Rate of Reaction Flashcards
What is the rate of a chemical reaction?
How fast the reactants are changed into products.
Give an example of slow, moderate and fast reactions.
Slow = rusting of iron
Moderate = Metal reacting with acid to produce hydrogen
Fast - explosion
What are the four factors that affect rate of reaction?
Temperature
Concentration
Surface area
Catalysts
How does temperature affect rate of reaction?
Higher temperature = faster rate. Particles gain more energy when heated so collide more often and with more energy.
How does concentration affect rate of reaction?
Higher concentration of reactants = faster reaction. Concentrated solution means more particles in the same volume, making collisions more likely. Also with gas increasing pressure.
How does surface area affect rate of reaction?
Larger surface area = faster rate of reaction. If reactant is a solid, breaking into smaller particles will increase surface area. Meaning more particles will react immediately with more space, increasing frequency of collisions.
How does a catalyst affect the rate of reaction?
A catalyst speeds up reactions
What are the two parts of the collision theory?
1) The collision frequency - higher collision frequency, faster reaction.
2) The energy transfer of a collision - particles need to have enough energy to collide
Explain collision theory
Changing collision frequency or energy transfer of a reaction will change the rate of reaction.
How to increase rate of reaction?
Increase the frequency of collision so probability of colliding reactants is higher and increase particle energy so more collision happen.
What is activation energy?
Minimum amount of energy that particles must have in order to react.
What is a catalyst?
Substance that can speed up a reaction without being changed or used up in a reaction (so they don’t appear in the chemical equation)
How do catalysts work?
They decrease activation energy by providing an alternative reaction pathway with lower activation energy.
Caluculate rate of reaction?
How is the rate of reaction shown on a graph?
By the gradient (steepness) of the line. Steeper line = faster rate of reaction
Do reactions start quickly or slowly and why?
Reactions start quickly because there are lost of reactant particles so at the beginning the collision are very frequent. As it progresses, reactant gets used up so their are fewer collisions.
How do you find rate of reaction at a particular point?
By drawing a tangent (straight line) that touches the curve at a particular point without crossing it.
Methods of testing
-Time taken for mark to disappear with precipitate
-measure mass decrease of a reaction over time
-measure gas volume released
