5.1.1 How Fast?

Question 1

What is the rate equation? include the one for units

Answer 1

rate= change in concentration / time

so rate = moldm^-3 / s = moldm^-3s^-1

k = [A]^m [B]^n where m or n are values 0, 1 or 2

Question 2

define rate of reaction

Answer 2

the change in concentration of reactants/products over time

Question 3

define the term order of reaction

Answer 3

The power to which its concentration is raised in the rate equation.

Question 4

Define the term overall order of reaction

Answer 4

The sum of the individual orders of reaction

Question 5

Define the term half-life

Answer 5

the time it takes for the concentration of a substance to fall to half of its original value

Question 6

Define the term Rate determining step

Answer 6

the slowest step of a chemical reaction that determines the speed (rate) at which the overall reaction proceeds

Question 7

Draw concentration time graphs of the 0, 1st and 2nd orders of reaction

Answer 7

Answer: https://docs.google.com/document/d/1CblPXrp88a_-JekKN5n-UPfxsplHMgo0fUbm6bZZ1CE/edit?usp=sharing

Question 8

how do you find the rate of reaction on a concentration-time graph?

Answer 8

find the gradient of the tangent on the point you are trying to find the rate at

Question 9

draw concentration rate graphs for 0, 1st and 2nd orders of reaction

Answer 9

Answer: https://docs.google.com/document/d/1CblPXrp88a_-JekKN5n-UPfxsplHMgo0fUbm6bZZ1CE/edit?usp=sharing

Question 10

what is the are the successive half life rules for concentration time graphs for each order of reaction?

Answer 10

0 order: successive half lives decrease
1st order: successive half lives stay constant (most likely in exam)
2nd order: successive half lives increase

Question 11

how do you determine the rate constant from the half life?

Answer 11

mathematical term : Ln (can be found on mathematical calculator)
notation for half life: t1/2

k= Ln2 / t1/2

Question 12

define rate constant

Answer 12

a number that converts between the rate of reaction and the concentration and orders of reaction

Question 13

what is the only thing that affects the rate constant and why?

Answer 13

Temperature increase, increases rate because it makes the exponential in the Arrhenius equation negative, and so increases the value of k

Question 14

how do you find a rate equation from the rate determining step?

e.g. if the rate determining step was

XN2O2 +YH2 –> H2O + N2O

Answer 14

you substitute the reactants from the rate determining step into the rate equation
e.g.
XN2O2 +YH2 –> H2O + N2O

rate equation => rate= k [N202]^X [H2]^Y