Number of drops Water Trial 1: Average: Questions: a. What ratio of surface tens
ID: 141141 • Letter: N
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Number of drops Water Trial 1: Average: Questions: a. What ratio of surface tensions do you calculate between water and alcohol using the above data? 55:00 b. How does this compare to the results obtained with the first method? c. Explain why both methods are essentially the same. Part C- Capillary - rise method Object: The surface tension of a liquid can be determined by the height to which a solution rises in a capillary tube which the liquid wets (e.g. glass). The following equation gives the surface tension: Surface tension (in dynes per cm.)-1/2 hdgr Where h height the liquid rises in the capillary (in cm.) d density of liquid (1.0 for water; 0.79 for alcohol) g gravitational constant (981 dynes at sea level) r radius of capillary tube 94 Hold the end of a capillary tube vertically in a petri dish of distilled water and measure the height of the liquid in the tube. Repeat with 95% ethyl alcohol after rinsing the same capillary tube twice with alcohol. Procedure: Water Alcohol Questions: Use the above equations to determine the surface tension of water and alcohol in dynes per cn. a. Bio 205 page 3Explanation / Answer
Surface tension of water =1/2hgdr
= 1/2 ×1.95×981×0.04×1
=38.2
Surface tension of alcohol = 1/2 hgdr
= 1/2 ×1.2×981×0.79×.04
=18.59
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