Instruction for Surface Tension Experiment

  1. Follow the procedure for the Wihelmy Slide method given in Experiment 16 in the book by Halpern and mcBane.  Use the attachment method for all measurements.

  2. Measure the value of the correction constant C using water as a reference.  Make several (4-5) measurements.    Calculate the average value  of mmax , and its standard deviation.  Use the average values of mmax to calculate the average values of C and its standard deviations.

  3. Prepare aqueous solutions of NaCl, acetone and sodium dodecyl sulfate (SDS), as described in Halpern and Mcbane. 

  4. measure the surface tension of each of the solutions prepared in step 3.  For each solution make several measurements of mmax  and calculate the average surface tension and its standard deviation.

  5. Use Excel for all calculations and graphs.  Plot the surface tension versus concentration for each solution system.  Include error bars equal to +/- one standard deviation for each point. Error bars can be added to a graph in Excel by including the standard deviation of each y value in the spreadsheet, right clicking on the graph and selecting   "format data series",  followed by "Y error bars", followed by "display both", followed by "custom option".  Under "custom option"  enter the series corresponding to the standard deviation data in both the "+" and "-" boxes.

  6. Summarize the effect of each of the solutes, NaCl, acetone and SDS on the surfaces tension of water.

  7. Compare your results with values from the literature, if possible.