Which Diffuses Faster? Potassium or Sodium?

2015-01-23

[public] 3.93K views, 78.0 likes, 2.00 dislikes audio only

I do a quick experiment to see which ion diffuses faster.

Identical vials filled with Phenolphthalein solution.
/youtube/video/HjPon34548o?t=0

2 drops of 3 molar sodium hydroxide solution is added to the left vial
/youtube/video/HjPon34548o?t=5

and 2 drops of 3 molar potassium hydroxide to the right one.
/youtube/video/HjPon34548o?t=8

The glass tubes pipe the solution to the bottom of the vial without mixing.
/youtube/video/HjPon34548o?t=11

The salt diffuses upwards; made visible by the phenolphthalein.
/youtube/video/HjPon34548o?t=17

Images are 20-30 minutes apart.
/youtube/video/HjPon34548o?t=22

It looks like sodium diffuses faster than potassium; perhaps due to lower mass and smaller atomic size.
/youtube/video/HjPon34548o?t=27