Rates of Reactions Flashcards
Give an example of a slow rate of reaction:
oxidisation (rusting)
Give an example of a medium rate of reaction:
Baking (cakes, cookies etc.)
Give an example of a very fast rate of reaction:
Explosions (e.g. fireworks)
What are the two ways we can measure rates of reaction?
1) Measure the rate at which the reactant is used up.
2) Measure the rate at which a product is formed (i.e. volume of gas made/time taken)
In this equation, which parts are the reactants and which part is the product?
HCl (aq) + Mg (s)»_space;> Mgcl2 (aq) + H2 (g)
HCI (aq) + Mg (s) = REACTANTS
MCl2 (aq) + H2 (g) = PRODUCTS
What is the equation for rate of reactant?
Volume formed / Time in seconds
How do you calculate the MEAN rate of reaction
Quantity of product formed / Time in seconds
convert these into measurements of time:
1 cm3/s
2 cm3/s
4 cm3/s
1 minute
30 seconds
15 seconds
What can the rate of reaction tell us?
How fast reactants turn into products.
There are lots of reactions taking place in the human body and it is important for them to work at the correct rates. Why?
They happen at the correct rate to supply our cells with what they need, whenever required.
How can you measure the rate of reaction using decreasing mass of a reaction mixture?
You can measure the rate at which the mass of a reaction mixture changes if the reaction gives of a gas. You can measure and record the mass at regular time intervals.
How can you measure the rate of reaction using the increasing volume of gas given off?
If a reaction produces a gas, you can use the gas to find out the rate of reaction. You do this by collecting the gas and measuring the volume given off at time intervals.
How can you measure the rate of reaction using the decreasing light passing through a solution?
Some reactions in solutions make a suspension of an insoluble solid (precipitate). This makes the solution go cloudy. You can use this to measure the rate at which the precipitate appears.
What must happen for a chemical reaction to occur?
The reactant particles must collide
What does the rate of reaction depend on?
The rate of successful collisions between reactant particles. (the more successful collisions there are, the faster the rate of reaction)
Things that affect the rate of reaction
- Temperature
- Concentration of reactants in solution
- Pressure of gaseous reactants
- Surface area
- Adding a catalyst
How does temperature affect rate of reaction?
The higher the temperature, the more energy the particles have meaning they can move around more thus allowing them to collide more often which leads to a faster reaction.
How does concentration affect rate of reaction?
The more concentrated the solution (the more particles there are), the greater the chance of collisions with other reactants leading to a faster reaction.
How does surface area affect rate of reaction?
Any reaction involving a solid can only take place at the surface of a solid. If the solid is split into several pieces, the surface area increases which leads to more successful collisions
How does a catalyst affect the rate of reaction
A catalyst substance speeds up a reaction but is chemically unchanged at the end of the reaction. They only change the rate of reaction and not the product.
How do you work out the:
- Area of a square/rectangle?
- Area of a cube?
- Volume of a cube?
1) Width * height
2) Length * width * 6
3) length * width * depth
Calculate the surface area of A cube with the side length of 4cm:
96cm2
Calculate the volume of a cube with a side
length of 4 cm:
64cm3
What does Aq mean?
Aqueous (In solution)
What is pressure?
The number of gas particles given in a certain area.
How can we change pressure?
We can change pressure by changing the amount of particles in a gas as well as the size of a given area.
Why are catalysts beneficial?
- Catalysts reduce activation energy which makes them cheaper.
- Catalysts remain unchanged at the end of a chemical reaction
- Good for making ethanol and it produces Carbon Dioxide not monoxide which is better
What is dynamic equilibrium?
It occurs In a reversible reaction when the forward and backward reactions are going at the same rate.
What is homogenous?
All the reactants are in the same group- same state of matter.
What is Le Chatelier’s principle?
If dynamic equilibrium is disturbed by changing the conditions or oppose the change
