Rates of Reaction and Energy Changes Flashcards
What is the equation for ROR?
Rate of reaction= Amount of reactant used or product formed/ time
How can you measure the ROR when a precipitate is formed?
Put a black cross below a beaker containing 1 reactant and time how long it takes for cross to disappear after 2nd reactant added.
Define “activation energy”
Minimum amount of energy required for a reaction to occur between two reacting particles.
What must happen for a reaction to occur?
Particles must collide at correct orientation with enough energy to react.
In terms of particles, what 2 things could happen when ROR increases?
More frequent collisions and energy of collision increase.
How can the ROR be increased?
Increasing: Temperature Concentration SA/ V ratio Add a catalyst
How does temp affect ROR?
Increases it because reactants have more activation energy and more successful collisions.
How does SA affect ROR?
Increases it because a bigger SA means more exposed particles so more frequent, successful collisions.
How does a catalyst affect ROR?
Increases it because it provides an alternate reaction pathway with a lower activation energy. More particles have enough energy to overcome activation energy, more successful collisions.
How does concentration affect ROR?
Increases it because there are more reacting particles in the same volume so more frequent collisions.
A graph showing time and amount of gas given off during experiment has a steep gradient? What ROR is it?
Fast
Define catalyst
A substance which speeds up rate of a reaction without being chemically changed at the end.
How does a catalyst speed up ROR?
Provides an alternate reaction pathway with a lower activation energy.
Define an enzyme
Enzymes are biological catalysts that increase RORs in living cells.
Define ENDOTHERMIC
A reaction that takes place in heat energy from surroundings.
