Which of the following processes is endothermic? An atom emits a photon. The ele
ID: 1004653 • Letter: W
Question
Which of the following processes is endothermic? An atom emits a photon. The electron gain process of a fluorine atom. An atom absorbs a photon The condensation of water. None of the above processes are endothermic. Use the delta H degree_f and delta H degree_rxn information provided to calculate delta H degree_f for IF: IF_7s(g) + I_2 (g) rightarrow IF_5(g) + IF(g) delta H degree_rxn = -89 kJ delta H degree_f (kj/mol) IF_7(g) -941 IF_5(g) -840 24 kJ/mol 101 kJ/mo -95 kJ/mo 2-190 kJ/mol -140 kJ/mol Choose the reaction that represents delta H degree_f for Ca(NO_3)_2. Ca^2 +(aq) + 2 NO_3^-(aq) rightarrow Ca(NO_3)2(aq) Ca(s) + 2 N)g) + 6 O(g) rightarrow Ca(NO_3)2(s) Ca(NO_3)2(aq) rightarrow Ca^2+(aq) 2 NO_3 (aq) Ca(s) + N_2 9g) + 3O_2(g) rightarrow Ca(NO_3)2(s) Ca(NO_3)2(s) rightarrow Ca(s) + N_2(g) + N_2(g) + 3O_2(g) What volume of benzene (C_6H_6, d = 0.88 g/mL, molar mass = 78.11 g/mol) is required to produce 1.5 times 10^3 kJ of heat according to the following reaction? 2 C_6H_6(1) + 15 O_2(g) rightarrow 12 CO_2(g) + 6 H_2O(g) delta degree_rxn = -6278 kJ 37mL 21mL 42 mL 19 mL 75 mLExplanation / Answer
1) Answer : C
Since endothermic means the energy supplied to a system. Here Atom absorbed a photon which indicates atom absorbs the light energy.
2) Answer : C
dH rxn = dH products - dH reactants
-89 = -840 + 2*x -(-941 +0)
x = dHf of IF = -95 kJ/mol
3) Answer : D
Ca(s) + N2(g) + 3O2(g) -----> Ca(NO3)2(s)
4) Answer : C
2 C6H6 (l) + 15O2(g) -----> 12CO2(g) + 6H2O(g) dH rxn = -6278 kJ
2 moles of benzene produces 6278 kJ
6278 kJ of heat produced by 2 moles of benzene
1.5 * 10^3 kJ heat -------> 2* 1.5 *10^3/6278 moles of benzene
= 0.4778 moles
mass of C6H6 = 0.4778 * 78.11 = 37.321 g
volume of C6H6 = 37.321/0.88 = 42.41 mL
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