davejake

Optional) Ask your instructor for the name of your unknown liquid. Using van der Waals' equation and the values of a and b for your compound, repeat the calculation for the moles of vapor, Ar (show for Trial 1 below), to determine a more accurate molar mass of the compound. E Calculations (van der Waals equation) Unknown number_-_a = b 1. Moles of vapor, ysps (mol) 2. Mass of vapor, magos (g) Trial I Trial 3 Trial 2 3. Molar mass of compound (g/mol) . Average molar mass (g/mol) "Calculation of from van der Waals' equation for Trial 1. Show work here. boratory Questions cle the questions that have been assigned. Part A.1. The mass of the flask (before the sample in placed into the flask) is measured when the outside of the flask is wet. However, in Part B.3, the outside of the flask is dried before its mass is measured. a. Will the mass of vapor in the flask be reported as too high or too low, or will it be unaffected? Explain. Will the molar mass of vapor in the flask be reported as too high or too low, or will it be unaffected? Explain. art A.1. From the time the mass of the flask is first measured in Part A.1 until the time it is finally measured in Part 3, it is handled a number of times with oily fingers. Does this lack of proper technique result in the molar mass of e vapor in the flask being reported as too high or too low or as unaffected? Explain t A.2. The aluminum foil is pierced several times with large pencil-size holes instead of pin-sizs How will this oversight in the nroced

Given: Delta G = Delta G degree + RT In Q With respect to this equation, which of the following statements is NOT correct? Delta G = 0 is the condition for equilibrium. At equilibrium, Q becomes K. If Q = 1, then Delta G must equal Delta G degree. Delta G degree = 0 is the condition for equilibrium. What is the new pH if 10.0 mL of .10 M HCl is added to 120. ml. of a buffer that is .10 M acetic acid and .10 M acetate, K_2 for acetic acid = 1.8 times 10^-5. 4.71 4.74 4.82 4.67 What is the mass (in g) of silver chromate (MW = 331.7 g/mol) that can dissolve in 1.00 I. of 0.10 M AgNO_3 solution? The solubility product for Ag_2CrO_4: K_sp = 1.2 times 10^-2 7.96 times 10^-9 g 3.98 times 10^-9 g 3.98 times 10^-8 g 1.99 times 10^-8 g What is the total number (n) of e transferred in the following redox equation: 14 H^+ Cr_2O_7^2 + 6 Fe^2+ rightarrow 6Fe^3+ + 2Cr^3+ +7 H_2O n=1 n=3 n=6 n=12 Given 2 Al degree (s) + 3 Cd^2+ (aq) rightarrow 2 Al^3+ (aq) + 3Cd degree (s) For this reaction E degree = 1.26 v. If [Al^3+] = 0.01 M and [Cd^2+] = 10^-4 M. Calculate E from the Nernst equation: E = E_0 - .0257/n In Q 1.34 v 1.26 v 1.18 v 1.21 v

O O 1. KOEt, EtOH 2. O DMSO O

L Moles of vapor·n,..mo) 2. Mass of vapor,m(g) 3. Molar mass of compound (/mol Average molar mass (gfmot) Calculation of from van der Waals' equation for Trial 1. Show work here. a:100(12.) b:10o Laboratory Questions Circle the questions that have been assigned. 1. Part A.1. The mass of the flask (before the sample in placed into the flask) is wet. However, in Part B.3, the outside of the flask is dried before its mass is measured. a. Will the mass of vapor in the flask b. Will the molar mass of vapor in the flask be reported as too high or too low, or will it be unaffected? Explain. flask (before the sample in placed into the flask) is measured when the outside of the flask is be reported as too high or too low, or will it be unaffected? Explain. 2. Part A.1. From the time the mass of the flask is first measured in Part A.1 until the time it is finally measured in Part B.3, it is handled a number of times with oily fingers. Does this lack of proper technique result in the molar mass of the vapor in the flask being reported as too high or too low or as unaffected? Explain. 3. Part A.2. The aluminum foil is pierced several times with large pencil-size holes instead of pin-size. a. How will this oversight in the procedure affect the mass of vapor measured in Part B.3, too low, too high, or unaffected? Explain. b. Will the reported molar mass of the liquid be reported too low, too high, or unaffected? Explain. 4. Part B.2. The flask is completely filled with vapor only when it is removed from the hot water bath in Part B3. 5. Part B.2. Suppose the thermometer is miscalibrated to read 0.3°C higher than actual. Does this error in calibration 6. Part C.1. If the volume of the flask is assumed to be 125ml. instead of the measured volume, would the calculated 7. Part C.2. The pressure reading from the barometer is recorded higher than it actually is. How does this affect the However, when the flask cools, some of the vapor condenses in the flask. As a result of this observation, will the reported molar mass of the liquid be too high, too low, or unaffected? Explain. result in the molar mass of the vapor in the flask being reported as too high, too low, or as unaffected? Explain molar mass of the unknown liquid be too high, too low, or unaffected by this experimental error? Explain. reported molar mass of the liquid: too high, too low, or unaffected? Explairn. 180 Molar Mass of a Volatile Liquid 154

Given: Delta G = delta G degree + RT ln Q With respect to this equation, which of the following statements is NOT correct? Delta G = 0 is the condition for equilibrium. At equilibrium, Q becomes K. If Q = 1, then Delta G must equal delta G degree. delta G degree = 0 is the condition for equilibrium. What is the new pH if 10.0 mL of .10 M HCl is added to 120. mL of a buffer that is .10 M acetic acid and .10 M acetic K_a for acetic acid = 1.8 times 10^-5 4.71 4.74 4.82 4 67 What is the mass (in g) of silver chromate (MW = 331.7 g/mol) that can dissolve in 1.00 L of 0 10 M AgNO_2 solution? The solubility product for Ag_2CrO_4; K_sp = 1.2 times 10^-12 7 96 times 10^-9 g 3.98 times 10^-9 g 3.98 times 10^-8 g 1.99 times 10^-8 g What the total number (n) of e* transferred in the following redox equation: 14H^+ + Cr_2O^2+ + 6 Fe^2+ rightarrow 6 Fe^3+ + 2 Cr^3+ + 7 H_2O n = 1 n = 3 n = 6 n = 12 Given 2 Aldegree(s) + 3Cd^2+(aq) rightarrow 2 Al^3+(aq) + 3Cddegree(s) For this reaction Edegree = 1.26 v. If [Al^3+] = 0.01 M and [Cd^2+] = 10^-4 M. Calculate E from the Nernst equation: E = Eo - .0257/n ln Q 1.34 v 126 v 1.18 v 121 v

Suppose a reactant A undergoes liquid-phase reactions according to the following kinetics scheme: Does a favorable product distribution result from relatively high or relatively low C_A? Explain. Does a favorable product distribution result from relatively high or relatively low T? Explain. Does a favorable (i.e., small) reactor size result from high or low C_A? Explain. Does a favorable reactor size result from high or low T? Explain. Which type of reactor, PFR or single-staged CSTR, should be chosen for this situation, and should it be operated at high, low, or optimal T to achieve favorable product distribution consistent with small size of reactor? Explain. For the kinetics scheme in (a), and regardless of the proper choice of reactor, suppose a CSTR of volume 10 m3 is available to process 0.5 m^3/min of a feed stream with a concentration (C_Ao) of 3000 mol/m^3. If the temperature is such that k_1 = 0.001 (1/sec), and k_2 = 5*10^-5 m^3/mol/sec, calculate the fractional conversion of A and the product distribution (C_A, C_B, C_c) in the exit stream at steady state.

Selma SN1. SN2 O E1 O E2 O electrophilic addition O free radical

a) Suppose a reactant A undergoes liquid-phase reactions according to the following kinetics scheme Reaction Desired?Rate law Activation ener A→B 2 A C A3 i) Does a favorable product distribution result from relatively high or relatively low Ca? Explain. ii) Does a favorable product distribution result from relatively high or relatively low T? Explain. ii) Does a favorable (i.e., small) reactor size result from high or low CA? Explain iv) Does a favorable reactor size result from high or low T? Explain. v) Which type of reactor, PFR or single-staged CSTR, should be chosen for this situation, and should it be operated at high, low, or optimal T to achieve favorable product distribution consistent with small size of reactor? Explain. b) For the kinetics scheme in (a), and regardless of the proper choice of reactor, suppose a CSTR of volume 10 m3 is available to process 0.5 m /min of a feed stream with a concentration (Ca) of 3000 mol/m3. If the temperature is such that k1 = 0.001 (1/sec), and k2= 5*105 m3/mol/sec, calculate the fractional conversion of A and the product distribution (Ca, Cs, C) in the exit stream at steady state