The Rate Of Chemical Change Flashcards
How do you find the speed of reaction from a graph?
Recording amount of product formed
What does the steepness of the line mean?
The steeper the line on the graph, the faster the rate of reaction, the line becomes less steep when the reactants are used up.
What is collision theory?
The more collisions there are the faster the reaction is.
They have to collide with enough energy to break bonds in reactants, called activation energy.
What does rate of reaction depend on?
Temperature
Surface area
Concentration/pressure
Presence of a catalyst
What happens when temperature is increased?
Temp increased
Particles moving faster
Collide more frequently
Have more energy to make the reaction happen
What happens when pressure is increased?
If a solution is made more concentrated
More particles are knocking around in the same volume
When the pressure of a gas is increased
The same number of particles occupies a small place
Collisions are more frequent
What does increasing surface area do?
Break it up into smaller pieces Increased its SA to volume ratio Same volume of the solid Particles have more area Collisions more frequent
What does using a catalyst do?
Speeds up a reaction but isn’t used up
Decrease activation energy by providing an alternative reaction pathway
What are enzymes?
Biological catalysts
What is the mean rate of reaction equation?
Amount of reactant used/product made
____________________________________
Time
Precipitation and colour change?
Record visual change if the intial solution is transparent and product is pecipitate.
You can put an X below the flask and observe how long it takes for the cloudiness to cover it.
Could time how long a liquid takes to loose or gain colour.
Results are subjective though.
Change in mass experiment?
Measuring speed of reaction that produces a gas is done on a mass balance.
The quicker the measure drops the faster the reaction.
Take measurements at regular intervals.
Most accurate but releases gas.
The volume a gas has given off practical?
Involves the use of a gas syringe to measure the volume of gas.
More gas, faster reaction.
Accurate to the nearest cm3.
Regular intervals.
