Metal-halide lamps are a type of gas discharge lamp that contain tungsten electrodes doped with a metal M and an additional halide material (usually sodium iodide). The working temperature of the lamp varies between 1000-3000°C. At the working temperature of the lamp, sodium iodide dissociates to produce sodium and iodine atoms in gaseous form. 

NaI(s) → Na(g) + I(g)

The iodine atoms react with the metal M to produce gaseous MI₄. 

M(s) + 4 I(g) ⇌ MI₄(g) 

The equilibrium pressure of I(g) at 1200°C within the lamp is 0.0240 atm. Show quantitatively that the pressure of MI₄ at 1200°C will cause the reaction to go in the reverse direction at 2500°C (the pressure of I(g) is the same). Assume that for the theoretical metal M, the equilibrium constant (K_p) for the reaction is 210 at 1200°C and 15 at 2500°C. 

For the reaction A₃ (g) + B₃ (g) ⇌ 3 AB (g), A and B atoms are represented as green and red colors in the diagram, respectively. Which box represents the system at Q < K_c if K_c = 1?

The reaction of PCl₃ with O₂ gas occurs readily as shown. 

2 PCl₃ (g) + O₂ (g) → 2 POCl₃ (g)

The equilibrium constant K_p for the reaction is 1.02 at 850 K. Will the reaction be at equilibrium when 0.018 atm PCl₃, 0.016 atm O₂, and 0.25 atm POCl₃ are mixed at 850 K? If not, does the mixture need to produce more products or reactants to attain equilibrium?

A sealed vessel initially contains [CO₂] = 0.215 M. Identify if more of the CaCO₃ will form or will some of the existing CaCO₃ decompose as equilibrium is reached in the reaction: CaCO₃(s) ⇌CaO(s) + CO₂(g), K_c = 0.0132.  

Consider the following electrochemical reaction taking place at 45 °C:

Cu_(s) + 2 Ag⁺_(aq) ⇌ Cu²⁺_(aq) + 2 Ag_(s)

The concentrations within the reaction cell are: [Ag⁺] = 1.25 M and [Cu²⁺] = 0.310 M

a. Write an expression for the reaction quotient (Q) for this reaction.

b. What is the value of the reaction quotient (Q)?