SC18 Rates of Reaction Flashcards
Formula for Rate of Reaction
amount of reaction used or amount of product formed / time
Define a precipitation reaction
Mix two reactants together and put flask on marked piece of paper, observing the mark through the mixture, measuring how long it takes for the mark to be obscured
Define a Change in Mass reaction
Using a mass balance, gas produced and released can be measured on a balance as the scales go down. The reaction is over when the mass stays the same.
Define a Volume of Gas reaction
Using a gas syringe to collect the gas released. The more gas released in a time period, the faster the reaction.
List the factors that affect Rate
SA, Concentration, Temperature
How does SA affect rate?
Having a larger SA means there is a larger area to work on, so the frequency of collisions will increase.
How does conc. affect rate?
Having a high concentration means there are more particles in the same volume. This makes collisions more likely as there are more particles there to react with
How does temp. affect rate?
An increase in temperature making particles move faster. The faster they move, the more collisions will occur. High temp. also increases the energy of the collisions, so they are more likely to react
Advantages of catalysts
- Speed up reaction
- Only need a tiny bit
- Don’t affect products
Define activation energy
the minimum amount of energy needed for bonds to break and a reaction to start
How do catalysts work?
By decreasing the activation energy needed for a reaction to occur by providing an alternative reaction pathway that has a lower activation energy.
Define enzymes
biological catalysts speeding up reactions in living cells
Examples of reactions catalysed with enzymes
Respiration, photosynthesis, protein synthesis
