Exam 1
Determine the boiling point in Celsius of a liquid at an external pressure of 373 torr if its normal boiling point is 84.2 degrees celsius and its enthalpy of vaporization is 49.5 kJ/mol. 1 atm = 760 torr
69.5 degrees celsius
A reaction vessel initially contains 8.15 atm H2, 8.15 atm Br2, and 0.283 HBr. At the temperature of the reaction, Kp = 5.28. Calculate the equilibrium pressure in atm of HBr.
H2 (g) + Br2 (g) <--> 2 HBr (g)
8.87
Calculate the pOH of a 1.658 M NaOH solution
-0.220
Calculate the mass in grams of copper that can be electroplated
using a current of 15.0 A for 24.0 hours. HINT: F = 96,485 C / mol e–;
1 A = 1 C/s
Cu2+(aq) + 2 e– → Cu(s)
427 g Cu
ΔHrxn˚ for a reaction is –25.8 kJ/mol. The equilibrium constant for
the reaction is 1.4 x 103 at 25 ˚C. What is the equilibrium constant for the
reaction at 382 ˚C?
5.0
A solution is 44.3% benzene (molar mass = 78.108 g/mol). Calculate the mole fraction of benzene
0.610
Calculate the melting point in celsius of a solution that is 2.79% benzene (molar mass = 78.108g/mol) by mass in carbon tetrachloride. The normal melting point of CCl4 is -22.9 degrees celsius and Kf = 29.9 C/m.
-33.9
Calculate the pH of a 2.96e-3 M H2SO4 solution. Ka2 for H2SO4 is 0.012.
2.30
Calculate the entropy of vaporization for methanol if the normal
boiling point of methanol is 64.7 ˚C and its enthalpy of vaporization is
35.28 kJ/mol.
104.5 J/molK
34.2 g of an organic nonelectrolyte compound are dissolved in enough dimethyl ether (CH3OCH3) to make 1.67 L of solution at 35.1 degrees celsius. If the osmotic pressure of the solution is 890 torr, calculate the molar mass of the dissolved organic compound in g/mol.
442
An aqueous solution is 25.01% NaNO3 by mass. Calculate the molarity of the solution. The density of the solution is 1.184 g/mL.
3.484
Calculate the half-life in hours of a nuclide that loses 24.7% of its mass in 61.2 hours.
149
28 mL of a weak base (Kb = 9.94e-9) with a concentration of 0.24 M are being titrated with aqueous 0.11 M HBr. Calculate the pH at the equivalence point.
3.56
A reaction has a change in enthalpy of the reaction (Hrxn) of 96 kJ and a change in entropy of the reaction (Srxn) of 246 J/K. Calculate the change in entropy for the universe (Suniverse) at 25 degrees celsius. Will this reaction be spontaneous?
-76.2 J/K
Not spontaneous
For a certain metal, M, the solubility product constant of M(OH)3 is 5.54e-22. Calculate the pH when M(OH)3 will begin to precipitate in a 2.152 M MBR3 solution.
6.80
If 97.1 mL of 0.214 M Na3PO4 is added to 67.9 mL of 0.689 M Na2SO4, find the molarity of sodium ions in the final solution.
0.945
A solution contains a mixture of benzene and another volatile organic liquid. The vapor pressure of benzene at the temperature of the solution is 89.4 torr. The vapor pressure of the other organic compound is 488 torr. If the vapor pressure of the solution is 144.4 torr, find the mole fraction of benzene for the solution, assuming ideal behavior.
0.862
23.6 mL of a weak base (Kb = 4.32e-10) with a concentration of 0.298 M are being titrated with aqueous 0.121 M HCl. Calculate the pH after 16.7 mL of HCl solution has been added.
5.03
Calculate ΔGrxn˚ for CaCO3(s) → CaO(s) + CO2(g)
Given:
Ca(s) + CO2(g) + ½ O2(g) → CaCO3(s) ΔGrxn˚ = –734.4 kJ
2 Ca(s) + O2(g) → 2 CaO(s) ΔGrxn˚ = –1206.6 kJ
131.1 kJ
Calculate K at 25.0 ˚C for the reaction below.
N2O(g) + NO2(g) 3 NO(g) ΔHrxn˚ = 159.1 kJ
ΔSrxn˚ = 172.3 J/K
1.5e-19
Calculate the change in thermal energy in kJ for a 206 g sample of acetone (molar mass = 58.08g/mol) to change from -125 degrees celsius to 32.4 degrees celsius.
Enthalpy of fusion is 5.73 kJ/mol
Enthalpy of vaporization is 31.3 kJ/mol
Melting point is -94.7 degrees celsius
Boiling point is 56.1 degrees celsius
Specific heat capacity for solid, liquid, and gas is 1.65 J/(gC), 2.16 J/(gC), and 1.29 J/(gC)
87.2
A reaction vessel initially contains 0.127 atm H2, 0.585 atm Br2, and 9.93 atm HBr. At the temperature of the reaction, Kp = 7.53. Calculate the equilibrium pressuree in atm of H2.
H2 (g) + Br2 (g) <--> 2HBr (g)
2.02
Calculate the pH of n aqueous NH4NO3 solution with a concentration of 1.799 M NH4NO3. Kb for NH3 = 1.76e-5.
4.50
Determine which species undergo reduction and oxidation. Write
the balanced redox reaction and the line notation for the galvanic cell.
Then calculate the standard cell potential.
Ag+(aq) + e– → Ag(s) E˚ = 0.80 V
Au3+(aq) + 3 e– → Au(s) E˚ = 1.50 V
0.70 V
A reaction vessel initially contains 3.77 atm H2, 6.32 atm Br2, and 0.104 atm HBr. At the temperature of the reaction, Kp = 0.744. Calculate the equilibrium pressure in atm of HBr.
H2 (g) + Br2 (g) <--> 2HBr (g)
2.93