Reactions - Rate and Extent of Chemical Change Flashcards
what is the rate of reactions?
how fast the reactions are changed into products.
What theory can revision rate be explained by?
collision theory.
What does the collision theory say?
a reaction will only take place when particles collide.
The particles will also have to have a certain amount of energy when they collide otherwise they won’t react.
What is the minimum amount of energy called needed for a reaction?
Activation energy.
How can collision theory explain rate of reactions?
More often particles collide the faster reaction will happen.
What four things does the rate of reaction depend on?
Temperature
Concentration of a solution
Surface area of a solid
Whether a catalyst is used.
How does increase in temperature increase the rate?
When temperature increases, particles move quicker.
If they move faster, they collide more frequently.
They can also have more energy’s
How can increasing concentration or pressure increase the rate?
If a solution is more concentrated, it has more particles in the same volumes
And when the pressure of a gas is increased, it means the same number of particles are now in a smaller space:
So collision en between the particles are more frequent.
How does increasing the surface area increase the rate of reaction)
If one or the reactants is a solid, then breaking it up into smaller pieces will increase its surface area to volume ratio.
So this means the same amount of solid has a bigger surface area.
So more of the solids particles are available to particles of the other reactant, and collision will be more frequent.
How does using a catalyst increase the rate of reactiknV
It speeds up reaction, lowers activation energy.
Enzymes are biological catalysts and catalyst reactions in living things.
Explain steps of the Marble Chips and Hydrochloric Acid reaction to produce CO2.
1- measure out a set volume of dilute hydrochloric acid using a measuring cylinder.
2- carefully pour into conical flask.
3- measure out a set mass of marble chips.
4- add the marble chips to the flask and quickly attach a delivery tube and a gas syringe to the flask, so this before gas escapes.
5- start the stopwatch straight away.
6- gas will collect in gas syringe? take readings of volume of gas at regular intervals.
7- repeat experiments using different concentrations of acid to test the effect of concentration on rate of reaction.
What is the symbol for a reversible reaction?
A + B -> C + D
<-
Half of an arrow on top, half on bottom.
What does it mean by reversible reactions will reach equilibrium?
- As the reactants react their concentrations fall. the forward reaction slows down.
- As more and more pedicure are made the backward reaction will speed up.
- After a while the forward reaction and backward reaction will be going at the exact same rate, This system is at equilibrium:
Equilibrium doesn’t mean there are the same amounts of products and reactants, it just means that the amount of products and reactants aren’t changing anymore. - Equilibrium is only reached if the reaction takes place in a closed system.
What does a closed system mean in a reversible reaction)
Means that none of the reactants or products can escape and nothing else can get in.
How can reversible reactions be endothermic and exothermic?
If it is endothermic (takes in heat) in one direction it will be exothermic in the other.
