The rate and extend of chemical change Flashcards
(20 cards)
What is the defonition of a catalyst
An , unchangeable chemical substance whcih speeds up chemical reaction
How does a catalyst work
Catalysts lower activation energy
What do we call a biological catalyst
Enzyme
What does the term rate of reaction mean
The amount of products reactants used up in a given time
Why does the rate of reaction constantly decrease
as reactants turn into products . the frequency of succesfull collions per seconds decreases
Why do small particles increase the rate of reaction
small particles have a larger surface area, meaning more particles are exposed. This means there is a higher amount of successful collisions per second.
Why does a high temperature increase the rate of reaction
The higher the temperature , the higher the rate of reaction , the particles have more kinetic energy so move faster and \collide more frequently.
Why does a high concentration increase in the rate of reaction
More particles closer together,in a given volume meaning there is a higher amount of successfull collisions per second.
Why does the use of a catalyst increase the rate of reaction
A catalyst reduces the amount of activation energy required .there is an higher amount of particles with enough energy to react, so more successfull collisons per second.
why does a high pressure increase the rate of reaction
A higher pressure results in the particles being compressed into a smaller volume. This increases the amount of successfull collisions per second.
What are the three ways to measure rate of reaction
.Volume of gas using a measuring cyclinder or gas syringe
.Change in mass
. formation of a precipitate (dissapearing cross)
Define equillibrium
Occurs in a closed system when the rate of the forward and backwards reaction are the same.
Five factors affecting the rate of reaction
.Concentration of reactants
.pressure of gases
.surface area
.temperature
.catalysts
What is the collision theory
Chemical reactants can only occur when reacting particles collide with eachother, with sufficient energy
What is a reversible reaction
A reversible reaction occurs when the products of a reaction can react backwords to produce. the orignal reactants
La chateliers principles
If a system is at equilibrium and a change is made to any of those conditions , then the system responds to counteract change and restore the equillibrium.
Name 3 common ways of measuring rate of reaction
.loss in mass of reactants
.volume of gas produced
.time for a solution to become opaque
describe measuring the rate by monotoring mass loss
.place the reaction flask on a balance
.in the reactions a gas is given off , so record the decrease in mass
.plot a graph of time vs mass
describe measuring the rate by monotoring the volume of a gas
.connect a gas syringe to a reaction flask
.measure the volume of the gas
.plot a graph of volume vs time
describe measuring the rate by monotoring the disapearance of a cross
. take a piece of paper and mark x on it
.put the reaction flask on this cross
.mix the reagents , and measure how long it takes for a cloudy mixture to conceal a cross
