Chemical Equilibrium Concepts

• The conventional equilibrium constant expression (K) for the reaction 2H₂ + O₂ ⇌ 2H₂O is [H₂O]² / ([H₂]²[O₂]).
• For the reaction N₂(g) + 3H₂(g) ⇌ 2NH₃(g), with equilibrium amounts of 0.0420 mole N₂, 0.516 mole H₂, and 0.0357 mole NH₃ in a 3.00-liter container at 400 °C, the equilibrium constant K is 1.99.
• A false statement about dynamic equilibrium is that at equilibrium, forward and backward reactions cease to occur.
• Increasing the temperature of the surroundings shifts the position of equilibrium in favor of endothermic reactions, not exothermic reactions.
• For an endothermic reaction 2CO(g) + 2NO(g) ⇌ N₂(g) + 2CO₂(g) with ΔH = +26 kJ:

Addition of N₂ will shift the reaction

• Addition of N₂ will shift the reaction to the right.

Decrease in temperature will shift the reaction

• A decrease in temperature will shift the reaction to the left.

Addition of catalyst will shift the reaction

• Addition of a catalyst will have no effect on the equilibrium.

Increase in pressure will shift the reaction

• An increase in pressure will have no effect on the equilibrium.
• For the reaction H₂ + I₂ ⇌ 2HI, if the initial amount of H₂ is 'a' moles, I₂ is 'b' moles, H₂ reacted is 'x' moles, the value of K is 4x² / ((a-x)(b-x)).
• If the pH of a solution is 4.80, then the concentration of hydroxide ions, is 1.6 x 10⁻⁹ M.
• The pair that does not show an acid and its conjugate base is H₂SO3 and SO3.
• The percent dissociation of a 0.125 M solution of nitrous acid (HNO₂) with a pH of 2.09 is 6.5%.
• For the reaction H₂ + I₂ ⇌ 2HI, if the partial pressures of H₂, I₂, and HI are 0.0592 atm, 0.1183 atm, and 0.1106 atm, respectively, then K, is 1.74.
• The molecular structure of SF₆ is octahedral.
• The number of lone pairs of electrons in water (H₂O) is 2.
• According to VBT, the shape of CH₄ is sp³.
• The bond angles in a molecule of boron trifluoride are 120°.
• The molecule whose shape is based on lone pairs is H₂O.
• The shape and bond angle of NH₃ are trigonal pyramidal, 107°.
• The relative strengths of acids are determined by the extent to which they ionize in water solution.
• When 0.1 Faraday of electricity is passed through a solution of copper (II) phosphate, the maximum weight of copper deposited on the cathode is 3.2g (Cu=64).
• The quantity of electricity consumed when 10 amperes are consumed in 1 hour during electrolysis is 36 kilo coulombs.
• The concentration in g/dm³ of 4g of NaOH dissolved in 100 ml of H₂O is 40 gdm⁻³.
• The statement that both the momentum and the position of a small particle cannot be known simultaneously with any degree of certainty is attributed to Heisenberg.
• The subsidiary quantum number determines the angular momentum and the shape of the orbital.
• The principal quantum number determines the energy of the orbital occupied by electrons.
• The wavelength of a beam of protons having a velocity of 13.8 x 10⁵ cm/s is 28.8 x 10⁻¹³ m (h = 6.63 x 10⁻³⁴ kgm²/s).
• 3 NH₄ is three moles of ammonia.
• If a given quantity of electricity liberates 2.01g of Hg²⁺, the amount of Zn that would be liberated by the same quantity of current is 0.65g (Zn=65, Hg=201).
• The number of atoms contained in 1 mole of hydrogen molecule is 12.06 x 10²³ atoms.
• The possible l (subsidiary quantum number) when n (principal quantum number) is 3 is 0, 1, 2.
• The wavelength of an electron moving with a velocity of 6.0 x 10⁶ m/s is 1.2 X 10⁻¹⁰ m.
• One inch is equal to 25.40 millimetres.
• The instrument used to find the relative atomic mass of each isotope of an element is called mass spectrometer.
• H₂O is an empirical formula.
• If a compound is 25.9% Nitrogen and 74.1% oxygen, its empirical formula is N₂O₅.
• If the empirical formula of a substance is CH₂O and its molar mass is 180, the molecular formula is C₆H₁₂O₆.
• The amount of CO₂ produced by the combustion of 20 g of CH₄ is 22 g.
• If an atom has a mass of 23 and atomic number 11, then the number of protons is 11.
• Atomic mass unit (amu) is 1/12 th of the mass of carbon atom.
• An element has isotopes with mass number 35 and 37, and the ratio of abundance is 3:1 respectively, the relative atomic mass is 35.5.
• The maximum number of orbitals formed when the principal quantum number n is 3 is 9.
• The number of faradays that pass through a resistance in a circuit carrying a current of 1.68 A for 2 days is 3F.
• The wavelength of a photon with a mass of 1.884x 10⁻³³g travelling at 325 m/s is 1.08 x 10⁻⁸ m.
• For a hydrocarbon containing 40% carbon and 6.7% hydrogen by mass, the empirical formula is CH₃.
• The volume in liters of 40 kg of CCl4 with a density of 1.6 g/cm³ is 25 L.
• The final molar concentration when 25 ml of 1.83 mol/dm³ of NaCl solution is diluted to 100 mL is 0.46 mol/dm³.
• If a solution containing 2 g of Hg(NO₃)₂ was added to Na₂S solution, the mass of HgS produced is 1.57 g.
• If the abundance of isotopes of bromine with relative isotopic masses of 78.919 and 80.917 are 50.52% and 49.48% respectively, then the relative atomic mass of bromine is 79.908.
• The number of sub-orbitals possible when the principal quantum number 'n' is 3 is 9.
• What is the frequency of the yellow-orange light (λ = 589 nm) produced by sodium vapour streetlights? 5.09 x 10¹⁴ Hz.
• Faraday's laws of electrolysis are dependent on the following factors except charge on the ion of the element.
• The statement "The number of moles of different ions discharged by the same quantity of electricity is inversely proportional to their respective charges" is Faraday's second law.
• The rate of a chemical reaction depends on the following except the shape of the reacting molecules.
• One of the incorrect statements about a catalyst/catalytic reaction is catalysts are not generally specific in their actions.
• For the reaction 2A + 3B → 4C + 5D, the rate of the reaction in terms of ΔB would be written as -1/3 ΔB/Δt.
• In the combustion of methane, CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(g), oxygen has the greatest rate of disappearance.
• Molecularity of a reaction is defined as the number of reacting molecules involved in a reaction.
• A major difference that distinguishes the order of a reaction from the molecularity of a reaction is that the order of a reaction is experimentally determined.
• Assuming that each of the graphs has the same concentration and time axes, B has the greatest initial rate of disappearance of reactant.
• If the initial [N₂] was 0.5 M and the [N₂] was 0.45 M after 0.1 s, what is the rate of the reaction? A. 0.500 M/s.
• If the initial concentration of N₂was 0.500 M and the concentration of N₂ was 0.450 M after 0.100 s, what is the rate of NO formation? A. 0.500 M/s.
• If the rate of formation of ammonia is 0.345 M/s, what is the rate of disappearance of N₂? Na (g) + 3 Ha (g) → 2NH3 (g) A. 0.173
• For the reaction 2A + B + C → D + 2E, the rate law is: rate =k[A]²[B][C]⁻¹, which of the following statements is false: the reaction is second order in [C].
• If the concentration of CHCl₃ is increased by a factor of five while the concentration of Cl₂ is kept the same, the rate will increase by a factor of five.
• The first-order reaction A → B, has k = 8.0 s⁻¹.
• The overall order of the rate is first.
• The value of rate constant for experiment 1 is 0.176 per second.