It is possible to measure the rate at which potassium manganate(VII), KMnO₄(aq), Mᵣ = 158, diffuses through a permeable gel using the following method. [Figure 2.1] step 1 A petri dish is prepared with a permeable gel. step 2 A hole of diameter 0.5 cm is cut in the centre of the permeable gel. step 3 A sample of KMnO₄(aq) is placed into the hole and at the same time a stopwatch is started. step 4 After 3 minutes the diameter of the coloured spot is measured and recorded. step 5 The diameter is measured every 3 minutes until there are three successive equal measurements. A student obtained the results shown in Table 2.1. Table 2.1: time /minute | diameter of the coloured spot/cm | diameter increase of the coloured spot/cm 0 | 0.5 | 0.0 3 | 1.1 | 0.6 6 | 1.7 | 1.2 9 | 2.3 | 1.8 12 | 2.7 | 2.2 15 | 3.1 | 2.6 18 | 3.2 | 2.7 21 | 3.7 | 3.2 24 | 3.9 | 3.4 27 | 4.0 | 3.5 30 | 4.1 | 3.6 33 | 4.1 | 3.6 36 | 4.1 | 3.6