##### Determine the radius of the capillary tube from the measurements of the surface tension of pure water.

**Calculations:**

Determine the radius of the capillary tube from the measurements of the surface tension of pure water. The radius is calculated using equation (4) and the values of the density and surface tension of water at 25 ⁰C, which are r= 0.9971 g/cm3and g= 72.0 dyne/cm.

Determine the surface tension using equation (4) for all n–butanol solutions.

Density of pure n–butanol is 0.81 g/cm3n–butanol aqueous solutions.Determine the radius of the capillary tube from the measurements of the surface tension of pure water.ange from 0.8350 g/cm3to 0.9550g/cm3, use the average in your calculations: 0.8950 g/cm3

3.Determine the surface tension using equation (4) for all NaCl solutions.The density of the NaCl solutions is almost identical to the density of pure water. Use this value in your calculations for all the NaCl solutions: 1.0111 g/cm3

Plot the surface tension, gvs. In Cand determine the slope for n–butanol solutions and for NaCl solutions (separate plots).

Estimate the excess surface concentration, G, from the slope of gvs. In C and equation (5).Assume the temperature is 298 Kand R = 8.3145 x 103g m2s–2K–1mol–1.The units of the excess surface concentration should be mol/m2.

**Chemicals:**

0.8 M n–butanol

0.8 M NaCl3% Chronic acid

Petroleum jelly