Matter, properties of matter : States of matter, change in the state of matter and MCQs for GPAT, NIPER, Pharmacist and Drug Inspector exam

Matter, properties of matter : States of matter, change in the state of matter and MCQs for GPAT, NIPER, Pharmacist and Drug Inspector exam

Matter: The definition of Matter is anything that has mass and volume (takes up space).

States of matter: Matter exists in one of the three states-solid liquid or gas. Two factors usually determined the state in which matter exist. One is the intensity of intermolecular force and the other is the temperature. Solid have the strongest intermolecular force and the gases have the weakest.

Table – 1 (States of matter)

Sr. No. Solid Liquid Gas
1. A solid’s particles are packed closely together. The forces between the particles are strong enough that the particles cannot move freely, they can only vibrate. As a result, a solid has a stable, definite shape and a definite volume. Solids can only change shape under force, as when broken or cut. A liquid is a fluid that conforms to the shape of its container but that retains a nearly constant volume independent of pressure. The volume is definite (does not change) if the temperature and pressure are constant.

 

Gas molecules have either very weak bonds or no bonds at all, so they can move freely and quickly. Because of this, not only will a gas conform to the shape of its container, it will also expand to completely fill the container.
2. The most important property of the solid state is the high degree of order in which solid substances exist. The molecules of a solid are held together by strong bonds which imparts a high melting point to these substances. In order to their decreasing strengths, these include metallic bonds, ionic bonds, valence bonds and molecular bonds.

There are two types of solid Crystalline Solid and Amorphous Solid.

 

 

 

 

.

 

The liquid state may be considered as an intermediate state as matter goes from the solid state to the gaseous state. Liquid can be considered as highly compressed gases or slightly released solids. The molecules of a gas are in a state of constant motion owning to their kinetic energy which is proportional to the absolute temperature of the gas. The physical behaviour of gaseous is independent of chemical nature of the molecules. Therefore almost all gases respond in an identical way to the variations in pressure, temperature and volume. Since the molecules in a gas are always in a state of vigorous and rapid motion, these travel in random parts, collide with one another and with the wall of the container in which they are confined. These tend to occupy completely all the space available in the container and exert a pressure on the wall of the container.

The general behavior of gases with variation of pressure volume and temperature can be given by the ideal gases equation.

PV =nRT for ‘n’ moles of ideal gas

Where P is the pressure, v is the volume, n is the number of moles of gas, R is a gas constant and T is the absolute temperature.

 

Change in states of matter: Matter can change from one state to another if heated or cooled. If ice (a solid) is heated it changes to water (a liquid). This change is called MELTING. If water is heated, it changes to steam (a gas). This change is called BOILING. The particles of ice, water, and steam are identical, but arranged differently.

  • A solid can transform into a liquid through melting, and a liquid can transform into a solid through freezing. A solid can also change directly into a gas through a process called sublimation.
  • A liquid can be converted to a gas through heating at constant pressure to the substance’s boiling point or through reduction of pressure at constant temperature. This process of a liquid changing to a gas is called evaporation.
  • As the temperature of a solid substance is raised the particles acquire sufficient energy to disrupt the order arrangement and pass into the liquid state. On further increasing the temperature the molecules pass into the gaseous state. In gaseous state the intermolecular forces are reduced to almost negligible.
  • As solid changes to a liquid state and then to gaseous state common heat is absorbed and the at enthalpy heat content of the material increases.
  • The enthalpy of a liquid is greater than that of a solid and the enthalpy of a gas is greater than that of this liquid. The entropy (degree of molecular randomness) of the material also increases as it goes from a solid to a liquid and to gas.

Multiple choice questions (MCQs)

1.Sublimation occurs when

a)a solid changes into a gas

b)a gas changes into a solid

c)a solid changes into a liquid

d)a liquid changes into a gas

2.Which one of the following is not a property of gases?

a)they have definite volume

b)they have no definite shape

c)they can diffuse

d)They have a definite mass

3.The process in which the solid changes directly into vapors without changing in the liquid state is called

a)condensation

b)evaporation

c)boiling

d)sublimation

4.Conversion of a liquid to a gas at all temperatures is called

a)sublimation

b)evaporation

c)condensation

d)boiling

5.The temperature at which the solid starts melting is called

a)boiling point

b)freezing point

c)melting point

d)sublimating point

6.At constant pressure the average kinetic energy of gas molecules increases 2 times if

a)temperature is increased by 2 times

b)temperature is halved

c)no change in temperature

d)temperature remains constant

7.The average kinetic energy of gas molecules is directly proportional to

a)T2

b)√T

c)T

d)2T

8.The melting and freezing of a substance occurs at

a)same temperature

b)more than melting point

c)more than freezing point

d)less than boiling point

9.If the liquid is heated to increase the kinetic energy then the liquid will

a)evaporate slowly

b)evaporate faster

c)not evaporate

d)boil

10.The process in which the vapor molecules are recaptured by the molecules at the liquid surface is called

a)evaporation

b)sublimation

c)condensation

d)boiling

11.As the molecular mass of gases increases their density

a)decreases

b)increases

c)remains constant

d)none of above

12.The position of liquid molecules are

a)fixed

b)not fixed

c)not sliding

d0none of above

13.Boiling point is the temperature at which vapor pressure is

a)more than external pressure

b)less than external pressure

c)not related to external pressure

d)equal to external pressure

14.If the temperature of any gas is increased its volume

a)increases

b)decreases

c)remains same

d)none of above

15.Which factors usually determined the state in which matter exist?

a)intermolecular force

b)temperature

c)both of these

d)none of these

Solutions:

  1. a) A solid changes into a gas
  2. a) They have definite volume
  3. d) Sublimation
  4. b) Evaporation
  5. c) Melting point
  6. a) Temperature is increased by 2 times
  7. c) T
  1. a) Same temperature
  2. b) Evaporate faster
  3. c) Condensation
  4. b) Increases
  5. b) Not fixed
  6. d) Equal to external pressure
  1. a) Increases

15. c)both of these

References:

1. GAURAV KUMAR JAIN – THEORY & PRACTICE OF PHYSICAL PHARMACY, 1st edition 2012 Elsevier, page no. 1-17.

2. Martins Physical Pharmay, 6th edition 2011, page no. 39-49.

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