A student made a dropper for which the volume added of 100 drops was equal to 0.

Question

A student made a dropper for which the volume added of 100 drops was equal to 0.98 mL.  

The solution used was 0.50 % (by volume) oleic acid.

Show full calculation, with units and sig figs.

One of the above drops was used to create a film with a surface area of 109 cm2.  Assume the film is a very wide but short cylinder, therefore  

volume of this film = (surface area) x (thickness)

Note: The film is created by only the oleic acid in the drop, the remainder of the drop is ethanol, which dissolves into the water.  Also remember that 1 mL = 1 cm3.

(c)  Use the volume from 1b and the surface area given to calculate the thickness of the film in cm.   Show full calculation, with units and sig figs.

Explanation / Answer

a) volume of 100 drops = 0.98 mL.

vol of 1 drop = 0.98/100 = 0.0098 mL

b) volume of oleic acid contained in one drop = vol of 1 drop * (% vol of oleic acid)

= 0.0098 * 0.0050 = 0.000049 mL

c) since

volume of this film = (surface area) x (thickness) = vol of one drop = 0.0098 cm3

thk = 0.0098/109 = 8.99x10-5 cm

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.