Question

If a crystal of potassium permanganate is placed on agar and after 15 minutes the diameter of the area over which the dye has spread is 15 mm, the average diffusion rate is

Answer 1

Answer:

Diffusion rate is 1.96 × $10^{-3}$ $cm^{2}$/s

Explanation:

Diffusion is the process in which the molecules of a substance propagates from a region of higher concentration to region of lower concentration through a semi-permeable membrane.

diffusion rate = $\frac{area}{time}$

Given that; diameter = 15 mm, time = 15 minutes.

The dye spread in a circular form, so that;

area = $\pi$$r^{2}$

r = $\frac{diameter}{2}$ = $\frac{15}{2}$ = 7.5 mm = 0.75 cm

area = $\frac{22}{7}$ × $(0.75)^{2}$ = 1.7679 $cm^{2}$

time = 15 minutes = 15 × 60 = 900 seconds

So that;

diffusion rate = $\frac{1.7679}{900}$

                      = 0.0019643 $cm^{2}$/s

Diffusion rate is 1.96 × $10^{-3}$ $cm^{2}$/s