At a temperature above 1073 K, coke can be used to reduce FeO to Fe. It can be best explained by:
1. Ellingham diagram.
2. Orgel diagram.
3. Tunabo-Sugano diagram.
4. Born-Haber cycle.
The thermodynamic property useful for selecting the reducing agent is:
1. Gibbs free energy change .
2. Internal energy change.
3. Specific heat capacity.
4. None of the above.
Consider the Ellingham diagram given below.
The Y-axis, and X-axis in the graph are respectively:
1. Gibbs energy(\(\Delta G_{r}^{o} \)), and Pressure
2. Gibbs energy (\(\Delta G_{r}^{o} \)), and temperature
3. Enthalpy(\(\Delta H_{r}^{o} \)), and temperature
4. Temperature, and Gibbs energy (\(\Delta H_{r}^{o} \))
The correct statement among the following is:
1. | In the decomposition of oxide into oxygen and gaseous metal, entropy increases. |
2. | Decomposition of oxide is an endothermic change. |
3. | To make ∆G° negative, the temperature should be high enough so that T∆S° > ∆H°. |
4. | All of the above. |
Ellingham's diagram for the formation of is a straight line in the given graph.
This is due to:
1. Increase in entropy during formation.
2. Decrease in entropy during formation.
3. Entropy remains constant during formation.
4. Can not be predicted.
A metal's oxide that can be reduced by Fe as a reducing agent at a temperature is:
1. Zr
2. Ca
3. Mg
4. None of the above.
The correct statement among the following is:
1. | The rate of reaction cannot be understood from the Ellingham diagram. |
2. | During the formation of metal oxide \(\Delta S\) becomes negative and \(\Delta G\) becomes positive resulting in a positive slope. |
3. | There is an abrupt change in the slope of the Ellingham line when a change in phase (s→l) or (l→g) takes place. |
4. | All of the above. |
Al can reduce MgO under the following conditions:
1. Above 500 °C, Al can reduce MgO
2. Below 500 °C, Al can reduce MgO
3. Below 1350 °C, Al can reduce MgO
4. Above 1350 °C, Al can reduce MgO
Which of the following has a negative slope?
1. C CO
2. Fe Fe2O3
3. Mg MgO
4. All of the above
Consider the following graph.
At 1400 oC, the \(\Delta G_{r}^{o}\) the value for the reaction
2FeO + 2C → 2Fe + CO is
1. -116 kJ mol-1
2. -106 kJ mol-1
3. 100 kJ mol-1
4. -100 kJ mol-1