Rate of reaction Flashcards
(39 cards)
What does the rate of a chemical reaction describe?
How quickly the products are formed
How do you tell if a chemical reaction has happened?
Effervescence, energy changes colour change, precipitation
When might colour change occur?
2 substances react or thermal decomposition
What is thermal decomposition?
When a compound is broken down by heating up
What do some chemical reactions result in?
A product that’s in a different state of the reactants
What is a chemical reaction?
A process during which a new substance is formed
What must you do for something to be classified as a chemical reaction?
You must make something new.
Simply changing state, eg. when water freezes into ice, it doesn’t make a new substance (it’s still water and is only a physical change)
Why is it useful to know the rate of a reaction?
To plan chemical & manufacturing processes better
To design medicines so that they will be taken up by the body at a safe rate
To know when your meal/cake is ready
When do chemical reactions occur?
At different rates
What are explosions results of?
Extremely fast reactions
What is rusting a result of?
A very slow reaction
What factors affect the rate of a chemical reaction?
Temperature
Particle size
Concentration
Catalysts
What is a catalyst?
A substance which speeds up (catalyses) a reaction without getting used up
What are reactions that give off gases easy to do?
Follow
How can we measure a gases volume or mass?
As the reaction takes place, the gas leaves the reaction vessel, and we can measure its volume or mass
What can we use to measure the volume or mass of gas?
An inverted measuring cylinder filled with water (can’t be used if the gas is water soluble)
A gas syringe
A balance (to measure mass loss)
When is the end point of a reaction reached?
Reached when the reaction is complete
How can the end point happen?
When one of the reactants is completely used up
What happens to the graph once the end point of a reaction is reached?
The graph is completely flat
This is because no more products are being made
How can we measure data collected over the course of a reaction?
Graphs
What does the shape of a graph tell us?
How quickly a reaction happens and when the end point is reached
What does the slope of the graph correspond with?
Reaction rate
What do steeper slopes mean?
The steeper the slope, the higher the rate
It’s faster
What does the height of the graph correspond with?
The quantity of products made
