Ellingham diagrams and thermodynamics of reduction

28 questions on Ellingham diagrams and thermodynamics of reduction from the Metallurgy chapter: 6 NEET level, 11 JEE Main, 11 JEE Advanced. Each one opens with its answer and solution.

• In the Ellingham diagram, which of the following lines has a negative slope? NEET level
• In an Ellingham diagram of Delta G deg against T (per mole of O2), a metal whose oxide line lies lower than that of a second metal NEET level
• Most metal oxide lines in the Ellingham diagram slope upward with temperature because NEET level
• Which of the following reactions is an example of calcination? NEET level
• Reduction of metal oxides such as Cr2O3 with powdered aluminium is known as NEET level
• The main reducing agent for iron oxides in the upper part of the blast furnace is NEET level
• In the Ellingham diagram, the line for C + O2 -> CO2 is almost horizontal because JEE Main level
• On an Ellingham diagram the line for 2C + O2 -> 2CO crosses the line of a metal oxide MO at a temperature T_0. For T > T_0 JEE Main level
• The lines for 2C + O2 -> 2CO and 2CO + O2 -> 2CO2 intersect at about 983 K in the Ellingham diagram. Which statement is correct? JEE Main level
• The Delta G deg-T line for 2Zn + O2 -> 2ZnO shows a sudden increase in slope at 1180 K (the boiling point of zinc). The reason is that JEE Main level
• Assertion (A): Silver oxide and mercury(II) oxide can be decomposed to the metals simply by heating. Reason (R): The Delta G deg of formation of these oxides be... JEE Main level
• Match the metal in List I with the usual method of obtaining it in List II. List I: (A) Iron; (B) Aluminium; (C) Mercury; (D) Copper from Cu2S. List II: (p) Ele... JEE Main level
• At 1000 K, Delta G deg per mole of O2 for formation of oxides is (in kJ): Al2O3 -1053; MgO -1090; Cr2O3 -600; FeO -420; Cu2O -240. Aluminium can reduce which of... JEE Main level
• The Delta G deg for 2C + O2 -> 2CO is -221 - 0.179 T kJ per mole of O2. At 1000 K the values of Delta G deg (kJ per mole of O2) for formation of some oxides are... JEE Main level
• At 1400 K (above the boiling point of zinc), take Delta G deg = -930 + 0.405 T kJ for 2Zn(g) + O2 -> 2ZnO(s) and Delta G deg = -221 - 0.179 T kJ for 2C + O2 -> ... JEE Main level
• Take Delta G deg = -529 + 0.131 T kJ for 2Fe + O2 -> 2FeO and Delta G deg = -221 - 0.179 T kJ for 2C + O2 -> 2CO. Reduction of FeO by carbon, FeO + C -> Fe + CO... JEE Main level
• Which of the following statements about the Ellingham diagram are correct? JEE Main level
• A partly roasted copper matte contains 3.00 mol of Cu2O and 2.00 mol of Cu2S, which undergo self-reduction, 2Cu2O + Cu2S -> 6Cu + SO2, with no external reductan... JEE Advanced level
• For 2Zn(g) + O2 -> 2ZnO(s) (T above 1180 K, the boiling point of Zn) take Delta G deg = -930 + 0.405 T kJ, and for 2C + O2 -> 2CO, Delta G deg = -221 - 0.179 T ... JEE Advanced level
• At 1000 K, Delta G_f deg values are: Al2O3 -1582 kJ mol^-1 and Cr2O3 -1058 kJ mol^-1. For the thermite reaction Cr2O3 + 2Al -> Al2O3 + 2Cr carried out on 38.0 g... JEE Advanced level
• At 1500 K, Delta G deg per mole of O2 for oxide formation is (kJ): MgO -880; Al2O3 -840; Cr2O3 -540; FeO -380; ZnO -320. For 2C + O2 -> 2CO, Delta G deg = -221 ... JEE Advanced level
• Using Delta G_f deg at 298 K (kJ/mol): Fe2O3 -742.2; CO -137.2; CO2 -394.4, calculate Delta G deg and log_10K for Fe2O3 + 3CO -> 2Fe + 3CO2 at 298 K (R = 8.314 ... JEE Advanced level
• At 1000 K, Delta G deg per mole of O2 (kJ): CaO -1150; Al2O3 -1053; MnO -690; NiO -310; Ag2O +60. For 2C + O2 -> 2CO, Delta G deg = -221 - 0.179 T kJ. Which sta... JEE Advanced level
• Which statements about iron extraction in the blast furnace are correct? JEE Advanced level
• Which statements about extraction of copper from copper pyrites (CuFeS2) and similar ores are correct? JEE Advanced level
• An ore X on roasting in excess air gives a pungent colourless gas and a white oxide (yellow when hot) that dissolves in both acids and alkalis. The oxide is hea... JEE Advanced level
• 500 kg of bauxite contains 60.0% Al2O3. The Baeyer leaching step recovers 85.0% of the alumina as pure Al2O3, and electrolysis in the Hall-Heroult cell converts... JEE Advanced level
• For 4/3 Al + O2 -> 2/3 Al2O3 take Delta G deg = -1115 + 0.210 T kJ. For 2Mg(g) + O2 -> 2MgO(s) (T above 1363 K, the boiling point of Mg) take Delta G deg = -145... JEE Advanced level