If an ideal gas does positive work on its surroundings, we may assume, with regard to the gas:
A. Volume increases
B. Internal energy decreases
C. Pressure decreases
D. Temperature increases
E. Pressure increases
To answer this question, we need to understand the relationship between work done by a gas and its properties.
Work done by a gas on its surroundings occurs when the gas expands, pushing the surroundings, such as a piston, against an external pressure. This work done by the gas can be positive, meaning it is happening in the direction of the surroundings, or negative if the work is done on the gas by the surroundings.
Now let's analyze each option:
A. Volume increases: When an ideal gas expands, it increases its volume as the gas particles spread out. This expansion is necessary for the gas to do work on its surroundings when the pressure on the gas is greater than the pressure on the surroundings. Thus, this statement can be true.
B. Internal energy decreases: Internal energy refers to the total energy of a system, including the kinetic and potential energy of its particles. The work done by the gas is not directly related to the internal energy of the gas. Therefore, we cannot assume that the internal energy decreases based on the work done by the gas. This statement is not necessarily true.
C. Pressure decreases: Work done by a gas on its surroundings is typically associated with the expansion of the gas, which leads to a decrease in pressure. So, this statement can be true.
D. Temperature increases: The relationship between work done and the temperature of the gas is not straightforward. The temperature of an ideal gas depends on the average kinetic energy of its particles, which can change due to factors other than work done, such as heat transfer. So, we cannot directly assume that temperature increases solely based on work done. This statement is not necessarily true.
E. Pressure increases: As explained earlier, work done by the gas on its surroundings is usually associated with a decrease in pressure. Thus, this statement is not true.
In conclusion, based on the given options, we can assume that if an ideal gas does positive work on its surroundings, the volume increases (option A) and the pressure decreases (option C).
If an ideal gas does positive work on its surroundings, we may assume that the gas is expanding and doing work against an external force. In this scenario, the correct answer would be:
A. Volume increases
When a gas expands, its volume increases as it pushes against the external force. This means that the gas is doing work on its surroundings, which is why the work is positive.
To do positive work, you must push in the direction of motion. That requires an increase of volume as the walls of the balloon move out :)
It could be that the internal energy decreases at the same time but you might be putting heat in.