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2. Based on the data of standard enthalpy of formation and standard wu that thes

ID: 694867 • Letter: 2

Question

2. Based on the data of standard enthalpy of formation and standard wu that these thermodynamic quantities are independent of temperalE Substance BCl (8) mlar entropy of compounds t tm and25C in this question 402.96 0. 0 92.31 290.17 5.9 130,7 862 HCI ( Answer the following questions for the reaction: 2 B (s) "we 6 HCI (g) 2 BCI, (g) + w(g) t the standard state and 25 and 10 C AHun at the starndard state and 25 C (b) (2pt) Determine the entropy change of the above reaction ASon a (c) (Spt) Determine Gibb free energy of reaction AGs at the stando

Explanation / Answer

Given reaction is-

2B + 6 HCl = 2BCl3 + 3H2

(a) Enthalpy change = enthalpy of product - enthaalpy of reactant

= [2 * (-402.96) + 3 * 0] - [ (2 * 0) + 6 * (-92.31)]

= -252.06 kJ mol-1

(b) entropy change = entropy of product - entropy of reactant

= [2 * (290.17) + 3 *(130.7)] - [ (2 * 5.9) + 6 * (186.2)]

= (580.34 + 392.1) - (11.8 + 1117.2)

= 972.44 - 1129

= - 156.56 J K-1 mol-1

(c) gibbs free energy of reaction = enthalpy change - temperature x entropy change

from above two solution,

= -252.06 kJ mol-1 - [ 283 K * ( - 156.56 J K-1 mol-1) ]

= -252.06 kJ mol-1 + 44.3 kJ mol-1

= - 207.76 kJ mol-1