Thread: volume/diameter/surface

Completey stuck on this one, anyone able to help please!?

A drop of oil (volume 0.05cm3) Is released from a medicine dropper on a calm surface of a pond where it spreads out to cover an area of 40cm2. Assume that the oil film has a uniform thickness equal to the diameter of an oil molecule. Calculate the diameter of an oil molecule and express your answers in scientific notation to an appropriate number of significant figures.

Originally Posted by Richynic

Completey stuck on this one, anyone able to help please!?

A drop of oil (volume 0.05cm3) Is released from a medicine dropper on a calm surface of a pond where it spreads out to cover an area of 40cm2. Assume that the oil film has a uniform thickness equal to the diameter of an oil molecule. Calculate the diameter of an oil molecule and express your answers in scientific notation to an appropriate number of significant figures.

Volume = area*thickness
=> thickness = volume/area
= 0.05/40 = 0.00125 cm = 1 x 10^-3 cm which is one sig fig, which i think is the correct amount to use here. 0.05 has one sig fig, 40 has 2, i believe the rule is the answer should have as many sig fig's as the quantity with the least sig figs. But i may be wrong.

Use your units as a guide if you don't remember formulas. We know diameter has to be in cm. we are given cm^3 and cm^2, the only way to get cm from those is to divide cm^3 by cm^2.

Thanks for that. You have been most helpful.