C6 Flashcards
what is the rate of a chemical reaction and example?(2)
what is an example of a moderate speed reaction?
what is burning an example of?
what is even faster than burning?
-How fast the reactants are changed into products
Examples:
-Rustling of iron
-Chemical weathering-acid rain damage to limestone buildings
Example of a moderate speed reaction:
-The metal magnesium reacting with an acid to produce a gentle stream of bubbles
Burning is an example of a fast reaction.But explosions are even faster as they release lot’s of gas they are spread quickly
How can you find the speed of a reaction?
The steeper the line on the graph……?
Overtime the line becomes…….?
The quickest reactions have the………….?
-By recording the amount of product formed or the amount of reactant used up
-The steeper the line the faster the rate of reaction
-Overtime the line becomes less steep as the reactants are used up
-The quickest reactions have the steepest line and become flat in the least time
what does graph 1 represent?
what does graph 2 and 3 represent?
what does graph 4 represent?
-Graph 1 represents the original reaction
-Graph 2 and 3 shows the reaction taking place quicker,but with the same initial amounts of reactants.They also all produce the same amount of product but at different times
-Graph 4 shows more product and a faster reaction.This can only happen if more reactants are added at the start
what is the rates of reaction explained perfectly by?
what are the rate of a chemical reaction depends on?(2)
1) Collision frequency.How often they collide.The more collisions the faster the rate of reactions eg doubling the frequency doubles the rate
2) The energy transferred during a collision.Particles have to collide with enough energy for collision to be successful
what are the four things rate of reactions depend on?
-Temperature
-Surface area
-The presence of a catalyst
-Concentration of solution or pressure in gas
what does increasing the temperature do?(3)
what if a solution is more concentrated?
what happens when the pressure of a gas is increased?
what does increasing the surface area do?and what does it mean?
-When increasing the temperature particles move faster,they collide more frequently,collision will have enough energy to make reactions happen as they move fast (more energy)
-If a solution is more concentrated there are more particles knocking about in the same volume of water,or any solvent
-When the pressure of gas is increased it means that the same number of particles occupies a smaller space.This makes collisions between the reactant particles more frequent
-Increasing the surface area,if one of the reactants is a solid then breaking it up into smaller pieces will increase its surface area to volume ration.This means that for the same volume of a solid the particles around it will have more areas to worm on so there will be collisions more frequently
what is a catalyst?
what are enzymes?
why are the different catalyst needed and how do they do this?
-A catalyst is a substance that speeds up reaction without being used up.This means its not part of the overall reaction equation.
-Different catalyst are needed for different reactions they all work by decreasing the activation energy needed for the reaction to occur.They do this by providing an alternative reaction pathway with a lower activation energy
-Enzymes are biological catalysts they catalyse reactions in living things
