Tag: introduction to thermodynamics

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Multiple choice chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

Select the correct statements.

  1. State of a system is assumed to be in internal equilibrium and the temperature and pressure are uniform throughout the system.

  2. Thermal drift in a system with time is more in Dewar flask than in insulated system.

  3. Thermal drift in a system with time is more in non-insulated system than in insulated system.

  4. Thermal drift in a system with time is more in insulated system than in non-insulated system.
Reveal answer Fill a bubble to check yourself
A,C Correct answer
Multiple choice chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics
Which of the following is not a state function?

  1. Temperature

  2. Density

  3. Work

  4. Volume

  5. Pressure
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Temperature, density, volume and pressure are state functions.
They are intrinsic properties of the system. Their values  depend on initial and final state only and are independent of path followed.
On the other hand, work is a path function. It is not an state function. Its value depends on the path followed.

Multiple choice chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

Select the conditions which represent the criteria for spontaneity of a process in a closed system, from the following given conditions:


Serial Number Conditions
1. ${ \left( dG \right)  } _{ P,T }>0$
2. ${ \left( \Delta S \right)  } _{ universe }>0$
3. ${ \left( dU \right)  } _{ S,V }>0$
4. ${ \left( dH \right)  } _{ S,P }<0$
5. ${ \left( dS \right)  } _{ u,V }<0$
6. ${ \left( dS \right)  } _{ H,P }>0\quad $

  1. 1 & 4

  2. 1 & 2

  3. 3 & 5

  4. 4 & 6
Reveal answer Fill a bubble to check yourself
B Correct answer
Multiple choice chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

Which of the following factors is of no significance for roasting sulphide ores to the oxides and not subjecting the sulphide ores to carbon reduction directly?

  1. Metal sulphides are thermodynamically more stable than $CS _2$
  2. $CO _2$ is thermodynamically more stable than $CS _2$

  3. Metal sulphides are less stable than the corresponding oxides
  4. $CO _2$ is more volatile than $CS _2$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The reduction of metal sulfides by carbon reduction process is not spontaneous as the change in Gibb's free energy ($\triangle G$) for such a process is positive. 

The reduction of metal oxides by carbon reduction process is spontaneous as $\triangle G$ for such a process is negative.
Thus $CO _2$ is more stable than $CS _2$ and the metal sulfides are more stable than the corresponding oxides.
Hence, factor listed in $(3)$ is of no. significance.