C8.5 - The effect of catalysts Flashcards
Sometimes when might a reaction only work?
Sometimes a reaction might only work if you use very high:
1. Temperatures
Or,
2. Pressures
Sometimes a reaction might only work if you use very high temperatures or pressures.
What can this cost industry?
This can cost industry a lot of money
Sometimes a reaction might only work if you use very high temperatures or pressures.
This can cost industry a lot of money.
However, how can you speed up some reactions and reduce energy costs?
You can:
1. Speed up some reactions
2. Reduce energy costs
by using catalysts
Catalyst
A catalyst is a substance that speeds up a chemical reaction by providing a different pathway for the reaction that has a lower activation energy
Why can a catalyst be used over and over again?
A catalyst can be used over and over again, because it is not used up in the reaction
What is needed for different reactions?
Different catalysts are needed for different reactions
Different catalysts are needed for different reactions.
What do many of the catalysts used in industry involve?
Many of the catalysts used in industry involve transition metals
Different catalysts are needed for different reactions.
Many of the catalysts used in industry involve transition metals.
Examples of transition metals that are used in industry as catalysts
Examples of transition metals that are used in industry as catalysts are:
- Iron
- Platinum
Iron is used to make what?
Iron is used to make ammonia
Platinum is used to make what?
Platinum is used to make nitric acid
What form are catalysts normally used in?
Catalysts are normally used in the form of: 1. Powders 2. Pellets Or, 3. Fine gauzes
Catalysts are normally used in the form of powders, pellets, or fine gauzes.
What does this give them?
This gives them the biggest possible surface area to volume ratio
Where are catalysts?
Catalysts are:
- All around you
- In the natural world
- In industry
Catalysts are all around you, in the natural world and in industry.
What are the biological catalysts in living things called?
The biological catalysts in living things are called enzymes
Catalysts are all around you, in the natural world and in industry.
The biological catalysts in living things are called enzymes.
What are these enzymes?
These enzymes are large protein molecules that are folded into intricate shapes to accommodate the reactant molecules called substrates
Catalysts are all around you, in the natural world and in industry.
The biological catalysts in living things are called enzymes.
These enzymes are large protein molecules that are folded into intricate shapes to accommodate the reactant molecules called substrates.
Enzymes are incredibly efficient what?
Enzymes are incredibly efficient catalysts
The transition metals platinum and palladium are used in what?
The transition metals:
1. Platinum
2. Palladium
are used in the catalytic converters in cars
The transition metals platinum and palladium are used in the catalytic converters in cars.
How is their surface area to volume ratio maximised?
Their surface area to volume (SA :V) ratio is maximised, as they are coated onto a honeycombed support
What do catalysts not do?
Catalysts do not:
1. Increase the frequency of collisions between reactant particles
Nor do they
2. Make collisions any more energetic
Catalysts do not increase the frequency of collisions between reactant particles, nor do they make collisions any more energetic.
How do they increase rates of reaction?
Catalysts increase rates of reaction by providing an alternative reaction pathway to the products, with a lower activation energy than the reaction without the catalyst present
Catalysts increase rates of reaction by providing an alternative reaction pathway to the products, with a lower activation energy than the reaction without the catalyst present.
So with a catalyst, a higher proportion of the reactant particles have what?
With a catalyst, a higher proportion of the reactant particles have sufficient energy to react
With a catalyst, a higher proportion of the reactant particles have sufficient energy to react.
What does this mean?
This means that the:
- Frequency of effective collisions, collisions that result in a reaction, increases
- Rate of reaction speeds up
Catalysts are often what?
Catalysts are often very expensive precious metals
Catalysts are often very expensive precious metals.
What are gold, platinum and palladium?
- Gold
- Platinum
- Palladium
are all costly
Catalysts are often very expensive precious metals.
Gold, platinum and palladium are all costly, but are the most effective catalysts for particular reactions.
What is it usually cheaper to do?
It is usually cheaper to use a catalyst than to pay for the extra energy needed without one
It is usually cheaper to use a catalyst than to pay for the extra energy needed without one, because to get the same rate of reaction without a catalyst would require higher temperatures and/or pressures.
So what do catalysts do?
So catalysts:
- Save money
- Help the environment
It is usually cheaper to use a catalyst than to pay for the extra energy needed without one, because to get the same rate of reaction without a catalyst would require higher temperatures and/or pressures.
So catalysts save money and help the environment, because using high temperatures and pressures often involve burning fossil fuels.
So what does operating at lower temperatures and pressures do?
Operating at lower temperatures and pressures:
- Conserves these non-renewable resources
- Stops more carbon dioxide entering the atmosphere when they are burnt
Climate change
Climate change is the change in global weather patterns that could be caused by excess levels of greenhouse gases in the atmosphere
Not only does a catalyst speed up a reaction, but what does it also do?
Not only does a catalyst speed up a reaction, but it also does not get used up in the reaction
Not only does a catalyst speed up a reaction, but it also does not get used up in the reaction, so a tiny amount of catalyst can be used to speed up a reaction over and over again.
However, what do the catalysts used in chemical plants eventually become?
The catalysts used in chemical plants eventually become ‘poisoned’
The catalysts used in chemical plants eventually become ‘poisoned,’ so that they do not work anymore.
Why does this happen?
The catalysts used in chemical plants eventually become ‘poisoned,’ so that they do not work anymore, because impurities in the reaction mixture:
- Combine with the catalyst
- Stop it working properly
Why do catalysts not appear in the balanced equation for a reaction, but can be written above the reaction arrow?
Catalysts do not appear in the balanced equation for a reaction, but can be written above the reaction arrow, because:
- Catalysts change only the rate of reactions
- The products do not change
A catalyst is a substance that speeds up a chemical reaction by providing a different pathway for the reaction that has a lower activation energy.
The catalyst is what at the end of the reaction?
The catalyst is chemically unchanged at the end of the reaction
Catalysts are normally used in the form of powders, pellets, or fine gauzes.
This gives them the biggest possible surface area to volume ratio, making them what?
This gives them the biggest possible surface area to volume ratio, making them as effective as possible
Catalysts are normally used in the form of powders, pellets, or fine gauzes.
This gives them the biggest possible surface area to volume ratio, making them as effective as possible, because the reactions they catalyse often involve what?
This gives them the biggest possible surface area to volume ratio, making them as effective as possible, because the reactions they catalyse often involve gases reacting on their surfaces
Catalysts are all around you, in the natural world and in industry.
The biological catalysts in living things are called enzymes.
These enzymes are large protein molecules that are folded into intricate shapes to accommodate the reactant molecules called substrates.
Enzymes are incredibly efficient catalysts and work at what temperatures?
Enzymes:
- Are incredibly efficient catalysts
- Work at relatively low temperatures
Catalysts are all around you, in the natural world and in industry.
The biological catalysts in living things are called enzymes.
These enzymes are large protein molecules that are folded into intricate shapes to accommodate the reactant molecules called substrates.
Enzymes are incredibly efficient catalysts and work at relatively low temperatures, doing what?
Enzymes:
1. Are incredibly efficient catalysts
2. Work at relatively low temperatures
,conserving energy in the biotechnology industry
Catalysts are often very expensive precious metals.
Gold, platinum and palladium are all costly, but are what?
- Gold
- Platinum
- Palladium
are all costly, but are the most effective catalysts for particular reactions
Catalysts are often very expensive precious metals.
Gold, platinum and palladium are all costly, but are the most effective catalysts for particular reactions.
It is usually cheaper to use a catalyst than to pay for the extra energy needed without one, because what?
It is usually cheaper to use a catalyst than to pay for the extra energy needed without one, because to get the same rate of reaction without a catalyst would require higher:
1. Temperatures
and/Or,
2. Pressures
It is usually cheaper to use a catalyst than to pay for the extra energy needed without one, because to get the same rate of reaction without a catalyst would require higher temperatures and/or pressures.
So catalysts save money and help the environment, because what?
So catalysts save money and help the environment, because using high:
1. Temperatures
2. Pressures
often involve burning fossil fuels
It is usually cheaper to use a catalyst than to pay for the extra energy needed without one, because to get the same rate of reaction without a catalyst would require higher temperatures and/or pressures.
So catalysts save money and help the environment, because using high temperatures and pressures often involve burning fossil fuels.
Operating at lower temperatures and pressures conserves these non-renewable resources and stops more carbon dioxide entering the atmosphere when they are burnt, helping to do what?
Operating at lower temperatures and pressures:
- Conserves these non-renewable resources
- Stops more carbon dioxide entering the atmosphere when they are burnt, helping to combat climate change
Not only does a catalyst speed up a reaction, but it also does not get used up in the reaction, so what?
Not only does a catalyst speed up a reaction, but it also does not get used up in the reaction, so a tiny amount of catalyst can be used to speed up a reaction:
1. Over
2. Over
again
Not only does a catalyst speed up a reaction, but it also does not get used up in the reaction, so a tiny amount of catalyst can be used to speed up a reaction over and over again.
However, the catalysts used in chemical plants eventually become ‘poisoned,’ so that they what?
The catalysts used in chemical plants eventually become ‘poisoned,’ so that they do not work anymore
