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FFTCDHH

This document discusses different phases of matter and phase changes. It defines solids, liquids, and gases, and describes their characteristics in terms of molecular motion and arrangement. It then explains several types of phase changes - melting, freezing, evaporation, condensation, sublimation, and deposition - and whether each process is endothermic or exothermic using kinetic molecular theory. Melting, freezing, evaporation, and sublimation are endothermic, while condensation and deposition are exothermic.

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77 views2 pages

FFTCDHH

This document discusses different phases of matter and phase changes. It defines solids, liquids, and gases, and describes their characteristics in terms of molecular motion and arrangement. It then explains several types of phase changes - melting, freezing, evaporation, condensation, sublimation, and deposition - and whether each process is endothermic or exothermic using kinetic molecular theory. Melting, freezing, evaporation, and sublimation are endothermic, while condensation and deposition are exothermic.

Uploaded by

Craft City
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© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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NAME: ____________ ROLL NO.

: ____________
Hi 9 Assignment 1 Chap 2 –Phase change
GRADE: __________
Date:13.7.2020 ,DOS:15.7.2020
SUBJECT: Chemistry TEACHER’S SIGNATURE:

Phases of Matter:

Solid • matter that has definite volume and shape.


 • The molecules are packed together tightly and move slowly. 
Liquid • matter that has definite volume but not shape. • 
Since the molecules of a liquid are loosely packed and move with greater speed, 
• a liquid can flow and spread. 
Gas • matter that has indefinite volume or shape. 
• Molecules of a gas are so loosely arranged and move so rapidly that they will fill their
container. 
Phase Change Descriptions:
QUESTION: Using Kinetic molecular theory,explain the following phase change .Also
mention if the process is endothermic or exothermic.

 Melting : Melting point is the temperature at which a solid changes its phase to become a liquid.
In melting particles gain energy and start to vibrate faster and faster. Melting is a Endothermic
process.

Freezing: As a liquid is cooled its molecules lose kinetic energy and their motion slows. When
they've slowed to where intermolecular attractive forces exceed the collisional forces from
random motion, then a phase transition from liquid to solid state takes place and the material
freezes.
Freezing is a Endothermic process.

Evaporation: When particles in the liquid phase are heated, they gain kinetic energy and move
faster and further apart. Eventually they have enough energy to escape the forces of attraction
holding them together in the liquid phase and they move very fast and far from each other and
exist in the gaseous phase. Evaporation is a Endothermic process

Condensation : As heat is removed from a gas, the molecules of the gas move more slowly, and
as a result, the intermolecular forces are strong enough to pull the molecules together to form
droplets of liquid.
Condensation is a Exothermic proccess.

1
Sublimation : Sublimation is the process of going from a solid to a gas. In sublimation the
energy is taken in. When heat energy is absorbed by some of the moleculed,the acquire much
higher energy than their energy than their neighbours and their by over come the forces of
attraction and escape intk the valor phase. Since this requires additional energy, it is called as
an Endothermic reaction

Deposition : Deposition is the process by which molecules go directly from the gas phase into
the solid phase. Deposition chemistry occurs when molecules settle out of the gas phase and
into the solid phase. Deposition is an Exothermic proccess.

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