Arrhenius plots

Question 1

y axis

Answer 1

lnk

Question 2

x axis

Answer 2

1/ T (temperature)

Question 3

Type of graph for Arrhenius plots

Answer 3

Straight line graph

Question 4

Point of Arrhenius plots

Answer 4

Shows how rate constant varies with temperature and activation energy

Question 5

Important about straight line graphs and Arrhenius plots?

Answer 5

we can make the simplified Arrhenius equation in the form of the straight line graph formula
y = mx + c

Question 6

Link simplified Arrhenius equation with y = mx + c

Answer 6

lnk = -Ea x 1 + lnA
/R /T

Question 7

What is the gradient ?

Answer 7

-Ea/R

Question 8

What is the gradient ?

Answer 8

-Ea/RT

Question 9

How can we split -Ea/RT in the straight line graph?

Answer 9

Into -Ea/R = gradient
Into 1/T = x axis

Question 10

Y intercept

Answer 10

lnA
Arrhenius constant

Question 11

How to calculate Ea

Answer 11

gradient = -Ea/R
Calculate gradient of straight line
Rearrange: -gradient multiplied by gas constant !

Question 12

Once we have the gradient how can we calculate the Ea?

Answer 12

-gradient x gas constant
(NEGATIVE GRADIENT)

Question 13

Activation energy units

Answer 13

J per mol

Question 14

What do we need to do to calculate A (Arrhenius constant)?

Answer 14

Pick points on graph to get a set of co-ords, y value is lnk and x value is 1/T
Substitute into equation

Question 15

From the coords: what is y co ord?

Answer 15

lnk

Question 16

From the co odds, what is the x co ord?

Answer 16

1/T

Question 17

Re arrange the equation to find A

Answer 17

lnA = lnk + [(Ea/R) x (1/T)]
Plug values of the gradient and co rods to work out the value of A
Remove the ln: use the e (exponential function) on the value of lnA