Consider the equilibrium between liquid water and gaseous water: H_2 O (1) H_2 O
ID: 1050139 • Letter: C
Question
Consider the equilibrium between liquid water and gaseous water: H_2 O (1) H_2 O (g) Predict the signs of delta H degree and delta S degree for the evaporation of water and then determine whether the process of evaporation is entropically or enthalpically driven. Enthalpically because it is exothermic and moves toward less disorder. Enthalpically because it is exothermic and moves toward more disorder. Entropically because it is endothermic and moves toward less disorder. Entropically because it is endothermic and moves toward more disorder. The vapor pressure of a liquid is defined to be the pressure of a gas that is in thermodynamic equilibrium with its liquid phase in a closed container at a fixed temperature. What is the vapor pressure for liquid water at 75 degree C? 0.063 atm 0.41 atm 2.45 atm 15.8 atm Use the chemical reactions shown below to find the delta H degree for the formation of solid magnesium oxide, MgO(s). 2H_2(g) + O_2) rightarrow 2H)_2O(1) delta H degree = -572 kj Mg(s) + 2HCI(aq) + H_2(g) delta H degree = -467 kj MgO(s) + 2HCI(aq) rightarrow MgCl_2(aq) + H_2)(1) delta H degree = -151 kj -1190 kj/mol -904 kj/mol -602 kj/mol -332 kj/mol -30 kj/mol A 5.0 g sample of aluminum pellets (specific heat capacity of 0.89 J/g-deg) and a 10.0 g sample of iron pellets (specific heat capacity of 0.45 J/g-deg) are heated to 100 degree C. The mixture of hot iron and aluminum is then dropped in to a breaker containing 97.3 g water (specific heat capacity of 4.18 J/g-deg) at 22.0 degree C. Predict the final temperature of the metal and water mixture, assuming that there is no heat lost to the surroundings. 20 degree C 25 degree C 78 degree C 122 degree CExplanation / Answer
21) For the isothermal expansion of a ideal gas in vacuum, no work is done by the system, the internal energy remains zero, thus true statement would be,
b. II only
22) For the reaction 1, being an exothermic reaction,
A. dSsys > 0, dSsurr <0, dSuniv > 0
23) For reaction 2, the signs are,
C. dHo < 0, dSo < 0, dGo < 0
24) For the decomposition of HF to H2 and F2, the true statement would be,
B. Under these conditions the reaction would be spontaneous in the reverse direction.