Question

Which of the following phase changes is an exothermic change?

Answer 1

$\boxed{{\text{B}}{\text{. Deposition}}}$ is an exothermic change.

Further Explanation:

Phase change:

The phase change is defined as the change from one state to another state without altering its chemical composition. It is also known as a phase transition, state change or physical change.

Phase changes are of two types:

1. Endothermic change: These changes take up energy from the surroundings, usually in the form of heat. For example, melting of ice is an endothermic phase change. It involves the change of solid state (ice) to the liquid state (water). Energy is to be supplied for this process and therefore it is an endothermic process.

2. Exothermic change: These changes release energy or heat to the surrounding environment. For example, freezing of water. It involves the conversion of liquid state (water) to the solid state (ice). Here, energy is released for this process and that’s why it is an exothermic process.

(A) Sublimation: It is the conversion of a substance directly from solid to vapor phase, without going through the liquid state. Naphthalene and dry ice are substances that undergo sublimation. The forces between the solid particles are very strong. In order to convert it into the gas phase, energy is to be supplied from the surrounding environment. So sublimation is an endothermic process.

(B) Deposition: It is the phase transition in which the vapors are directly converted into solid-state, without passing through the liquid intermediate. It is just the reverse of sublimation and is therefore known as desublimation. The gas particles have a high degree of randomness and the least intermolecular forces in them. So its particles move in all directions with high speed. In order to convert them into the solid-state, their motion needs to slow down and for this, energy is released. So deposition is an exothermic process.

(C) Vaporization: It is the phase transition that converts the liquid into vapors. In order to change the liquid state to the vapor state, the temperature is to be increased or heating is done. Heat is supplied to the system from the surrounding environment. So vaporization is an endothermic process.

(D) Melting: It is the phase transition that results in the conversion of solid-state to the liquid state. Since the solid particles have stronger intermolecular forces between them as compared to that in liquids. In order to overcome such strong forces, energy is supplied in the form of heat and therefore melting is an endothermic process.

Learn more:

1. Identify the phase change in which crystal lattice is formed: brainly.com/question/1503216

2. The main purpose of conducting experiments: brainly.com/question/5096428

Answer details:

Grade: Senior School

Subject: Chemistry

Chapter: Phase transition

Keywords: exothermic, endothermic, sublimation, deposition, vaporization, melting, phase transition, phase change, state change, physical change, solid state, liquid state, vapor state.

Answer 2

The phase change that is an exothermic process is B. deposition. It is an exothermic process because it requires a release of heat to change from one phase to the other.

FURTHER EXPLANATION

Some changes in state are exothermic process while others are endothermic.

Exothermic Process

• Exothermic processes release heat to the surroundings.
• The release of heat causes the particles of the substance to move slower and have less energy. Less energetic collisions of the particles results in the particles sticking to each other because there isn't sufficient energy to overcome the attractive forces acting on them.
• This results in the warming up of the surroundings which includes the container holding the substance.

Endothermic Process

• Endothermic processes are processes that absorb heat from the surroundings.
• When particles absorb heat, they start to move faster and spread out.
• With the additional energy, the particles move faster and are able to overcome the attractive forces holding them together.
• This causes a cooling of the surrounding or the container.

A) Sublimation

Sublimation is phase change from solid to gas without passing through the liquid state. For the closely packed particles of the solid to spread out and change to its gaseous state, they must absorb heat. Therefore, this process is endothermic.

B) Deposition

This is the process of changing from gas to solid state without passing through the liquid state. For the particles of the gas to turn to solid, they must lose their energy so that when they collide with each other the attractive forces will hold them together forming the solid. This is an example of an exothermic process.

C. Vaporization

Particles of a vapor are farther away from each other than the particles of liquids. Liquids, therefore, need to be heated to turn them into gas or vapor. Since it requires absorption of heat, this is endothermic.

D. Melting

Solid particles are more closely packed than liquids. They are held by strong attractive forces that keep their movement limited to vibration in place. To change solids to liquids, their attractive forces must be overcome by heating. Absorption of heat makes the particles vibrate harder and overcome the attractive forces holding the solid together.

LEARN MORE

• Endothermic processes brainly.com/question/12979983
• Enthalpy  brainly.com/question/1127247
• Heat of Vaporization brainly.com/question/12984871

Keywords: phase change, exothermic , endothermic