GCSE CHEMISTRY Flashcards
(31 cards)
Rates of reactions : what is the rate of chemical reactions
The rate of chemical reactions is how fast the reactants are changed into products
What is an example of a slow chemical reaction
One of the slowest reactions is the dusting of iron
What are examples of slow reactions that include chemical weathering
The examples are like acid rain damage to limestone buildings
What is an examples of moderate speed reactions
An example of moderate speed reaction would be metal magnesium reacting with an acid to produce a gentle stream of bubbles
What type of reaction if burning
Burning is a fast reaction
What are explosives
Burning is a fast reaction but explosions are even faster and release a lot of gas.
What is the speed of an explosive
Explosive reactions are all over in a fraction of a second
How do u calculate the speed of a reaction
Amount of reactant/product formed
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Time
What does the steeper line on the graph show
The steeper line on the graph shows how fast that rate of reaction is
How is the quickest reaction shown
The quickest reaction is shown to have the steepest line and become flat in the least time
What happens over time ???
Over time the line becomes less steep as true reactant is used up
What must particles do in order to react
Particles must collide with enough energy in order to react
How are rate of reactions explained
They are explained perfectly by the Collision theory
What time the 3 ways to measure the rate of reactions
1) precipitation and colour change
2) change in mad and colour change
3) the volume of gas of given off
Precipitation and colour change
1) the visual changes are when the solution changes from a transparent to opaque
2) I set the mark through the solution and measure how long it takes to disappear - the faster the mark disappears the quicker the reaction
3) if the reactant is flourless the product is colourless u can’t time how long it takes to lose or agin colour
what is the collision frequency?
the collision frequency of the reacting particles (how often they collide) the more collisions there are the faster the reaction is.
what happens if you double the rate of the reaction?
doubling the frequency of the collisions doubles the rate
what is transferred during the collisions
energy is transferred during a collision. they have to collide with enough energy for the collision to be successful
what is activation of energy?
it is the minimum amount of energy that particles need to react.
why do particles need energy?
they need energy to break bonds in the reactions and start the reaction.
what are the 4 things that rate of reactions depend on?
1) temperature
2) concentration of the solution or the pressure of gas
3) surface are- this changes depending on the size of the lumps of a soild
4) the presence of a catalyst.
what does more collisions do?
more collisions increase the rate of reaction
how can all the four term be explained
all the four methods of increasing the rate of reaction can be explained in terms of increasing the umber of successful collisions between the reactions of particles.
what does increasing the temperature do?
when the temperature in increased, the particles all move faster.
if they move faster, they’re going to collide more frequently. also the faster they move the more energy they have, so more of the collisions will have enough energy to make the reaction happen.
