. When 13.46 g of lactic acid, C3H6O3, are mixed with 119 g of stearic acid, the mixture freezes at 62.7 degrees C. The freezing point of pure stearic acid is 69.4 °C. What is the freezing point constant of stearic acid

6-111 As noted in Section 6-8C, the amount of external pressure that must be applied to a more concentrated solution to stop the passage of solvent molecules across a semipermeable membrane is known as the osmotic pressure The osmotic pressure obeys a law similar in form to the ideal gas law (discussed in Section 5-4), where Substituting for pressure and solving for osmotic pressures gives the following equation: RT MRT, where M is the concentration or molarity of the solution. (a) Determine the osmotic pressure at 25°C of a 0.0020 M sucrose (C12H22O11) solution. (b) Seawater contains 3.4 g of salts for every liter of solution. Assuming the solute consists entirely of NaCl (and complete dissociation of the NaCI salt), calculate the osmotic pressure of seawater at 25°C. (c) The average osmotic pressure of blood is 7.7 atm at 25°C. What concentration of glucose (C6H12O6) will be isotonic with blood? (d) Lysozyme is an enzyme that breaks bacterial cell walls. A solution containing 0.150 g of this enzyme in 210. mL of solution has an osmotic pressure of 0.953 torr at 25°C. What is the molar mass of lysozyme? (e) The osmotic pressure of an aqueous solution of a certain protein was measured in order to determine the protein's molar mass. The solution contained 3.50 mg of protein dissolved in sufficient water to form 5.00 mL of solution. The osmotic pressure of the solution at 25°C was found to be 1.54 torr. Calculate the molar mass of the protein.

Refer to Figure 13.10 ( Sec. 13-4b) to answer these questions. (a) Does a saturated solution occur when 65.0 g LiCl is present in 100 g H2O at 40 C? Explain your answer. (b) Consider a solution that contains 95.0 g LiCl in 100 g H2O at 40 C. Is the solution unsaturated, saturated, or supersaturated? Explain your answer. (c) Consider a solution that contains 50. g Li2SO4 in 200. g H2O at 50 C. Is this solution unsaturated, saturated, or supersaturated? Explain your answer. Figure 13.10 Solubility of ionic compounds versus temperature.

The freezing point of a 0.21 m aqueous solution of H2SO4 is -0.796C. (a) What is i? (b) Is the solution made up primarily of (i) H2SO4 molecules only? (ii) H+ and HSO4- ions? (iii) 2H+ and 1SO42- ions?

Fluoridation of city water supplies has been practiced in the United States for several decades. It is done by continuously adding sodium fluoride to water as it comes from a reservoir. Assume you live in a medium-sized city of 150,000 people and that 660 L (170 gal) of water is used per person per day. What mass of sodium fluoride (in kilograms) must be added to the water supply each year (365 days) to have the required fluoride concentration of 1 ppm (part per million)that is, 1 kilogram of fluoride per 1 million kilograms of water? (Sodium fluoride is 45.0% fluoride, and water has a density of 1.00 g/cm3.)

Calculate the molality of a solution made by dissolving 115.0 g ethylene glycol, HOCH2CH2OH, in 500. mL water. The density of water at this temperature is 0.978 g/mL. Calculate the molarity of the solution.

A 0.109 mol/kg aqueous solution of formic acid, HCOOH, freezes at −0.210 °C. Calculate the percent dissociation of formic acid.

The dispersed phase of a certain colloidal dispersion consists of spheres of diameter 1.0 102 nm. (a) What are the volume (V=43r2) and surface area (A = r2) of each sphere? (b) How many spheres are required to give a total volume of 1.0 cm3? What is the total surface area of these spheres in square meters?

Maple syrup sap is 3% sugar (sucrose) and 97% water bymass. Maple syrup is produced by heating the sap toevaporate a certain amount of the water. (a) Describe what happens to the composition and boilingpoint of the solution as evaporation takes place. (b) A rule of thumb among maple syrup producers is thatthe finished syrup should boil about 4 C higher than theoriginal sap being boiled. Explain the chemistry behindthis guideline. (c) If the finished product boils 4 C higher than the originalsap, calculate the concentration of sugar in the finalproduct. Assume that sugar is the only solute and theoperation is done at 1 atm pressure.

Predict the relative solubility of each compound in the two solvents, based on the intermolecular attractions. (a) Is potassium iodide more soluble in water or in methylene chloride (CH2Cl2)? (b) Is toluene (C6H5CH3) more soluble in benzene (C6H6) or in water? (c) Is ethylene glycol (C2H4(OH)2) more soluble in hexane (C6H14) or in ethanol (C2H5OH)?