# The surface tension of benzene at 20°C is 28.85 dyne/cm. In a capillary apparatus the liquid rose to a height of 1.832 cm. The density of benzene is 0.8765 g/mL. How would you calculate the diameter of the capillary tube in mm?

##### 1 Answer

The diameter of the capillary tube is 0.366 mm.

#### Explanation:

One method for measuring the surface tension of a liquid is to measure the height the liquid rises in a capillary tube.

The formula is

#color(blue)(|bar(ul(color(white)(a/a) h = "2γcosθ"/"ρgr" color(white)(a/a)|)))" "#

where

We can rearrange the equation to get

#color(blue)(|bar(ul(color(white)(a/a) r = "2γcosθ"/(hgρ)color(white)(a/a)|)))" "#

For most liquids and clean glass, the contact angle

If

#color(blue)(|bar(ul(color(white)(a/a) r = "2γ"/(hgρ)color(white)(a/a)|)))" "#

In your problem,