Re-take Quiz (Mid-Term Syllabus Content)

Fill in the blanks appropriately to answer the given question correctly:

Question: The solubility of the Group II sulfates decreases down the group. Explain this trend.

Answer: ΔH_latt and ΔH_hyd both 1 , ΔH_latt 2 by a 3 extent and ΔH_hyd 2 by a 4 , ultimately ΔH_sol becomes 5 exothermic or 5 negative.

• 1 = decrease

  2 = decrease

  3 = small

  4 = large

  5 = less

• 1 = decrease

  2 = decrease

  3 = large

  4 = small

  5 = less

• 1 = increase

  2 = increase

  3 = small

  4 = large

  5 = more

• 1 = increase

  2 = increase

  3 = large

  4 = small

  5 = more

Answer explanation

Answer Explanation

Calculate the solubility of BaSO₄ in g per 100 cm³ of solution.

M_r of BaSO₄ is 233.4

• 2.34 x 10^-4 g per 100 cm³ of solution

• 2.34 x 10^-5 g per 100 cm³ of solution

• 2.34 x 10^-3 g per 100 cm³ of solution

• 1.08 x 10^-3 g per 100 cm³ of solution

Answer explanation

Answer Explanation

Calculate standard enthalpy change of formation in kJ/mol.

• ΔH^Θ_f of SO₄^2-= -652 kJ.mol^-1

• ΔH^Θ_f of SO₄^2-= -552 kJ.mol^-1

• ΔH^Θ_f of SO₄^2-= -752 kJ.mol^-1

• ΔH^Θ_f of SO₄^2-= -852 kJ.mol^-1

Answer explanation

Answer Explanation

The lattice energy of BaSO₄(s) is greater than/more negative than the lattice energy of Cs₂SO₄(s). Choose the correct explanation for it.

• 1. 1. Ba²⁺ ion is smaller than Cs⁺

  2. 2. Ba²⁺ ion has a larger charge than Cs⁺

  3. 3. Stronger force of attraction between the SO₄^2- ions for Ba²⁺ than Cs⁺

• 1. 1. Ba²⁺ ion is larger than Cs⁺

  2. 2. Ba²⁺ ion has a larger charge than Cs⁺

  3. 3. Stronger force of attraction between the SO₄^2- ions for Ba²⁺ than Cs⁺

• 1. 1. Ba²⁺ ion is smaller than Cs⁺

  2. 2. Ba²⁺ ion has a smaller charge density than Cs⁺

  3. 3. Stronger force of attraction between the SO₄^2- ions for Ba²⁺ than Cs⁺

• 1. 1. Ba²⁺ ion is smaller than Cs⁺

  2. 2. Ba²⁺ ion has a larger charge than Cs⁺

  3. 3. Less strong force of attraction between the SO₄^2- ions for Ba²⁺ than Cs⁺

Answer explanation

Answer Explanation

Calculate the minimum temperature at the which this becomes feasible.

• T = -58.7 ^ₒ C

• T = 58.7 ^ₒ C

• T = -38.7 ^ₒ C

• T = 38.7 ^ₒ C

Answer explanation

Answer Explanation

Calculate the standard Gibbs free energy change for this reaction

at 25 ^ο C.

ΔG = ΔH - TΔS

• ΔG^θ = -24.9 kJ.mol^-1

• ΔG^θ = 24.9 kJ.mol^-1

• ΔG^θ = -29.9 kJ.mol^-1

• ΔG^θ = 29.9 kJ.mol^-1

Answer explanation

Answer Explanation

Determine the rate of reaction at 40s.

• Rate = 0.000000170

• Rate = 0.000170

• Rate = 0.0000170

• Rate = 0.00170

Answer explanation

Answer Explanation

Use the graph that the overall reaction is first order. Choose the correct explanation for this answer.

• 1st order because constant half-lives and constant time between halving of concentration

• 1st order because constant half-lives but increasing time between halving of concentration

• 1st order because constant half-lives but decreasing time between halving of concentration

• 1st order because half-lives is not constant and inconsistent time between halving of concentration

Answer explanation

Answer Explanation

Calculate the rate constant k for this reaction along with its units.

Remember: k=0.693/t½

• k = 0.00433 s^-1

• k = 0.0433 s^-1

• k = 0.433 s^-1

• k = 0.000433 s^-1

Answer explanation

Answer Explanation

The potential difference when a half-cell is connected to a (standard) hydrogen electrode under standard conditions is defined as:

• Standard Electrode Potential

• Hydrogen Cell EMF

• Cell Oxidation Potential

• Standard Hydrogen Electrode