Rate of reaction - OZ

Question 1

Factors that affect rate

Answer 1

temp, pressure, concentration, catalyst

Question 2

What is the collision theory

Answer 2

for a chemical reaction to occur:
particles must collide and the collision must have energy exceeding the activation energy for the reaction. The collision must have the correct orientation for particles to react

Question 3

What is the kinetic theory

Answer 3

raising the temperature causes particles to move faster and gain kinetic energy so sufficient activation energy is met. Activation energy is the minimum amount of energy required for a reaction to occur

Question 4

What is the particle theory

Answer 4

all materials are made out of particles - in chemical reaction particles can be atoms, molecules, ions or sometimes electrons. If we increase the number of particles in a volume it increases frequency of collisions per unit time

Question 5

Enthalpy diagram of exothermic reaction with/without catalyst

Answer 5

https://bam.files.bbci.co.uk/bam/live/content/z2ffpbk/large

Question 6

Enthalpy diagram of endothermic reaction with/without catalyst

Answer 6

https://www.docbrown.info/page03/3_31rates/Image35.gif

Question 7

How to monitor chemical reactions when gas is produced

Answer 7

you can monitor the volume over time

Question 8

How to monitor chemical reactions when a precipitation is produced

Answer 8

you can monitor how light levels are transmitted through the liquid or become opaque

Question 9

How to monitor chemical reactions when acid is produced

Answer 9

pH

Question 10

How to find the initial rate of reaction of a graph

Answer 10

draw a tangent from the start and make the largest triangle so it is more accurate and find the gradient of the tangent (Δy/Δx)

Question 11

How is rate affected when temperature is increased

Answer 11

rate increases when temperature increases as particles have more kinetic energy so more frequent collisions occur with sufficient activation energy per unit time. This can be seen in the Maxwell-Boltzmann distribution as the curve shifts to the left so there is more area under the graph after the activation energy

Question 12

Maxwell-Boltzmann distribution of increased temperature

Answer 12

https://www.chemistrystudent.com/images/ASPhysical/kinetics/maxwell-boltzmann2.png

Question 13

How is rate affected when a catalyst is added

Answer 13

it increases rate because it provides an alternative route with a lower activation energy so there are a higher frequency of particles with suffient activation energy which their collisions result in a reaction occuring. This is shown on the Maxwell-Boltzmann distribution as the activation energy is shifted to the left so a larger area is under the graph.

Question 14

Maxwell-Boltzmann distribution with catalyst

Answer 14

https://www.chemistrystudent.com/images/ASPhysical/kinetics/maxwell-boltzmann4.png

Question 15

What is a catalyst

Answer 15

something that increases rate of reaction by providing an alternative route with a lower activation energy but it doesn’t get used up

Question 16

How can a conical flask and gas syringe be used to find the initial rate of a reaction

Answer 16

reactants are placed in the conical flask and a bung is immediately placed on
with the syringe set to 0, after bung is placed a timer is started
every 15 sec the volume of gas in syringe is recorded
the recordings can be plotted on a graph with vol of gas against time
a line of best fit is drawn then a tangent starting from the start is drawn
the gradient is found using (Δy/Δx)