Rates of reactions Flashcards
What does rate mean?
In a chemical reacition
A meausure of how quickly the reactions are converted in to products
What is the formula for calculating rate of chemical reaction?
Rate = Amount of reactant used or loss/time taken
Volume
Rate = Amount of product formed/time taken
Mass
How does the precipitation method take place?
You mix the two reactant (clear) solution and put the flask on a piece of paper that has a mark on it
Observe the mark through the mixture and meausre hoe long it takes for the mark to br obscured. The faster it disappears, the faster the reaction
The result is subjective different people might not agree when the mark
How can you calculate the rate of reaction by measuring the change in mass?
Use a balance to monitor how the mass changes overtime
Take measurements at regular intervals
The quicker the reading an the balance the faster reaction
Plot your results on a graph
Draw a tangent and calculateits gradient to find the rate at a particular time
(Usually gas given off)
How can you use a gas syringe to measure the rate of a chemical reaction?
USe the gas syringe to monitor howthe volumeof gas changes over time
Take measurements at regular intervals
Plot your results on a graph
Draw a tangent and calculateits gradient to find the rate at particular time
What are the four factors affecting rate?
Surface area, temperature, concentration, pressure
What is activation energy?
The minimum enery needed for a reaction to occur
Whats a catalyst?
A catalyst speeds up a chemical reaction without being used up itself and lower the activation energy of a reaction
How can you make collisions increase?
Increase energy and frequency of collisions
Explain how temperature affects rate
As the temperature increases the rate of reaction also increases because the particles gain more energy and move faster so the are more succesful collisions (reactions only happen if particles collide with enough energy)
Explain how concentration affects rate
As the concentration increases the rate of reaction also increase beacuse there are more particles in the same area / volume so more collisions are likely to take place.
Explain how surface area affects rate
As the surface area increase the rate of reaction also increases beacause if one reactant is a solid, breaking it into smaller pieces would increase its SA to Volume ratio so the particles around it will have more to work on leading to the frequency of collisions to increase
Explain how pressure affects rate
As pressure increases the rate of reaction also increases beacuse increasing pressure means the particles become more crowded (more particles per unit of volume) so collision are more frequent
How do catalyst help the rate of reactions?
Catalyst provide an alternative route which require less activation energy
