Reaction Rates Flashcards
(19 cards)
What is a reaction rate?
A measure of how quick a reaction happens
What is formula for rate of reaction?
Rate of reaction =
amount of reactant used or amount of product formed
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Time
What does rate of reaction depend on?
Temperature
Concentration
Pressure for gases
Size of particles in solids
What is collision theory?
How often reacting particles collide
The more there are the faster reaction
What happens to particles when temperature increases?
Particles move faster
More collisions
What happens to particles in a concentrated solution?
More particles of reactant
Collisions more likely
Reaction rate increases
What happens if there is increased pressure in a gas?
Particles more crowded
Frequency of collisions increase
Rate of reaction increases
Is the rate of reaction faster for solids with a larger surface area or smaller?
Larger
Explain why breaking a solid reactant into smaller pieces increases rate of reaction
Increases surface area to volume ratio
More solid exposed
Particles around have more area to work on
Frequency of collisions increases
What is a catalyst?
A substance which increases rate of reaction
How does a catalyst work?
Decreases activation energy needed for a reaction to occur
Provide an alternative reaction pathway that has a lower activation energy
More of particles have at least minimum amount of energy needed for a reaction to occur
What are enzymes?
Biological catalysts
What do enzymes do?
Speed up chemical reactions in living cells
What chemical reactions are catalysed by enzymes?
Respiration
Photosynthesis
What are enzymes from yeast cells used for?
Fermentation
Alcoholic drinks
What is activation energy?
Minimum amount of energy needed for bonds to break
Having to climb up hill before ski down other side
What is a positive energy change?
Endothermic
Bonds break
Energy supplied to break bonds
What is a negative energy charge?
Exothermic
Energy released when new bonds are formed
What type of process is bond forming?
Exothermic
