a drop of oil (volume 0.05cm3) is released from a medicine dropper on to the 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 answer in scientific notation to an appropriate number of sig. figs.

volume = pi*r^2*thickness
You know volume is 0.05cc.
pi*r^2 is the area and you know that is 40 cm^2
calculate thickness. Watch the number of significant figures. Post your work if you get stuck.

A thin apron is used in dental offices to protect patients from harmful xrays. If the sheet measures 75.0 cm by 55.0 cm by .10cm and the density of lead is 11.3 g/cm3 what is the mass of the apron in grams?

0.05c

To find the diameter of an oil molecule, we need to solve for the thickness of the oil film. We can use the formula for the volume of a cylinder:

volume = π * r^2 * thickness

First, let's solve for the thickness of the oil film. We know that the volume is 0.05 cm^3 and the area is 40 cm^2.

0.05 cm^3 = π * r^2 * thickness

Now, let's solve for the thickness. Divide both sides of the equation by π * r^2:

thickness = 0.05 cm^3 / (π * r^2)

Since we are looking for the thickness in terms of the diameter of an oil molecule, which is equal to two times the radius of an oil molecule, we can express the radius as (diameter/2). Substituting this into the equation:

thickness = 0.05 cm^3 / (π * (diameter/2)^2)

Simplifying further:

thickness = 0.05 cm^3 / (π * (diameter^2) / 4)

Now, we have the equation in terms of the diameter. We can plug in the given values and solve for the diameter of an oil molecule:

thickness = 0.05 cm^3 / (π * (diameter^2) / 4)
40 cm^2 = π * (diameter^2) / 4

Multiply both sides by 4:

160 cm^2 = π * (diameter^2)

Divide both sides by π:

diameter^2 = 160 cm^2 / π

Now, take the square root of both sides to solve for the diameter:

diameter = √(160 cm^2 / π)

Using a calculator and the value of π to an appropriate number of significant figures, we find:

diameter ≈ 0.283 × 10^-4 cm (in scientific notation)

Therefore, the diameter of an oil molecule is approximately 0.283 × 10^-4 cm, expressed in scientific notation to an appropriate number of significant figures.