00:01
For this question, we need to carry out a unit conversion calculation.
00:04
They tell us that the diameter is 2 .00 nanometers, so let's first convert that into centimeters, 2 .00 nanometers, where nano means 10 to the negative 9, so 1 nanometer is 1 times 10 to the negative 9 meters, and then 1 meter is 100 centimeters, so we've got 2 .00 times 10 to the negative 7 centimeters.
00:45
The volume of the nanoparticle then will be equal to four -thirds pi r cubed, so it'll be four -thirds 3 .14 times r, which is the diameter, 2 .00 times 10 to the negative 7 centimeters divided by 2, radius being equal to diameter divided by 2, and then we need to cube that, and we get 4 .186, 4 .19 times 10 to the negative 21 centimeters cubed, or milliliters, so knowing that that's our volume, 4 .18 or 4 .19 times 10 to the negative 21 milliliters, we can then use density to get the mass.
01:55
They tell us the density is 19 .3 grams per milliliter...