A catalyst is a substance that increases the rate of a chemical change reaction without being used up in the process.
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What are catalysts not included in?
The chemical equation for the reaction.
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What does a catalyst do?
Reduces the amount of energy needed for a successful colission. Makes more collisions successful. Speeds up the reaction. Provides a surface for the molecles to attach to, which increases their chances of bumping into each other.
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What acts as a catalyst in biological systems?
Enzymes.
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What are 2 examples of different reactions that need different catalysts?
The cracking of hydrocarbons uses broken pottery. The manufacture of ammonia uses iron.
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How may increasing the rates of chemical reactions be beneficical in industries?
It helps to reduce costs.
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What is a reversible reaction?
A chemical reactions that are reversible, the products can react to produce the original reactants.
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How are these reactions represented?
A(g) + B(g) reversible reaction symbol C(g) + D(g).
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What is an example of this?
Solid ammonium chloride decomposes when heated to produce ammonia and hydrogen chloride gas (both colourless). Ammonia reacts with hydrogen hloride gas to produce clouds of white ammonium chloride.
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How may the direction of reversible reactions be changed?
By changing the conditions.
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What happens if a reversible is exothermic in one direction?
It is endothermic in the opposite direction.
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What is important about the amount of energy given out and taken out by the endothermic and exothermic reactions?
It stays the same.
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What is there none of in a closed system?
There are no reactants that are added and no products are removed.
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What is achieved when a reversible reaction occurs in a closed system?
An equilibrium is achieved when the rate of the forward reaction is equal to the rate of the backward reaction.
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What do the relative amounts of all the reacting substances at equilibrium depend on?
The conditions of the reaction.
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HT What does Le Chatelier's principle states?
It states that if a system in equilibrium is subjected to a change in conditions, then the system shifts to resist the change.
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HT In relation to this, what would happen in an exothermic reaction?
If the temperature is decreased, the yield increases. If the temperature is lowered, the yield increases.
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HT What would happen in an endothermic reaction?
If the temperature is increases, the yield increases. If the temperature is lowered, the yield decreases.
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HT What would happen in reactions involving gases?
An increase in pressure favours the reaction that produces the least number of gas molecules. A decrease in pressure favours the reaction that produces the greater number of gas molecules.
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HT What would happen if the concentration of a reactant or product is changed?
The system is no longer in equlibrium. The system adjusts until it can reach equilibrium once more.
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HT WHat will happen if the concentration of one of the reactants is increased?
The position of equilibrium shifts so that more products are formed until equilibrium is reachd again.
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HT What would happen if the concentration of one of the reactants is decreased?
The position of equilibrium shifts so that more reactants are formed until equilibrium is reached again.
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HT What do these factors together with reaction rates determine?
They determine what the optimum conditions in industrial processes are.
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Other cards in this set
Card 2
Front
What are catalysts not included in?
Back
The chemical equation for the reaction.
Card 3
Front
What does a catalyst do?
Back
Card 4
Front
What acts as a catalyst in biological systems?
Back
Card 5
Front
What are 2 examples of different reactions that need different catalysts?
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