Kinetics

Question 1

formula for reaction rate

Answer 1

The change in concentration/ amount of a reactant or product over time

Question 2

Give the formula for the rate of reaction

Answer 2

Amount of reactant used or product formed/ time

Question 3

Do particles react every time they collide?

Answer 3

No

Question 4

What conditions allow particles to react and what theory is this called?

Answer 4

• 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

Question 5

What is activation energy

Answer 5

The minimum amount of kinetic energy that particles need to react

Question 6

How does a reaction start?

Answer 6

By breaking bonds

Question 7

How do particles receive extra energy

Answer 7

By heating them

Question 8

Do molecules in a gas all have the same amount of energy?

Answer 8

No

Question 9

What is variation of energy of particles in a gas

Answer 9

• 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

Question 10

What is the graph for representing number of moles of gas over different kinetic energies

Answer 10

Maxwell-Boltzmann distribution

Question 11

The area under the maxwell-Boltzmann distribution curve is called what?

Answer 11

The total number of molecules

Question 12

What does the peak of the curve represent?

Answer 12

The most probable energy. Emp

Question 13

Where can the mean average energy of all the molecules be found in the graph

Answer 13

To the right of the peak

Question 14

Why does the curve start at (0,0)

Answer 14

Because no molecules have zero energy

Question 15

Why is there an area called Ea

Answer 15

Because some molecules have more than the activation energy, tgeee are the only ones that can react

Question 16

List the factors that increase the rate of reaction

Answer 16

• Increasing temperature
• Increasing concentration
• Increasing pressure
• Catalysts

Question 17

How does increasing the temperature, increase the rate of reaction

Answer 17

• 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

Question 18

Define a catalyst

Answer 18

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

Question 19

Only work on a single reaction

Answer 19

Catalysts

Question 20

How do catalysts save money in the industrial process?

Answer 20

Allow you to make the product faster at a lower temperature

Question 21

How can you measure the rate of reaction

Answer 21

How fats the reactants are used up or how fats products are formed

Question 22

What three ways are there to measure a reaction rate

Answer 22

• Timing how long it takes for a precipitate to form
• Measuring a decrease in mass
• Measuring the volume of gas given off

Question 23

How do you measure the amount of gas given off

Answer 23

• Using a gas syringe
• Accurate
• Measure the volume of gas being produced

Question 24

How do you measure a decrease in mass?

Answer 24

• 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

Question 25

Give an example of measuring reaction rates

Answer 25

The reaction between sodium thiosulphate and hydrochloride acid

Question 26

What is the purpose of this reaction example?

Answer 26

To demonstrate the effect of increasing temperature on reaction rates

Question 27

Give 2examples of dependent/controlled variables in this reaction

Answer 27

• The depth of the liquid
• the concentration of solutions

Question 28

What is the effect of increasing the concentration and the pressure of a reaction

Answer 28

• 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

Question 29

Explain why an increase in temperature increases the rate at which this gas decomposes

Answer 29

• An increase in the number of particles with activation energy
• More successful collisions at a given time