Citrus growers protect their fruit from cold temperatures by spraying them with water which releases energy when it freezes. If the grower sprays 375 g of H2O on the fruit tree, how much energy will be released when the water freezes? ΔHfusion of water is 6.01 kJ/mol

Dissolving 3.0 g of CaCl2(s) in 150.0 g of water in a calorimeter (Figure 5.12) at 22.4 °C causes the temperature to rise to 25.8 °C. What is the approximate amount of heat involved in the dissolution, assuming the specific heat of the resulting solution is 4.18 J/g °C? Is the reaction exothermic or endothermic?

Cooking A cook prepares a solution for boiling by adding12.5 g of NaCl to a pot holding 0.750 L of water. Atwhat temperature should the solution in the pot boil?Use Table 14.5 for needed data.

Consider two hypothetical pure substances, AB(s) and XY(s). When equal molar amounts of these substances are placed in separate 500-mL samples of water, they undergo the following reactions: AB(s)A+(aq)+B(aq)XY(s)XY(aq) a Which solution would you expect to have the lower boiling point? Why? b Would you expect the vapor pressures of the two solutions to be equal? If not, which one would you expect to have the higher vapor pressure? c Describe a procedure that would make the two solutions have the same boiling point. d If you took 250 mL of the AB(aq) solution prepared above, would it have the same boiling point as the original solution? Be sure to explain your answer. e The container of XY(aq) is left out on the bench top for several days, which allows some of the water to evaporate from the solution. How would the melting point of this solution compare to the melting point of the original solution?

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.

Consider the following aqueous solutions: (i) 0.20 m HOCH2CH2OH (nonvolatile, nonelectrolyte); (ii) 0.10 m CaCl2 (iii) 0.12 m KBr; and (iv) 0.12 m Na2SO4. (a) Which solution has the highest boiling point? (b) Which solution has the lowest freezing point? (c) Which solution has the highest water vapor pressure?

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.

The solubility of NaCl in water at 100 C is 39.1 g/100. g of water Calculate the boiling point of this solution. (Assume i = 1.85 for NaCl.)

Two samples of sodium chloride solutions are brought to a boil on a stove. One of the solutions boils at 100.10C and the other at 100.15C. a Which of the solutions is more concentrated? b Which of the solutions would have a lower freezing point? c If you split the solution that boils at 100.1C into two portions, how would the boiling points of the samples compare? Which of the following statements do you agree with regarding the determination of your answer for part c? I. The question cannot be answered with certainty without knowing the volumes of each portion. II. Making the necessary assumption that the two samples have equal volumes, I was able to correctly answer the question. III. The volumes that the sample was split into are irrelevant when determining the correct answer.

How much N2 can dissolve in water at 25 C if the N2 partial pressure is 585 mm Hg?