Solution Exam



Solution Exam

Form A

Directions: Choose the best answer.

1. The molality of the glucose in a 1.0-molar glucose solution can be obtained by using which of the following?

(A) Volume of the solution

(B) Temperature of the solution

(C) Solubility of glucose in water

(D) Degree of dissociation of glucose

(E) Density of the solution

2. A student wishes to prepare 2.00 liters of 0.100-molar KIO3 (molecular weight 214). The proper procedure is to weigh out

(A) 42.8 grams of KIO3 and add 2.00 kilograms of H2O

(B) 42.8 grams of KIO3 and add H2O until the final homogeneous solution has a volume of 2.00 liters

(C) 21.4 grams of KIO3 and add H2O until the final homogeneous solution has a volume of 2.00 liters

(D) 42.8 grams of KIO3 and add 2.00 liters of H2O

(E) 21.4 grams fo KIO3 and add 2.00 liters of H2O

3. The weight of H2SO4 (molecular weight 98.1) in 50.0 milliliters of a 6.00-molar solution is

(A) 3.10 grams

(B) 12.0 grams

(C) 29.4 grams

(D) 294 grams

(E) 300. grams

4. A gaseous mixture containing 7.0 moles of nitrogen, 2.5 moles of oxygen, and 0.50 mole of helium exerts a total pressure of 0.90 atmosphere. What is the partial pressure of the nitrogen?

(A) 0.13 atm

(B) 0.27 atm

(C) 0.63 atm

(D) 0.90 atm

(E) 6.3 atm

5. In addition to the information above, which of the following gives the minimum data required to determine the molecular mass of a nonionic substance by the freezing point depression technique?

(A) No further information is necessary.

(B) Mass of solute

(C) Mass of solute and mass of solvent

(D) Mass of solute and volume of solvent

(E) Mass of solute, mass of solvent, and vapor pressure of solvent

6. Which of the following is probably true for a solid solute with a highly endothermic heat of solution when dissolved in water?

(A) The solid has a low lattice energy.

(B) As the solute dissolves, the temperature of the solution increases.

(C) The resulting solution is ideal.

(D) The solid is more soluble at higher temperatures.

(E) the solid has a high energy of hydration.

7. Which of the following does NOT behave as an electrolyte when it is dissolved in water?

(A) CH3OH

(B) K2CO3

(C) NH4Br

(D) HI

(E) Sodium acetate, CH3COONa

8. Which of the following actions would be likely to change the boiling point of a sample of a pure liquid in an open container?

I. Placing it in a smaller container

II. Increasing the number of moles of the liquid in the container

III. Moving the container and liquid to a higher altitude

(A) I only

(B) II only

(C) III only

(D) II and III only

(E) I, II, and III

9. Given that a solution is 5 percent sucrose by mass, what additional information is necessary to calculate the molarity of the solution?

I. The density of water

II. The density of the solution

III. The molar mass of sucrose

(A) I only

(B) II only

(C) III only

(D) I and III

(E) II and III

10. Concentrations of colored substances are commonly measured by means of a spectrophotometer. Which of the following would ensure that correct values are obtained for the measured absorbance?

I. There must be enough sample in the tube to cover the entire light path.

II. The instrument must be periodically reset using a standard.

III. The solution must be saturated.

(A) I only

(B) II only

(C) I and II only

(D) II and III only

(E) I, II, and III

11. Samples of F2 gas and Xe gas are mixed in a container of fixed volume. The initial partial pressure of the F2 gas is 8.0 atmospheres and that of the Xe gas is 1.7 atmospheres. When all of the Xe gas reacted, forming a solid compound, the pressure of the unreacted F2 gas was 4.6 atmospheres. The temperature remained constant. What is the formula of the compound?

(A) XeF

(B) XeF3

(C) XeF4

(D) XeF6

(E) XeF8

12. Based on concepts of polarity and hydrogen bonding, which of the following sequences correctly lists the compounds above in the order of their increasing solubility in water?

(A) Z < Y < X

(B) Y < Z < X

(C) Y < X < Z

(D) X < Z < Y

(E) X < Y < Z

13. Concentrated sulfuric acid is 98% H2SO4 by mass. The density of the solution is 1.8 g/mL. What is the molarity of this solution?

(A) 12 M

(B) 15 M

(C) 17 M

(D) 18 M

(E) None of the above

14. What is the approximate freezing point of a solution prepared by adding 14 g of Na2SO4 to 100.0 g of H2O? (The molal freezing point constant for water is 1.86 0C/m.)

(A) – 0.19 0C

(B) – 0.56 0C

(C) – 1.9 0C

(D) – 3.8 0C

(E) – 5.6 0C

Essays

1. The arthritis drug Celebrex is a selective inhibitor of the enzyme that causes inflammation in humans and consequently has very few, if any, of the side effects associated with traditional nonsteroidal anti-inflammatory drugs, NSAIDs. It has therefore found widespread use in patients suffering from many inflammatory disorders. Celebrex’s molecular formula is C17H14N3SO2F3.

a) Calculate the molecular mass of Celebrex.

b) This anti-inflammatory agent is synthesized from the condensation of 4-sulphonamidophenyl hydrazine, C6H9N3SO2, and the Claisen condensation product of 4-methyl acetophenone and ethyl trifluoroacetate, C11H9O2F3, according to the following reaction:

C6H9N3SO2 + C11H9O2F3 ( C17H14N3SO2F3 + 2H2O

Suppose that a chemist sets up a reaction to prepare Celebrex by combining 20.0 g of each of the above reactants. How much of the anti-inflammatory compound could be synthesized from this reaction? Express your answer in grams and moles.

c) Which reactant is in excess? Which is limiting?

d) By the amount, expressed in grams, is the excess reactant in excess?

e) Suppose the chemist isolates 20.8 g of the purified drug from the reaction. What is the percent yield for this process?

2. A student is instructed to determine the concentration of CoCl2 based upon the absorption of light. The student is provided with a 0.10 M solution of CoCl2 with which to prepare standard solutions with concentrations of 0.020 M, 0.040 M, 0.060 M, and 0.080 M.

a) Describe the procedure for diluting the 0.10 M solution to the concentration of 0.020 M using distilled water, a 100 mL volumetric flask, and a pipet. Include specific amounts where appropriate.

The student takes the 0.10 M solution and determines the percent transmittance and absorbance at various wavelengths. These two graphs represent the data.

b) Identify the optimum wavelength for this analysis.

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I. Difference in temperature between freezing point of solvent and freezing point of solvent and freezing point of solution

II. Molal freezing point depression constant, Kf, for solvent

X = CH3-CH2-CH2-CH2-CH3

Y = CH3-CH2-CH2-CH2-OH

Z = HO-CH2-CH2-CH2-OH

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