Surface tension for water and mercury

[mary d]

At 20 C degrees the surface tension for water is 73 dyn/cm and mercury is 470 dyn/cm how do I find this value in SI units?

part 2

a small capillary tube of 1mm diameter is placed into a container of 20 degree C will the level of the water in the tube move above or below the level of the water? by what distance in meters? Then how do I calculate the volume and mass in kg of the water being moved up or down. Where do I begin? I know there is a formula how do I find it?

one more really stupid question
what effect does temperature have on surface tension?

 

[arcnets]

part 1

The dyn is the CGS unit of force, so:
1 dyn = 1 g cm s^-2

part 2

The idea is that the water surface inside the tube is not flat. It curves up towards the wall, touching the wall at an angle smaller than 90°. Experiments have shown that for 'water in glass' you may assume 0°, that means the surface being vertical at the wall.
So it's the surface tension that holds the water up. Find the total force by taking into account that the tension acts all around the rim. When you know that force, it should be easy to find how much water can be held up.

part 3

Surface tension goes down as temperature goes up. Because the inter-molecular distance increases.

 

[M98Ranger]

To find the surface tension values for water and mercury in SI units, you can use the conversion factor of 1 dyn/cm = 0.001 N/m. This means that the surface tension for water in SI units is 0.073 N/m and for mercury is 0.47 N/m.

For the second part, the level of the water in the capillary tube will rise above the level of the water in the container due to capillary action. The amount of rise will depend on the diameter of the capillary tube and the surface tension of water. To calculate the distance in meters, you can use the formula h = 2Tcosθ/ρgr, where h is the height of the rise, T is the surface tension, θ is the contact angle, ρ is the density of the liquid, g is the acceleration due to gravity, and r is the radius of the capillary tube.

To calculate the volume and mass of the water being moved, you can use the formula V = πr^2h and m = ρV, where V is the volume, r is the radius of the tube, h is the height of the rise, and ρ is the density of water. These calculations will give you the volume and mass in SI units of meters and kilograms respectively.

Temperature does have an effect on surface tension. As the temperature increases, the intermolecular forces between water molecules decrease, leading to a decrease in surface tension. This is why water droplets tend to spread out on a hot surface rather than form a spherical shape. Conversely, at lower temperatures, the intermolecular forces increase and surface tension increases as well.