Physical chemistry and transition elements

What are the units of Kc for N₂(g) + 3H₂(g) ⇌ 2NH₃(g)?

What is the pH of 0.010 mol dm⁻³ HCl(aq)?

What is the value of Kw at 298 K?

Which ion has the electron configuration [Ar]3d⁵?

Which change has the most positive entropy change?

rate = k[A]²[B]. What are the units of k?

Which ion gives a blue precipitate with NaOH(aq)?

0.500 mol H₂ and 0.500 mol I₂ were heated in a sealed 2.00 dm³ vessel. At equilibrium 0.780 mol HI was present. H₂(g) + I₂(g) ⇌ 2HI(g) Calculate Kc.

For N₂O₄(g) ⇌ 2NO₂(g) at equilibrium the total pressure is 200 kPa and the mole fraction of NO₂ is 0.40. Calculate Kp.

The table shows initial rates for 2A + B → products.

Exp	[A] / mol dm⁻³	[B] / mol dm⁻³	Rate / mol dm⁻³ s⁻¹
1	0.10	0.10	2.0 × 10⁻⁴
2	0.20	0.10	8.0 × 10⁻⁴
3	0.10	0.30	6.0 × 10⁻⁴

Determine the rate equation and calculate the rate constant with units.

Calculate the pH of 0.0250 mol dm⁻³ Ba(OH)₂(aq).

Calculate the pH of 0.100 mol dm⁻³ ethanoic acid (Ka = 1.75 × 10⁻⁵ mol dm⁻³), and state one approximation you made.

10.0 cm³ of 0.100 mol dm⁻³ NaOH is added to 25.0 cm³ of 0.100 mol dm⁻³ ethanoic acid. Calculate the pH of the buffer formed.

Calculate the lattice enthalpy of potassium chloride. ΔfH(KCl) −437; atomisation K +89; 1st IE K +419; atomisation Cl +122; 1st EA Cl −349 (kJ mol⁻¹)

The enthalpies of hydration of K⁺ and Cl⁻ are −322 and −378 kJ mol⁻¹. Calculate the enthalpy change of solution of KCl.

ΔS for dissolving KCl is +75 J K⁻¹ mol⁻¹. Use ΔG to show that KCl dissolves at 298 K even though the process is endothermic, and explain the role of entropy.

10.0 cm³ of bleach was diluted to 250 cm³. 25.0 cm³ of this was added to excess acidified KI. The iodine released needed 18.60 cm³ of 0.0500 mol dm⁻³ Na₂S₂O₃. ClO⁻ + 2I⁻ + 2H⁺ → Cl⁻ + I₂ + H₂O I₂ + 2S₂O₃²⁻ → 2I⁻ + S₄O₆²⁻ Calculate the concentration of ClO⁻ in the original bleach.

Write the half-equations at each electrode and the overall equation for an alkaline hydrogen–oxygen fuel cell.

Describe the stereoisomerism shown by transition metal complexes, using [Pt(NH₃)₂Cl₂] and [Ni(NH₂CH₂CH₂NH₂)₃]²⁺ as examples, and explain how cisplatin acts as an anticancer drug.

Describe what you would see when aqueous sodium hydroxide is added dropwise and then in excess to a solution containing Cr³⁺(aq), and give the formula of the final complex. State what forms instead with excess aqueous ammonia.

Marble chips (in excess) reacted with 50.0 cm³ of hydrochloric acid. Figure 1 shows the volume of CO₂ collected. Use the graph to determine the initial rate of reaction.

Concentrated HCl is added to aqueous copper(II) sulfate. Write an equation and describe the changes in colour, shape and coordination number.

4.90 g of ammonium iron(II) sulfate, (NH₄)₂Fe(SO₄)₂·xH₂O, was dissolved and made up to 250 cm³. 25.0 cm³ portions needed 12.50 cm³ of 0.0200 mol dm⁻³ KMnO₄. MnO₄⁻ + 8H⁺ + 5Fe²⁺ → Mn²⁺ + 5Fe³⁺ + 4H₂O Determine x.

Explain why ethanoic acid gives a less exothermic value.

For ZnO(s) + C(s) → Zn(s) + CO(g), ΔH = +238 kJ mol⁻¹ and ΔS = +285 J K⁻¹ mol⁻¹. Calculate the minimum temperature for the reaction to be feasible and explain why ΔS is positive.

Figure 2 shows the pH curve when 25.0 cm³ of a weak acid HA was titrated with 0.100 mol dm⁻³ NaOH. Use the curve to find pKa and Ka.

Explain whether phenolphthalein (pH 8.2–10.0) or methyl orange (pH 3.1–4.4) should be used for this titration.

Calculate the pH after 40.0 cm³ of NaOH has been added.

N₂(g) + 3H₂(g) ⇌ 2NH₃(g), ΔH = −93 kJ mol⁻¹. Explain why a temperature of about 450 °C and an iron catalyst are used.