Tag: chemistry

Questions Related to chemistry

A well stoppered thermoflask contains some ice cubes. This is an example of:

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

  1. closed system

  2. open system

  3. isolated system

  4. non-thermodynamic system

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Correct Option: A

When a volatile liquid is introduced into an evacuated closed vessel at a particular temperature, both evaporation and condensation take place simultaneously. The system reaches equilibrium state when:

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

  1. the liquid is completely transformed into the corresponding vapour

  2. equal amounts of liquid and vapour are present in the system

  3. the rate of evaporation becomes equal to the rate of condensation

  4. liquid cannot be converted into vapour and vice versa.

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Correct Option: C
Explanation:
Solution:- (C) The rate of evaporation becomes equal to the rate of condensation
As we know that the equilibrium in a system is established when rate of forward reaction is equal to the rate of backward reaction.
Hence the rate of evaporation becomes equal to the rate of condensation.

Both q and w are ______ function and $q+w$ is a ______ function.

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

  1. state, state

  2. state, path

  3. path, state

  4. path, path

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Correct Option: C
Explanation:

Answer $C: $Path, state.

The change in energy of a system is equal to the difference between the heat added to the system and the work done by the system.
$\triangle E=Q-W$ ($W$ is $-ve$, if work done on system)
$Q$ and $W$ are path dependent, but $\triangle E$ depends only on the state of the system and not how the system got to that state.

A well stoppered thermos flask contains some ice cubes. This is an example of:

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

  1. closed system

  2. open system

  3. isolated system

  4. non-thermodynamic system

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Correct Option: C
Explanation:

An isolated system is a thermodynamic system that can not exchange either energy or matter outside the boundaries of the system.

Thus, a well stopped thermos flask containing ice an example for isolated system.

Which of the following is a path function?

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

  1. Internal Energy

  2. Enthalpy

  3. Work

  4. All of the above

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Correct Option: C
Explanation:
Path functions are properties or quantities whose values depend on the transition of a system from the initial state to the final state. The two most common path functions are heat and work

A physical quantity is said to be state function if its value depends only upon the state of the system and does not depend upon the path by which this state has been attained. E.g pressure, volume, temperature

Which of the following statement is false?

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

  1. Work is a state function.

  2. Temperature is a state function.

  3. Change of state is completely defined when initial and final states are specified.

  4. Work appears at the boundary of the system.

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Correct Option: A
Explanation:

Work is not a state function. It is path function. Its value depends on the path chosen to reach a particular state.

Which of the following are state property?

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

  1. Internal energy (U)

  2. Volume (V)

  3. Heat (q)

  4. Enthalpy (H)

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Correct Option: A,B,D
Explanation:

Internal energy, volume and enthalpy are state properties. Their values are independent of  the path chosen to reach a particular state.
Heat is a path function. Its value depends on the path chosen to reach a particular state.

Identify the state quantity among the following

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

  1. q

  2. q-w

  3. q+w

  4. q/w

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Correct Option: B,C
Explanation:

Both work and heat are path functions. Their values depends on the path chosen to reach a particular state.
However, the change in internal energy is equal to the sum of heat and work. It is a state function. Its value is independent of  the path chosen to reach a particular state.

Identify the state functions.

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

  1. $S$

  2. $q$

  3. $w$

  4. $q+w$

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Correct Option: A,D
Explanation:

Both work and heat are path functions. Their values depends on the path chosen to reach a particular state.
However, the change in internal energy is equal to the sum of heat and work. It is a state function. Its value is independent of  the path chosen to reach a particular state.
Entropy is a state function.  Its value is independent of  the path chosen to reach a particular state.

Which of the following is/are state property/properties?

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

  1. Internal energy

  2. Volume

  3. Heat

  4. Enthalpy

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Correct Option: A,B,D
Explanation:

Heat is a path dependent function.
While internal energy, volume and enthalpy depend only on initial and final stages.
So, these are state properties.