Calculate the pOH of a solution at 25⁰C that contains 1 x 10^-10 M of hydronium ions.

• 7

• 4

• 9

• 9

A Weak acid, H_A has a K_a of 1.00 x 10^-5. If 0.100 mole of this percentage of acid dissociated at equilibrium is closest to:

• 99.0%

• 1.00%

• 99.9 %

• 99.9 %

The following equilibrium constants are given:

N₂ + 3H₂  ⇌ 2NH₃; K₁

N₂ +O₂  ⇌ 2NO; K₂

H₂ + 1/2O₂  ⇌ H₂O' K₃

The equilibrium constants for the oxidation of NH₃ by oxygen to give NO is:

• K₂K₃³ /K₁

• KK₂K₃² /K₁

• K₂²K₃ /K₁

• K₂²K₃ /K₁

Identify the correct statement for the change of Gibbs energy for a system (ΔG_system) at constant temperature and pressure

• If ΔG_system > 0, the process is spontaneous

• If ΔG_system =0, the system has attained equilibrium

• If ΔG_system < 0, the system is still moving in a particular direction
  

• If ΔG_system < 0, the system is still moving in a particular direction
  

The enthalpy and entropy change for the reaction:

Br₂ (l) + Cl₂ (g)→ 2BrCl (g)

are 30 kJ mol^-1 and 105 JK^-1 mol^-1 respectively. The temperature at which the reaction will be in equilibrium is:

• 285.7 K 

• 273 K

• 450 K

• 450 K

For the reaction,

CH₄  (g) + 2 O₂ (g) ⇌ CO₂ (g) + 2H₂O (l), 

Δ_rH = - 170. 8 kJ mol^-1

Which of the following statements is not true? 

• At equilibrium, the concentrations of CO₂ (g) and H₂O (l) are not equal

• The equilibrium constant for the reaction is given by K_p = 

• Addition of CH₄ (g) or O₂ (g) at equilibrium will cause a shift to the right

• Addition of CH₄ (g) or O₂ (g) at equilibrium will cause a shift to the right

Which of the following pairs consitutes a buffer?

• HNO₂ and NaNO₂

• NaOH and NaCl

• HNO₃ and NH₄NO₃

• HNO₃ and NH₄NO₃

The hydrogen ion concentration of a 10^-8 M HCL aqueous solution at 298 K (K_w = 10^-14) is:

• 1.0 x 10^-6

• 1.0525 x 10^-7 M

• 9.525 x 10^-8 M

• 9.525 x 10^-8 M

Which of the following, not a correct statement? 

• The electron -deficient molecules can act as Lewis acids

• The canonical structures have no real existence

• Every AB₅ molecules does, in fact, have square pyramid structure

• Every AB₅ molecules does, in fact, have square pyramid structure

820.

HgCl₂ and I₂ both when dissolved in water containing I^– ions the pair of species formed is

• HgI₂ , I₃^-

• Hgl₂, I^-

• HgI₄^3-, I₃^-

• HgI₄^3-, I₃^-