Question

In a reversible process the system absorbs 600 kJ heat and performs 

         250 kJ  work by the surroundings. What is the increase in the internal 

         energy of the system?

        (a) 850 kJ                       (b) 600 kJ

        (c) 350 kJ                       (d) 250 kJ

​

Answer 1

Given:

In a reversible process, the heat absorbed by the system = 600 kJ

The work done by the surroundings = 250 kJ

To Find:

The increase in the internal energy of the system

Solution:

The internal energy of the system increases by (c) 350 kJ.              

The First Law of Thermodynamics is a mathematical formula based on the conservation of energy. It says that energy can neither be created nor be destroyed.

Mathematically,

∆U = Q + W

Here, ∆U shows the change in internal energy of the system

Q represents the heat exchanged during the process and W represents the work done.

Since in the question, the work is performed by the system, W has a negative sign.

Substituting the values,

∆U = 600 + (– 250) kJ

= 600 - 250 kJ

= 350 kJ

Answer 2

Answer:

The internal energy of the system increases by (c) 350 kJ.  

Step by Step explanation:

• In context to the given question, we have to the increase in the internal energy of the system

• Given:

1. The heat absorbed by the system (Q) = 600 kJ
2. The work done by the system (W) = 250 kJ

• To Find:

1. The increase in the internal energy of the system

The First Law of Thermodynamics says that the change in internal energy of  a system equals the net heat transfer into system minus the net work done by the system

Mathematically,

∆U = Q + W

In which,

∆U = change in internal energy of the system

Q = heat exchanged during the process

W = work done.

As the work is performed by the system, W will have negative sign because work energy is given to the surrounding

Substituting the values,

∆U = 600 + (– 250) kJ

= 600 - 250 kJ

= 350 kJ

Therefore, the increase in the internal energy of the system is 350kJ.