Ummmmmm....how do you......?

Question

calculate the volume of a drop?

Answer 1

First, you must figure out the volume of a drop of water (the liquid that you will be given is very similar to water). You will find some calibrated pipettes (plastic droppers with .25, .5, .75, and 1 mL markings). When the level of liquid is at the line at the base of the bulb, there is 1.0 mL of liquid. Be sure that there are no air bubbles. A good way to fill it exactly is to fill it slightly less than 1 mL and then let a couple of air bubbles out and liquid replace it. Repeat this until filled exactly to 1.0 mL.

2. Now count how many drops it takes to completely expel the liquid. Be careful at the end that some apparent bubbles will be mostly air. These can count as a half-drop. Repeat this procedure three times and record the results in your data chart.

3. Your teacher should have come around already and sprinkled some powder over the water in you pizza pan. Do not disturb this water. It must be still to perform the experiment.

4. Your teacher will come by and put a drop of oleic acid solution in the center of your pan. The oleic acid will push the powder out of the way forming a circle. Measure the diameter of the circle in three different places and record the result.



5. Clean up your area and wash the pizza pan well with soap to get all of the oleic acid off.

Data chart:

Drops/mL ________ drops    ________ drops          ________ drops   Average ___________ drops  

Circle Diameter (cm)

1. ___________ cm

2. ___________ cm

3. ___________ cm

Average___________ cm

Calculations:

1. Calculate the volume of one drop of liquid. ___________ mL

2. The oleic acid is not pure. .8 drops of oleic acid were added to 96 drops of alcohol. What percent of the volume is oleic acid? Now multiply the volume of one drop and the percent of oleic acid (converted to a decimal) and find what volume of oleic acid is in one drop.

_____________% oleic acid _____________ volume oleic acid/drop

3. The equation for the volume of a cylinder is V=pr2h. Solve this equation for h.

4. Now use the equation for h, your average diameter (converted to a radius) and your answer to #2 (volume) to find the height of an oleic acid molecule.