When a thin glass tube is put into water, the water rises 1.4 cm . When the same tube is put int

step 1 Okay, so now we're working on problem 52 of chapter 11. This problem asks you to explain an occu

When a thin glass tube is put into water, the water rises...

Key Concepts

Capillary Action

Capillary action is the phenomenon where a liquid moves up or down within a narrow tube due to the balance of forces between adhesion to the tube surface and cohesion within the liquid. This effect is observed when the adhesive forces between the liquid and the tube wall are strong enough to overcome the gravitational pull on the liquid.

Surface Tension

Surface tension is the property of a liquid surface that allows it to resist an external force due to the cohesive nature of its molecules. It plays a crucial role in capillary action, as it helps form a curved meniscus, contributing to the rise of the liquid in the tube.

Contact Angle

The contact angle is the marker of the interaction between a liquid and a solid surface, indicating how well the liquid wets the surface. A lower contact angle suggests better wetting and a higher rise of the liquid in the tube, while a higher contact angle indicates poorer wetting and results in lower capillary rise.

Adhesive and Cohesive Forces

Adhesive forces are the attractions between different substances (liquid and solid surfaces) and cohesive forces are the attractions among the molecules in the liquid itself. The interplay between these forces determines how much the liquid will climb the wall of the tube, influencing the height of the capillary rise.

Transcript

00:08 Okay, so now we're working on problem 52 of chapter 11.

00:12 This problem asks you to explain an occurrence that has to do with surface tension and it's balanced between cohesive forces.

00:26 Okay, so when a thin glass tube was put into water the water rises 1 .4 centimeters when the same tube is put into hexane the hexane rises only 0 .4 centimeters so you need to explain why that is so turns out that that first look at both molecules we're talking about.

00:46 So the first one is water.

00:49 So what does water look like? water looks like this.

00:58 I'll kind of crude drawing here, but has an oxygen and a hydrogen and another hydrogen.

01:06 Okay.

01:06 So now in order to see what this kind of means, you'll have to take another water molecule and place it kind of in contact in this general area to compare what they do with one other.

01:17 So one thing that water has, that hexane doesn't have, is hydrogen bonding.

01:23 So i'll put another one here.

01:32 Turn off that into shape.

01:36 It'll help better.

01:37 Ok.

01:38 So now, when you have two different water molecules sitting in the same canvas, you can see that you can have hydrogen bonding going on.

01:49 Let me see if i can clarify.

01:55 So just as a demonstration, this is probably not a very good configuration of molecules, but you can see that the oxygen and a hydrogen, they form these directional hydrogen bonds.

02:06 And the other force that is attracting molecules together in all in every, every type of liquid is dispersion forces...

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