OAU Chemistry 2013/2014 Past Questions

During the electrolysis of dilute tetraoxsulphate(VI) acid solution, 0.05 mole of electrons were passed. What volume of gas was produced at the anode?

Platinum electrodes are dipped into copper sulphate solution in a voltameter. The solution left after electrolysis is,

What volume of water is produced when a mixture of 150cm^3 of hydrogen and 100cm³ of oxygen is exploded in a eudiometer?

Given the half-cell reaction, 2Br ⟶ Br2, how many moles of electron will be required to produce 0.56dm3 of bromine at s.t.p.? [molar volume of gas at s.t.p. = 22.4dm3]

The equilibrium constant, Kc for the reaction. NO_(g) + 1/2O_2(g) ⟶ NO_2(g), is 35.2. What is the value of Kc for the reaction NO_2(g) ⟶ NO_(g) + 1/2O_2(g)?

An atom has a core and outside the core an electron occupies an orbital for which the principal quantum number, n = 4, l= 0, m = 0, and s = +1/2 or -1/2. The atom is likely to be

An element B, has two isotopes ²⁰₁₀B and ²²₁₀B present in ratio 2:3. The relative atomic mass of B is,

A chloroform solution of pure organic compound was spotted at a distance 0.80cm from the base of a 20cm long chromatoplate. If the compound has the rf-value of 0.505 and moves half way up the 20cm long plate, what is the distance of the solvent front from the top of the plate upon elution?

The main organic product formed when bromine water is added to but - 1 - ene is

Valence shell electron pair theory through hybridization predicts that boron trichloride is

What volume of 0.750moldm^-3 Na₃CO₃ solution could be diluted to 250cm³ to reduce the concentration to 0.025moldm^-3?

When 70cm³ of 3.0moldm^-3 Na₂CO₃ is added to 30cm^3 of 1.0moldm^-3 NaHCO3, the concentration of Na+ ions in moldm^-3 in the solution is,

The reaction, Y ⟶ product is of first order with the initial concentration of Y= 3.55 x 10³ moldm^-3 and the rate constant of 5.25 x 10^-1s^-1. What is the half-life of the reaction?

What quantity of current is required to deposit 2.4g of copper in a period of 750 seconds during an electrolytic deposition process? [Cu = 64, 1F = 96500 coulomb]

The standard reduction potentials for the following half-cell reactions are: 2H₂O_(l) = O_2(g) + 4H⁺_(aq) + 4e $E^0 = -1.23V;$ 2H₂O₂(l) = 2O₂(g) + 4H+(aq) + 4e; [insert equation]E⁰ = -0.68V What is the E° for the reaction, 2H₂O_(l) = 2H₂0_(l) + O_2(g) at 298K?

Bonding in ammonium chloride is

A chemical equilibrium is established when

The basic tenet of valence bond electron pair repulsion theory is that the pairs of electrons making the sigma bonds dictate the shape of molecules. The pi — bonds often encounter in some molecules serve to,

Excess ethanol was sparked with 3g of pure oxygen in a combustion chamber. How many molecules of CO2 are produced? [N = 6.02 x 10²³ molecules mol^-1]

Oxygen is extracted from water by

Forty (40) grams of sodium nitrate were added to 50cm³ of water to give a saturated solution at 289K. If the solubility of the salt is 10.50 moldm^3 at the same temperature, what percentage of the salt is left undissolved'? [Na = 23, N = 14 and 0 = 16]

The energy for the dissociation of molecule AB in kJ in the diagram of energy against the reaction coordinate shown below is,