Physical Chemistry & Transition Elements Random Retrieval

Consider a cell constructed from the following half-cells:

Zn²⁺_(aq) + 2e^- <=> Zn_(s) E^ϴ/V = -0.76

Cu²⁺_(aq) + 2e^- <=>Cu_(s) E^ϴ/V = +0.34

Which half-cell will form the cathode in this cell? Think very carefully about the definition of a cathode!

For this question, look at the resource, ‘A Selection of Standard Electrode Potentials’ (For this quiz, you will need to open or download the Data Sheet, ‘A Selection of Standard Electrode Potentials’. This can be found in TOOLS>Data Sheets)

Which chemical species is the most powerful reducing agent?

Which of these complex ions have a colour in solution?

(i) [Sc(H₂O)₃]²⁺

(ii) [CuCl₂]^-

(iii) [Zn(OH)₄]^2-

(iv) [Co(H₂O)₆]²⁺

Which first-row d-block metal forms hydrated ions in the +3 state which undergo a ligand exchange reaction to form a deep red complex ion with thiocyanate ions, SCN^-.

Which metal forms aqueous ions in the +2 state which precipitate as a hydroxide on adding ammonia solution and redissolve to form a deep blue solution

Look at the chemical equation below.

CH_4(g) + H₂O_(g)=> CO_(g)+ 3H_2(g)

Using your answers to Questions 6 and 7, calculate the Gibbs Energy change ΔG, for the process if it is carried out in a reactor vessel at 1500^oC.

If this question is from a Random Retrieval, you can also carry out this calculation by first working out values for ΔS^Ɵ and ΔH^Ɵ by selecting the appropriate data from the ‘Selection of Thermodynamic Data’ in TOOLS.

For which of these species is the value of the electron affinity positive?

(i) F

(ii) Cl

(iii) O

(iv) O^-

The standard enthalpy change when one mole of an ionic compound forms from free gaseous ions is called the:

Consider the following equilibrium for the Haber-Bosch process:

3H_2(g) + N_2(g) <=>2NH_3(g)

32.0 mol of H₂ was combined with 12.0 mol of N₂ and the mixture sealed and pressurised in a vessel of volume 2.00 dm³. The mixture was left until no further observable change in composition took place. At this point, 4.00 mol of NH₃ was found to be present in the mixture. The pressure was recorded as 200 000 kPa.

Calculate the value of K_c (in units: mol^-2 dm⁶) under these conditions.

Consider the values of the equilibrium constant for this reversible reaction:

H_2(g) +I_2(g) <=> 2HI_(g)

Temperature: 500K, value of K_c = 160

Temperature: 1000K, value of K_c = 54.

This information shows that:

(i) HI decomposes rapidly at 500 K

(ii) Raising the temperature causes the equilibrium to shift to the left

(iii) Raising the pressure causes the equilibrium to shift to the right

(iv) The reaction is exothermic