41. When 0.500 g of cyclohexane, C6H12, is combusted in a bomb calorimeter that has a water sheath containing 750.0 g of water, the temperature of the water increased by 5.5 °C. Assuming that the specific heat of water is 4.18 J/(g °C), and that the heat absorption by the calorimeter is negligible, calculate the enthalpy of combustion per mole of cyclohexane.

   (A). 2.90 x 106 J/mol

   (B). 4.20 x 106 J/mol

   (C). 1.19 x 104 J/mol

   (D). 2.97 x 105 J/mol

   (E). 8.21 x 106 J/mol

42. Choose the reaction that illustrates ΔH°f for Ca(NO3)2.

   (A). Ca(s) + N2(g) + 3O2(g)  Ca(NO3)2 (s)

   (B). Ca+(aq) + NO3-(aq)  Ca(NO3)2 (s)

   (C). Ca+(s) + NO3(aq)  Ca(NO3)2 (s)

   (D). Ca(s) + N2(g) + O2(g)  Ca(NO3)2 (s)

   (E). 2Ca(s) + 2N2(g) + 3O2(g)  Ca(NO3)2 (s)

45. Give the equation with the elements in Na2SO4 in their standard state as the reactants and Na2SO4 as the product.

   (A). 2 Na(s) + 1/8 S8 (s, rhombic) + 2 O2(g)  Na2SO4

   (B). Na(s) + S8 (s, rhombic) + 2 O2(g)  Na2SO4

   (C). Na(s) + S (s, rhombic) + ½ O2(g)  NaSO

   (D). Na(s) + 1/8 S8 (s, rhombic) + 2O2(g)  NaSO4

46. A gas cylinder contains 10.0 kg of C3H8 (propane) gas. Calculate the heat associated with the complete combustion of all of the propane in the cylinder. MW of C3H8 is 44.10 g/mol.

C3H8(g) + 5O2(g)  3CO2(g) + 4H2O(g) Δrxn = -2044 kJ

   (A). -5.68 x 105 kJ

   (B). -4.63 x 105 kJ

   (C). +5.68 x 105 kJ

   (D). +4.63 x 105 kJ

   (E). 2.31 x 105 kJ

48. Use the Δof information provided to calculate Δorxn for the following reaction:

SO2Cl2(g) + 2H2O(l)  2HCl(g) + H2SO4(l) Δorxn = ?

Δof (kJ/mol)

SO2Cl2(g) -364

H2O(l) -286

HCl(g) -92

H2SO4(l) -814

49. Calculate the change in internal energy (Δ) for a system that is giving off 26.0 kJ of heat and is changing from 12.00 L to 6.00 L in volume at 1.50 atm pressure. (101.3 J = 1 L∙tm)

50. Use bond energies to calculate the Δrxn for the following reaction:

N2(g) + 3H2(g)  2NH3(g) (balanced?)

51. Which of the following (with specific heat capacity provided) would show the smallest temperature change upon gaining 155 J of heat?

   (A) 25.0 g Au, CAu = 0.128 J/g.°C

   (B) 25.0 g Ag, CAg = 0.235 J/g.°C

   (C) 50.0 g Al, CAl = 0.903 J/g.°C

   (D) 50.0 g Cu, CCu = 0.385 J/g.°C

   (E) 25.0 g granite, Cgranite = 0.790 J/g°C

52. Use the standard reaction enthalpies given below to determine ΔHorxn for the following reaction:

2 NO(g) + O2(g)  2 NO2(g) Δorxn = ?

Given:

N2(g) + O2(g)  2 NO(g) Δorxn = +183 kJ

½ N2(g) + O2(g)  NO2(g) Δorxn = +33 kJ

   (A) -211 kJ

   (B) -117 kJ

   (C) -153 kJ

   (D) +165 kJ

   (E) +795 kJ

What is the [H3O + ] concentration of a solution formed by mixing 50.0 mL of 0.20 M HCl and 50.0 mL of 0.10 M NaOH?

Given 100.0 mL of a buffer that is 0.50 M in HOCl and 0.40 M in NaOCl, what is the pH after 10.0 mL of 1.0 M NaOH has been added? (Ka for HOCl = 3.5  108 ).

What is the pH of a solution prepared by mixing 50 mL of a 0.10 M solution of HF with 25 mL of a 0.20 M solution of NaF? (The pKa of HF is 3.14.)

The chief compound in marble is CaCO3. Marble has been widely used for statues and ornamental work on buildings, including such structures as the Taj Mahal. However, marble is readily attacked by acids via the following reaction.

CaCO₃(s)+H⁺(aq)⇌Ca²⁺(aq)+HCO₃⁻(aq)

Equilibrium constants at 25 ^∘C are listed in the table below.

Substance	Kc	Value of Kc
CaCO3	Ksp	4.5×10−9
H2CO3	Ka1	4.3×10−7
	Ka2	5.6×10−11

What is the molar solubility of marble (i.e., [Ca²⁺] in a saturated solution) in normal rainwater, for which pH=4.20?

In the simulation, select the Table Salt tab, and set the volume and the total number of sodium (Na+) ions as mentioned below. Allow the solution to attain equilibrium. Observe the number of dissolved ions and bound ions from the table displayed on the right. Then, identify which of the following solutions are saturated solutions.

1.0×10−23 L of solution containing 23 Na+ ions.

2.0×10−23 L of solution containing 81 Na+ ions.

3.0×10−23 L of solution containing 115 Na+ ions.

4.0×10−23 L of solution containing 121 Na+ ions.

5.0×10−23 L of solution containing 202 Na+ ions.

6.0×10−23 L of solution containing 213 Na+ ions.

Use the second law of thermodynamics to explain briefly what happens, in terms of the entropy of the stable phase, when the temperature of ice is raised from -10 °C to 10 °C.

Disccuss what happens to copper in photochromic lenses from a redox perspective.

Propose a detailed mechanism for the Knoevenagel condensation, shown below. (6 pts.)

Answer ALL parts. (a) The reaction B + C → D just becomes spontaneous at a temperature of 78.1 °C. When the temperature is increased to 220 °C: (i) Calculate Gibbs free energy (ii) Calculate equilibrium constant (iii) State whether the products or reactants are favoured at this temperature and explain your reasoning (iv) State the assumptions associated with your calculations.

Useful data for this question:

ΔSreaction (B + C → D) = 259.4 J K–1 mol–

Describe one example of a property (and give one equation) of electromagnetic radiation that is particle like.

A flask containing pure NO₂ was heated to 1250K, a temperature at which the Kpvalue for the decomposition of NO2 is 177.

2 NO₂(g) <---------> 2 NO(g) + O₂(g)

Starting with pure NO₂ , the flask is heated and he partial pressure of O2 at equlibrium is 0.133 am. Calculate the partial pressures of NO and NO₂ at equlibrium and the total pressure in the flask at equlibrium.

P_NO ____________________atm

P_NO2____________________atm

P_total____________________atm

14: An electron in hydrogen atom at the energy level n = 7 undergo a transition to level n = 3: Find the frequency and the energy of the emitted photon.

15: An electron jumps from higher energy level to the first energy level with an energy difference of 2.04375 x 10^-18 J. find the initial energy level. Show your calculations,

16: A: What will be the speed of an electron at 4 th energy level? Suppose the electron has a wavelength of 97.3 nm Given Mass of electron is 9.11 x 10^-31 kg. Use de Broglie’s theory.

What is the maximum number of electrons in an atom that can have the following quantum numbers?

(a) n = 4, ms = -1/2

____

(b) n = 5, l = 3

____

(c) n = 6, l = 3, ml = -2

____

(d) n = 2, l = 1, ml = -1, ms = +1/2

____

A)An exactly 500 gram iron ore sample was determined to contain 242 grams of iron. What is the mass percent of iron in the ore?

B) What are the coeffieceints for the following properly balaned reaction-

__Sodium phosphate reacts with___barium nitrate to from ___sodium nitrate and ____barium phosphate

C) What mass of iron is present in a 6.03 gram sample of iron (II) chloride?

Indicate the concentration of each ion present in the solution formed by mixing the following. (Assume that the volumes are additive.)

(a) 30 mL of 0.100 M HCl and 10.0 mL of 0.520 M HCl

H+ _____M

Cl-______ M

(b) 15.0 mL of 0.294 M Na2SO4 and 28.2 mL of 0.200 M KCl

Na+______ M

K+______ M

SO42-______ M

Cl-______ M

(c) 3.50 g of NaCl in 59.3 mL of 0.439 M CaCl2 solution

Na+______ M

Ca2+______ M

Cl-______ M

Limiting Reactions Question #11

Part a.

For the following reaction, 0.289 moles of hydrochloric acid are mixed with 0.562 moles of oxygen gas.

Hydrochloric acid (aq) + oxygen (g) = water (l) + chlorine (g)

What is the FORMULA for the limiting reagent   ________________ and what is the maximum amount of water that can be produces? _____________moles

Part b.

For the following reaction, 9.80 grams of butane (C4H10) are allowed to react with 19.0 grams of oxygen gas.

Butane (C4H10)(g) + oxygen (g) = carbon dioxide (g) + water

What is the maximum amount of carbon dioxide that can be formed? ______________grams

What is the FORMULA for the limiting reagent ______________ and what amount of excess reagent remains after the reaction is complete? _______________grams