Question 2 (c)

(c) The tank is cooled to 250C, which is well below the boiling
 point of methanol. It is found that small amounts of H2(g) and CO(g)
 have dissolved in the liquid CH30H. Which of the two gases would you
 expect to be more soluble in methanol at 250C? Justify your answer.
 The only attractive forces between molecules of H2 and CH30H would be
 due to weak London dispersion forces (LDFs). In contrast, the LDFs are
 stronger between CO molecules and CH30H molecules because CO has more
 electrons than H . In addition CO is slightly polar; thus
 intermolecular dipole-dipole attractions can form between CO molecules
 and CH30H molecules. With stronger intermolecular interactions between
 molecules of CO and CH30H, CO would be expected to be more soluble in
 CH30H than 1--12. 1 point is earned for the correct answer and

Question 3 (b)

In many organisms, glucose is oxidized to carbon dioxide and water,
 as represented by the following equation. C6H1206(s) + 6 02(g) 6
 C02(g) + 6 H20(1) A 2.50 g sample of glucose and an excess of 02(g)
 were placed in a calorimeter. After the reaction was initiated and
 proceeded to completion, the total heat released by the reaction was
 calculated to be 39.0 kJ. (b) Calculate the value of AHO, in kJ mol-I,
 for the combustion of glucose. Im01CH O 6 12 6 2.50 g x 180.16 g
 C6H1206 Cb90kJ = 0.0139 mol C6H1206 1 point is earned for the correct
 answer. -(3,810 k.J mol-I 0.0139 mol

Question 5 (b)

(b) Describe the steps in a procedure to prepare 100.0 mL of 1.250 M
 NaOH solution using 5.000 M NaOH and equipment selected from the list
 below. Balance 50 mL buret Eyedropper 25 mL Erlenmeyer flask 100 mL
 Florence flask Drying oven 100 mL graduated cylinder 25 mL pipet Wash
 bottle of distilled H20 100 mL volumetric flask 100 mL beaker Crucible
 Pipet 25.00 mL of 5.000 M NaOH solution into the 100 mL volumetric
 flask. Fill the volumetric flask to the calibration line with
 distilled water, using an eyedropper for the last few drops is
 advised. Cap the volumetric flask and invert several times to ensure
 homogeneity. 1 point is earned for descriptions of any two of the
 three steps. An additional point is earned if all three steps are

  • Eyedropper


Question 6 (a)

(ii) Estimate the numerical value of the bond angle in an ethyl
 methanoate molecule. Explain the basis of your estimate. The Cx is the
 central atom in a tetrahedral arrangment of bonding electron pairs;
 thus the angle would be approximately 109.50 1 point is earned for the
 correct angle with an appropriate explanation.

structural formula molecular shape 10 ball-and-stick model

In a tetrahedral molecular geometry, a central atom is located at
 the center with four substituents that are located at the comers of a
 tetrahedron. The bond angles are cos-l(-%) = 109.4712206...0 = 109.50
 when all four substituents are the same, as in methane (CH4) as well
 as its heavier analogues. Tetrahedral molecular geometry - Wikipedia

Question 6 (c)

(ii) Explain, in terms of processes occurring at the molecular
 level, why the pressure in the flask remained constant after 60.
 seconds. At the equilibrium vapor pressure, the rate of molecules
 passing from the liquid to the gas phase (vaporizing) equals the rate
 of gas phase molecules passing into the liquid phase (condensing). 1
 point is earned for the correct explanation.

Phase changes Of matter solid @ 20" Encyclopædia Britannica, Inc gas
 melting freezng liquid

(iv) After 80. seconds, additional liquid ethyl methanoate is added
 to the container at 200C. Does the partial pressure of the ethyl
 methanoate vapor in the container increase, decrease, or stay the
 same? Explain. (Assume that the volume of the additional liquid ethyl
 methanoate in the container is negligible compared to the total volume
 of the container.) The artial ressure of the va or sta s the same
 because the equilibrium vapor pressure for 200C has already been
 reached. Because the temperature remains constant, the vapor pressure
 would remain unchanged. 1 point is earned for the correct answer with
 an explanation.

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