Osmotic pressure seawater has a salinity of 3.5% meaning that if you boil away a kilogram of seawater, there will be 35g of solids (mostly nacl). when dissolved, the sodium chloride dissociates into separate na+ and clions. a) calculate the osmotic pressure difference between seawater and fresh water. for simplicity, assume that all the dissolved salts in seawater are nacl. b) reverse osmosis occurs when you apply a pressure difference greater than the osmotic pressure to a solution separated from a pure solvent by a membrane permeable only to the solvent. in this process, the solvent flows out of the solution and this can be used to desalinate sea water. use your result from part (a) to find the minimum work required to desalinate one liter of water. c) it is also possible to desalinate water by evaporation. the water vapor is recondensed and the salt is left behind. compare your result from part (b) with the amount of heat that would be required to evaporate a liter of water. assume that the water starts at a temperature of 300 k and the latent heat of vaporization at a pressure of one atmosphere is 40.7 kj/mol. compare your result with that of part (b).

Two identical 82 mg dust particles very far apart (pee 0) are moving directly toward each other at a speed of 3698 m/s. the charge on each is-719 ? c. determine how close they will get to each other. let k = 9x109 n-m2/c2 & ignore gravity.

Use the frequency histogram to complete the following parts. ​(a) identify the class with the​ greatest, and the class with the​ least, relative frequency. ​(b) estimate the greatest and least relative frequencies. ​(c) describe any patterns with the data. female fibula lengths 30.5 31.5 32.5 33.5 34.5 35.5 36.5 37.5 38.5 39.5 0 0.05 0.1 0.15 0.2 0.25 length (in centimeters) relative frequency a histogram titled "female fibula lengths" has a horizontal axis labeled "length in centimeters" from 30.5 to 39.5 in increments of 1 and a vertical axis labeled "relative frequency" from 0 to 0.25 in increments of 0.05. the histogram contains vertical bars of width 1, where one vertical bar is centered over each of the horizontal axis tick marks. the approximate heights of the vertical bars are listed as follows, where the label is listed first and the approximate height is listed second: 30.5, 0.02; 31.5, 0.04; 32.5, 0.05; 33.5, 0.13; 34.5, 0.22; 35.5, 0.25; 36.5, 0.13; 37.5, 0.06; 38.5, 0.09; 39.5, 0.01. ​(a) the class with the greatest relative frequency is nothing to nothing centimeters. ​(type integers or decimals. do not round. use ascending​ order.)

An object with initial temperature 130 ∘ f is submerged in large tank of water whose temperature is 50 ∘ f . find a formula for f ( t ) , the temperature of the object after t minutes, if the cooling constant is k = − 0.2 . remember newton's law of cooling (the rate of change of temperature with respect to time is equal to k times the difference between the temperature of the object and the surrounding temperature) ! : )