Finding reaction rates from graphs

Question 1

How to calculate mean reaction rate from graph

Answer 1

Change in y / total time taken (CHANGE IN X)

Question 2

Find the mean rate of reaction between 20 s and 40 s
20 s goes up to 15 on y axis
40 s goes up to 19 on y axis

Answer 2

19 - 15 / time
40 - 20 = 20 seconds
4 / 20 = 0.2 cm^3/s

Question 3

Drawing tangent to find reaction rate at particular point
Find rate of reaction at 3 min
3 goes up to 1.5 on y axis

Answer 3

You would draw a tangent line on 1.5 and draw a gradient
calculate gradient = change in y / change in x
( 2.2 - 1.4 ) / (5 - 2) = 0.27 g/min