Kinetics Flashcards
formula for reaction rate
The change in concentration/ amount of a reactant or product over time
Give the formula for the rate of reaction
Amount of reactant used or product formed/ time
Do particles react every time they collide?
No
What conditions allow particles to react and what theory is this called?
• They must collide in the right direction, and need to be facing the right way
• Collide with a certain minimum amount of kinetic energy
• Collision theory
What is activation energy
The minimum amount of kinetic energy that particles need to react
How does a reaction start?
By breaking bonds
How do particles receive extra energy
By heating them
Do molecules in a gas all have the same amount of energy?
No
What is variation of energy of particles in a gas
• Some molecules move slowly, don’t have much kinetic energy
• Most molecules are moving at a moderate speed, their energies are somewhere in the middle
• Some have loads of energy
What is the graph for representing number of moles of gas over different kinetic energies
Maxwell-Boltzmann distribution
The area under the maxwell-Boltzmann distribution curve is called what?
The total number of molecules
What does the peak of the curve represent?
The most probable energy. Emp
Where can the mean average energy of all the molecules be found in the graph
To the right of the peak
Why does the curve start at (0,0)
Because no molecules have zero energy
Why is there an area called Ea
Because some molecules have more than the activation energy, tgeee are the only ones that can react
List the factors that increase the rate of reaction
• Increasing temperature
• Increasing concentration
• Increasing pressure
• Catalysts
How does increasing the temperature, increase the rate of reaction
• More particles have kinetic energy
• And will move faster
• Greater proportion will have the activation energy
•Changes the shape of the maxwell-Boltzmann curve, pushes it further to the right
• Collide more often
• Small increases in temperature can lead to quite large increases in reaction rates
Define a catalyst
A substance that increases the rate of a reaction by providing an alternative reaction pathway with a lower activation energy. The catalyst is chemically unchanged at the end of the reaction but do take part in the reactions
Only work on a single reaction
Catalysts
How do catalysts save money in the industrial process?
Allow you to make the product faster at a lower temperature
How can you measure the rate of reaction
How fats the reactants are used up or how fats products are formed
What three ways are there to measure a reaction rate
• Timing how long it takes for a precipitate to form
• Measuring a decrease in mass
• Measuring the volume of gas given off
How do you measure the amount of gas given off
• Using a gas syringe
• Accurate
• Measure the volume of gas being produced
How do you measure a decrease in mass?
• Product must be a gas
• Measure formation using a mass balance
• As gas is given off, the reaction mixture decreases
• Done on a fine cupboard
• Accurate
Give an example of measuring reaction rates
The reaction between sodium thiosulphate and hydrochloride acid
What is the purpose of this reaction example?
To demonstrate the effect of increasing temperature on reaction rates
Give 2examples of dependent/controlled variables in this reaction
• The depth of the liquid
• the concentration of solutions
What is the effect of increasing the concentration and the pressure of a reaction
• Increases rate of reaction
• Particles will be closer to each other
• They’ll collide more often
• Frequent successful collisions means more chances they they will react
Explain why an increase in temperature increases the rate at which this gas decomposes
• An increase in the number of particles with activation energy
• More successful collisions at a given time
