Question

these Q make me crazy !!! pls help me

Question 1 (1 point) What is the change in enthalpy (in kJ mol) for the following reaction F,(9) + Cabr,(s) = Cap,(s) + Br,(1) 1) -112 kJmol 2) 504 kJmol 3) -504 kJmol 4) 537 kJmo?" 5) -537 kJmo" Question 2 (1 point) What is true about the following reaction at 25"c? F,(g) + 2HC1 (9) 2017() + H (9) Ahr®-76 kJ mol' Asr--10.13 J mol"K AGrº=79 kJ molt i. The reaction is exothermic. ii. As the reaction proceeds heat is transferred from the surroundings to the system. 1) only 2) si only 3) both i and is 4) neither ner

Answer 1

Question 1 Answer: 5) -537 kJ mol1 Explanation: Balanced net ionic equation: F2 (g) + CaBr2 (s) = CaF2(s) + Brz (1) Reactant Standard molar enthalpy at 298 K Substance AfH° (kJ mol:1) F2 (g) 0 CaBr2 (s) -682.8 CaF2(s) -1219.6 Br2 (1) 0 Product T = 25°C = 298 K AHºrxn = AHºf f products ΔΗ°freactants The reaction is, F2 (g) + CaBr2 (s) = Cafz(s) + Br2 (1) AH°rxn (1 * AHºf CaF2 + 1 AHºfbr2 )– (1 AHºff2+1 * AHºf Cabr2) AH°rxn = [(-1219.6 kJ mol-)+(0 kJ mol:-)-(0 kJ mol:-) - (-682.8 kJ mol:-)] AH°rxn = [(- 1219.6) - (-682.8) ] kJ mol- AH°rxn = -536.5 kJ mol1 The change in enthalpy of the reaction is -537 kJ mol-

Question 2 Answer: 2) ii only What is true about the following reaction at 25 °C? F2 (g) + 2 HCl (g) = 2 CIF (g) + H2 (g) ΔΗ, = 76 kJ mol-1 AS°, = - 10.13 J mol-'K-1 AG°, = 76 kJ mol-1 i. The reaction is exothermic ii. As the reaction proceeds heat is transferred from the surroundings to the system Explanation: • AH = qp, heat absorbed by the system at constant pressure. • AH is negative for exothermic reactions, in which the system evolve heat to the surroundings during the reaction and . AH is positive for endothermic reactions in which the system absorb heat from the surroundings during the reaction. 1. Look at question 2, the change in enthalpy of the reaction (AHºr) is + 76 kJ mol- which is positive. F2 (g) + 2 HCl (g) = 2 CIF (g) + H2 (g) 2. Accordingly, the above reaction is endothermic, which means the system absorb heat from the surroundings during the reaction or heat transferred from the surroundings to the system

CONCLUSION: Statement i is NOT true, because the reaction is endothermic not exothermic. Statement ii is true.