Requirements: 1. Use given values as stated in questions below. 2. Clearly State

Question

Requirements:

1. Use given values as stated in questions below.

2. Clearly State Answer

3. (Please) LEAVE A COMMENT if you are currently working on the problems.

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4. Calculate the mass of methane that must be burned to provide enough heat to convert 330.0 g of water at 37.0Ý°C into steam at 124.0Ý°C. (Assume that the H2O produced in the combustion reaction is steam rather than liquid water.)

8. Identify the following statements as true or false. (Use the drop-down menu and select "True" or "False" for each. You must get all 6 correct.)

A. All systems become more disordered spontaneously.

B. Both ?Ssys and ?Ssurr must equal zero at equilibrium.

C. The entropy of the universe is constant; the energy of the universe decreases towards a minimum.

D. All spontaneous processes release heat.

E. If a reaction is spontaneous, the reverse reaction is non-spontaneous.

F. If a process decreases the randomness of the particles of a system, the entropy of the system increases.

11. Urea ((NH2)2CO) can be formed from ammonia and carbon dioxide as shown in the following reaction. The ?HÝ° value for this synthesis is -134.0 kJ. Calculate the ?HÝ°f for urea.

2NH3(g) + CO2(g) ? (NH2)2CO(s) + H2O(l)

12. The ?SÝ° value for urea the synthesis reaction above is -424.0 J/K. Calculate SÝ° for urea.

Tries 0/99

13. Calculate ?GÝ° for the synthesis of urea under standard conditions (298 K and 1 atm).

Tries 0/99

14. Compute the standard free energy change for the following reaction.

O3(g) + NO(g) ? NO2(g) + O2(g)

15. The most important commercial process for generating hydrogen gas is the water-gas shift reaction:

CH4(g) + H2O(g) ? CO(g) + 3H2(g)

Use tabulated thermodynamic data to find ?GÝ° for this reaction at the standard temperature of 25Ý°C.

16. Now calculate ?GÝ°1100 for this process when it occurs at 1100 K.

17. The molar enthalpy of fusion (?HÝ°) of fluorine is 0.260 kJ/mol, and the molar entropy of fusion (?SÝ°) of fluorine is 4.851 J/mol K. Using this information, estimate the freezing point of fluorine. (You must answer in Kelvin.)

Explanation / Answer

4)

Enthalpy of combustion of Methane is = -890.4 kJ/mol

Heat required to convert water into steam = 330*2260 J

Heat required to raise temperature of water from 37 to 100 = 330*4.2*(100-37) J

Heat required to raise temperature of steam = 330*(124-100)*1.996 J

Heat balance (assuming mass of methane required is x)

( x/16)*890.4*1000 = 330*2260 +330*4.2*(100-37) +330*(124-100)*1.996

x= 3.394 grams

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8)

A)False--- In chemical thermodynamics, an endergonic reaction (also called an unfavorable reaction or a nonspontaneous reaction) is a chemical reaction in which the standard change in free energy is positive, and energy is absorbed. The total amount of energy is a loss (it takes more energy to start the reaction than what you get out of it) so the total energy is a negative net result.

B) True ---In a thermodynamic system, a "universe" consisting of "surroundings" and "systems" and made up of quantities of matter, its pressure differences, density differences, and temperature differences all tend to equalize over time - simply because equilibrium state has higher probability than any other

C) False--- the second law of thermodynamics, states that the total entropy of any system cannot decrease. The entropy of the whole universe, assumed to be an isolated system, cannot decrease. In fact the entropy of the universe is always increasing

D)False

E)True

F) True--- The definition of entropy is the measure of disorder in a system. By decreasing randomness you have decreased disorder and therefore have decreased energy in system but the energy was transferred to surroundings

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11)

The given balenced chemical reaction is

2 NH3(g) + CO2(g) ? (NH2)2CO(s) + H2O(l)

a) ?H0 for synthyis reaction = 134.0 kJ

But ?H0 = ?n*?H0 f products - ?m*?H0 f reactants

( where n,m are the moles of products and reactants)

-134.0kJ = [?H0 f (NH2)2CO(s) + ?H0 f H2O(l)] - [2*?H0 f NH3(g) + ?H0 f CO2(g) ]

- 134.0kJ = [?H0 f (NH2)2CO(s) + (-285.8kJ)] - [2*(-45.9kJ) + (-393.5kJ]

-134.0kJ = [?H0 f (NH2)2CO(s) -285.8kJ] - [-91.8kJ -393.5kJ]

-134.0 kJ = [?H0 f (NH2)2CO(s) -285.8kJ] - [-485.3kJ]

-134.0 kJ = [?H0 f (NH2)2CO(s) +199.5kJ]

?H0 f (NH2)2CO(s) = -134.0 kJ -199.5kJ

= -333.5 kJ

Therefore ?H0 f (NH2)2CO(s) = -333.5 kJ

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12)

?S0 for synthyis reaction = -424.0 J /K

But ?S0 = ?n*S0 products - ?m*S0 reactants

( where n,m are the moles of products and reactants)

-424.0J/K = [?S0 (NH2)2CO(s) + ?S0 H2O(l)] - [2*?S0 NH3(g) + ?S0 CO2(g) ]

-424.0J/K = [?S0 (NH2)2CO(s) + (70J/K)] - [2*(192.8J/K) + (213.8J/K]

-424.0J/K= [?S0 (NH2)2CO(s) +70J/K] - [385.6J/K +213.8J/K]

-424.0J/K= [?S0 (NH2)2CO(s) +70J/K] - [599.4J/K]

-424.0J/K= [?S0 (NH2)2CO(s) -529.4J/K]

?S0 (NH2)2CO(s) = -424.0 J/K +529.4J/K

= 105.4 J/K

Therefore ?S0 (NH2)2CO(s) = 105.4 J/K

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13) Let we calculate the ?G0 for the synthysis of urea at standard condition 298 K and 1.0atm.

we know that ?G0 = ?H0 - T *?S0

Substituting the all values in the above equation then we will get ?G0 .

Therefore

?G0 = (-134.0 kJ)- 298 K *(-424.0 J/K)

= (-134.0 kJ) - 298 K*(-424.0 *10-3kJ/K)

= -134.0kJ - 126.352 kJ

= -260.352 kJ

Therefore ?G0 = -260.352 kJ

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