction to take place between reacting particles
As surface area is ________, ____particles are exposed, so there are more frequent collisions.
In a fixed period of time there are ____ collisions with the minimum energy required to react therefore the rate of reaction _______
As surface area is Increased, more particles are exposed so there are more frequent collisions.
In a fixed period of time there are more collisions with the minimum energy required to react therefore the rate of reaction increases.
In the reaction between marble chips and hydrochloric acid which particles react?
When there are successful collisions, what is formed?
Hydrogen ions from HCL + carbonate ions from marble chips.
Bubbles of CO2
What happens to the reaction rate as time progresses?
As time progresses each reaction slows down. This is because reactants are being used up + as time progresses there are fewer reactants available so a slower reaction.
Write the word equation for the reaction between marble chips and hydrochloric acid.
CaCO3 (s) + 2HCl (aq) -> CaCl2 (aq) + CO2 (g) + H20 (l)
As the concentration of one reactant is increased, there are more particles in the ____ volume so there will be ____ collisions.
In a fixed period of time there are ____ collisions with the _______ energy required to react therefore rate of reaction ________.
As the concentration of one reactant is increased, there are more particles in the same volume so there will be more collisions.
In a fixed period of time there are more collisions with the minimum energy required to react therefore rate of reaction increases.
As the temperature of the reaction is ________, the particles have more energy. The particles are likely to have energy equal or greater than the activation ______. Therefore there will be ____ successful collisions and the reaction rate will _______.
As the temperature of the reaction is increased, the particles have more energy. The particles are likely to have energy equal or greater than the activation energy. Therefore there will be more successful collisions and the reaction rate will increase.
What is a catalyst?
A substance that increases the rate of reaction without being used up.
For a reaction to take place, particles must _______and they must have sufficient ______ to overcome the activation energy barrier of the reaction
Catalysts _______ the reaction rate by _____ the activation energy of a reaction. This means that in a catalytic reaction when particles collide ____ of them have sufficient energy to overcome the energy barrier to form products and the reaction is faster.
For a reaction to take place, particles must collide and they must have sufficient energy to overcome the activation energy barrier of the reaction. Catalysts increase the reaction rate by lowering the activation energy of a reaction. This means that in a catalytic reaction when particles collide, more of them have sufficient energy to overcome the energy barrier to form products and the reaction is faster.
Give an example of a catalyst and an element?
Iron with Manganese Oxide
Explain how a catalyst works using the term activation energy.
Offers alternate route with lower Activation Energy.
Give 2 examples of where catalysts are used in the chemical industry?
Iridium compound - Making Ethanoic Acid (Vinegar)
Vanadium Oxide - Making Sulfuric Acid (Contact Process)
Why do chemists want to use catalysts and develop use of catalysts?
New ways of making materials which may use less energy or find new lower energy routes to get larger product yields. Also may lower waste products (less chemical pollution)
What is a datalogger used for in reaction between sodium thiosulfate + hydrochloric acid?
Connected to computer, plot graph of amount of light passing through against time.
What happens if you increase the surface area of reactants?
More particles exposed to other reactant. More frequent collisions with sufficient activation energy, reaction rate increases.
How do you collect the gas given off in a reaction?
Gas syringe
Does the volume of product increase in these reactions?
No, just the rate.
What happens when sodium thiosulfate reacts with an acid? (Colour change)
Yellow suspension of sulfur formed
Solution becomes cloudy
What happens when potassium iodate, starch arsenious acid + potassium iodide are added?
Form black iodine.
Label the activation energy diagram?
Label from book
In the reaction between marble chips + hydrochloric acid, which particles react?
Hydrogen ions (H^+) from HCl + carbonate ions (Co3^2-) from marble chips (CaCO3)
What happens if there is a low concentration in a reaction?
Smaller number of collisions in a given time. Only some collisions will have energy greater than or equal to activation energy so reaction rate is slow.
If the concentration of a reactant is increased, does the total volume of product increase?
No, it stays the same.
Would an increase in concentration or temperature speed up the reaction most?
Temperature as it increases energy rather than just number of particles available of 1 reactant.
What do catalytic converters do?
Reduce air pollution as they allow pollutant gases like carbon monoxide and nitrogen oxides to be converted into less harmful gases.
