6. The equilibrium constant for the reaction 2 HBr (g) → H2(g) + Br2(g) Can be expressed by the empirical formula 11790 K In K-6.375 + 0.6415 In(T K-¹) - T Use this formula to determine A,H as a function of temperature. Calculate A,-H at 25 °C and at 100 °C.

3. Nitrosyl chloride, NOCI, decomposes according to 2 NOCI (g) → 2 NO(g) + Cl2(g) Assuming that we start with no moles of NOCl (g) and no NO(g) or Cl2(g), derive an expression for Kp in terms of the equilibrium value of the extent of reaction, Seq, and the pressure, P. Given that K₂ = 2.00 × 10-4, calculate Seq/ of 29/no when P = 0.080 bar. What is the new value по ƒª/ at equilibrium when P = 0.160 bar? Is this result in accord with Le Châtelier's Principle?

Consider the following chemical equilibrium: 2SO2(g) + O2(g) = 2SO3(g) • Write the equilibrium constant expression for this reaction. Now compare it to the equilibrium constant expression for the related reaction: • . 1 SO2(g) + O2(g) = SO3(g) 2 How do these two equilibrium expressions differ? What important principle about the dependence of equilibrium constants on the stoichiometry of a reaction can you learn from this comparison?

Given Kp for 2 reactions. Find the Kp for the following reaction: BrCl(g)+ 1/2 I2(g) ->IBr(g) + 1/2 Cl2(g)

For a certain gas-phase reaction at constant pressure, the equilibrium constant Kp is observed to double when the temperature increases from 300 K to 400 K. Calculate the enthalpy change of the reaction, Ah, using this information.

Hydrogen bonding in water plays a key role in its physical properties. Assume that the energy required to break a hydrogen bond is approximately 8 kJ/mol. Consider a simplified two-state model where a "formed" hydrogen bond is in the ground state and a "broken" bond is in the excited state. Using this model: • Calculate the fraction of broken hydrogen bonds at T = 300 K, and also at T = 273 K and T = 373 K. • At what temperature would approximately 50% of the hydrogen bonds be broken? • What does your result imply about the accuracy or limitations of the two-state model in describing hydrogen bonding in water? Finally, applying your understanding: • Would you expect it to be easier or harder to vaporize water at higher temperatures? Why? If you were to hang wet laundry outside, would it dry more quickly on a warm summer day or on a cold winter day, assuming humidity is constant?

(3 pts) Use the Kapustinskii equation to calculate the lattice enthalpy for MgBr2 anddiscuss any differences between this result and that from #4.

(3 pts) Silver metal adopts a fcc unit cell structure and has an atomic radius of 144 pm. Fromthis information, calculate the density of silver. Show all work.

4. (3 pts) From the information below, determine the lattice enthalpy for MgBr2. Show all work. AH/(kJ mol-¹) Sublimation of Mg(s) +148 lonization of Mg(g) +2187 to Mg2+(g) Vaporization of Br₂(1) +31 Dissociation of Br,(g) +193 Electron gain by Br(g) -331 Formation of MgBr₂(s) -524