(a)
Interpretation: The molality of the ethanol in a mixture of ethanol and water has to be identified.
Concept introduction:
Freezing point depression: The freezing point of the solution varies with the solute concentration.
Weight percent: The mass of one component divided by the total mass of the mixture, multiplied by
(b)
Interpretation: The weight percentage of the ethanol in a mixture of ethanol and water has to be identified.
Concept introduction:
Weight percent: The mass of one component divided by the total mass of the mixture, multiplied by
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Chapter 13 Solutions
Chemistry & Chemical Reactivity
- Insulin is a hormone responsible for the regulation of glucose levels in the blood. An aqueous solution of insulin has an osmotic pressure of 2.5 mm Hg at 25C. It is prepared by dissolving 0.100 g of insulin in enough water to make 125 mL of solution. What is the molar mass of insulin?arrow_forward6-111 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.arrow_forwardFluoridation 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.)arrow_forward
- Will red blood cells crenate, hemolyze, or remain unaffected when placed in each of the solutions in Problem 8-107?arrow_forwardCalcium chloride, CaCl2, has been used to melt ice from roadways. Given that the saturated solution is 32% CaCl2 by mass, estimate the freezing point.arrow_forward6-20 Give a familiar example of solutions of each of these types: (a) Liquid in liquid (b) Solid in liquid (c) Gas in liquid (d) Gas in gasarrow_forward
- What quantity of ethylene glycol, HOCH2CH2OH, must be added to 125 g of water to raise the boiling point by 1.0 C? Express the answer in grams.arrow_forwardCalculate 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.arrow_forwardThe 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?arrow_forward
- 6-113 List the following aqueous solutions in order of decreasing freezing point: 0.040 M glycerin (C3H8O3) 0.025 M NaBr, and 0.015 M AI(NO3)3 Assume complete dissociation of any salts.arrow_forwardThe density of a 3.75 M aqueous sulfuric acid solution in a car battery is 1.225 g/mL. Express the concentration of the solution in molality, mole fraction H2SO2, and mass percentage of H2SO4.arrow_forwardThe 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?arrow_forward
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