menu search
brightness_auto
more_vert

Why two or more mercury drops form a single drop when brought in contact with each other?

thumb_up_off_alt 0 like thumb_down_off_alt 0 dislike

1 Answer

more_vert
 
verified
Best answer
  • A spherical shape has the minimum surface area-to-volume ratio of all geometric forms.
  • When two drops of a liquid are brought in contact, the cohesive forces between their molecules coalesces the drops into a single larger drop.
  • This is because, the volume of the liquid remaining the Same, the surface area of the resulting single drop is less than the combined surface area of the smaller drops.
  • The resulting decrease in surface energy is released into the environment as heat.

Proof : Let n droplets each of radius coalesce to form a single drop of radius R. As the Volume of the liquid remains constant,

volume of the drop = volume of n droplets

\(\frac{4}{3}πR^3\) = \(n × \frac{4}{3}πr^3\)

∴ R3=nr3

\(∴ R =\sqrt[3]{n}\,r\) ....(1)

Surface area of n droplets =n × 4πr2

Surface area of the drop = 4πR2 = 4π×n2/3r2 ..... from eq. 1

∴ Surface area of the drop = n2/3 × 4πr2

∴ The change in the surface area

= surface area of drop — surface area of n droplets

= 4πr2 (n2/3 — n)

Since the bracketed term is negative, there is a decrease in surface area and a decrease in surface energy. .

thumb_up_off_alt 0 like thumb_down_off_alt 0 dislike

Related questions

thumb_up_off_alt 0 like thumb_down_off_alt 0 dislike
1 answer

Subscribe to our Youtube Channel

For amazing tutorial videos, podcasts, hindi tutorials

thumb_up_off_alt 0 like thumb_down_off_alt 0 dislike
1 answer

4.1k questions

3.6k answers

50 comments

376 users

...