Question

For the reaction 4NH3(g)+502(g 4NO() +6H20(g) ΔΗ'--905.2 kJ and ΔS°-180.5 JK The maximum amount of work that could be done when 1.74 moles of NH (g) react at 316 K, 1 atm is kJ and ΔSo are independent of temperature. Assume that Consider the reactiodn The standard free energy chanpe for this reaction is 461.9 kJ The free energy change whea 2.00 moles of BrF() react at standard condition k3 What u the masimium omouet of wetual work: thit the rotion of 20 moe of Brtsto is caable of producing n aroudings under atand condnionat t' ne wok cn be do, er ne of 2.00 enter none Which of the following transformations represent an increase in the entropy of the systenm Choose all that apply 2 30 g CiHgOH (liquid, 344K) 30gCHOH (liquid, 167K3) ■ 5 mol N2 (1.39 atm, і99K)-→5 mol N2 (1.39 atm, 398K) 2 3 mol H2 (5.42 L, 226)3 mol H2 (10.8 L, 226K) 25 g Cr (solid, 2.130 10'K) 25 g Cr (liquid, 2.130x10K) 30 g C2H5OH (gas, 352K)一→30 g C2H5OH (liquid, 352K)

Answer 1

Gibbs free energy is equal to maximum work that can be obtained .

Hence, Maximum work done when 4 mole NH₃ (g) reacts

$\Delta G$^o = $\Delta H$^o - T$\Delta S$^o

= -905.2 *10³ - 316*180.5

= -905200 - 57038

= - 962238 J

Or, $\Delta G$^o = w_max = - 962.23 KJ.

Now, when 1.74 moles NH₃(g) reacts (962.23*1.74/4)

= - 418.57 KJ.

Part 2

Free energy change of the reaction = 461.9 KJ.

In the reaction 2 mole BrF₃(g) reacts.

Therefore, free energy when 2 mole BrF₃ reacts at standard condition = 461.9 KJ.

Maximum work done (W_max) = standard free energy change = 461.9 KJ.

Part 3.

Entropy is a measure of randomness.

Entropy increases when temperature is raised, when solid is converted to liquid and when volume has increased .

Therefore the transformations where entropy increases are

5 mol N₂ (1.39 atm, 199 K ) $\to$ 5 mol N₂ ( 1.39 atm, 398 K)

3 mol H₂ ( 5.42 L, 226 K) $\to$ 3 mol H₂ ( 10.8 L, 226 K)

25 g Cr (solid, 2.139*10³ K) $\to$ 25 g Cr ( liquid, 2.130*10³ K)