STATE OF MATTER

STATE OF MATTER

from Femosky110 on 06/12/2020 01:15 PM

STATE OF MATTER
Matter in the solid state has a definite volume and shape, with essential particles within the matter -atoms, molecules or ions very close together and fixed into definite position. Matter in the liquid state has a definite volume, with a changeable shape. It easily settles in to fit the shape of its container. Its particles are still close together but move about freely. Matter in the gaseous state does not have a definite shape or volume. It has both variable volume and shape, and adapts to fit its container. Its particles are not close together. They are as well not fixed in place. Matter in the plasma state exhibits variable volume and shape, but like neutral atoms, it possesses a considerable number of ions and electrons, both of which can travel around freely. Plasma is the most widespread form of observable matter in the world.

 

Kinetic Theory of Matter
The Kinetic Theory of Matter states that matter is made up of a large number of small particles - individual atoms or molecules that are in continuous motion. This theory is as well known as the Kinetic Molecular Theory of Matter and the Kinetic Theory.

By making a number of simple assumptions, like the idea that matter is made of extensively spaced particles in constant motion, the theory tries to give explanation to the behavior of matter. Two significant areas elucidated are the gush or transmission of heat and the association between pressure, temperature, and volume properties of gases.

Possible Questions you may be asked:

• What are the assumptions of the kinetic theory of matter?

• How does the theory explain heat flow?

• How does the kinetic theory of matter explain pressure and volume?

Assumptions of kinetic theory
The Kinetic Theory of Matter is a guess of how matter ought to behave, based on definite assumptions and estimations. The assumptions are derived from observations and experiments, like the fact that materials consist of small molecules or atoms. Approximations are made to keep the theory from being too complex. One assumption is that the size of the particles is so small that it can be considered a point.

Matter consists of small particles

The number 1 assumption of this theory is that matter consists of a huge number of very small particles that could either be individual atoms or molecules.

Large separation between particles
The second assumption of the theory deals with the disconnection of the particles.

• In a gas, the distance between particles is very large compared to their size, to such extent that there are no attractive or repulsive forces between the molecules of a gas.

• In a liquid, although the particles are still far apart, they are close enough to allow attractive forces lock up the materials to the shape of its container.

• In a solid, the particles are very closely knit together that the forces of attraction shut in the material to a definite shape.

Particles in continuous motion
The third assumption is that all the particles are in continuous motion.

In gases, the motion of the particles is assumed to be haphazard and free. In liquids, the motion is fairly inhibited by the volume of the liquid. In solids, the motion of the particles is strictly confined to a small space, in order for the solid to maintain its shape.

The velocity of each particle determines its kinetic energy.

Collisions transfer energy
The numerous particles often collide with each other. Also, if a gas or liquid is confined in a container, the particles collide with the particles that make up the walls of a container.

Approximations
When atoms or molecules collide, energy may be given off in the form of electromagnetic radiation. Taking this into account could make the theory highly complex, and since the amount of radiation is small in most situations, an approximation is made that this effect is negligible.

Also, atoms and molecules have a discrete size. But charting the collisions of such particles would again make the theory too complex. Thus an approximation is made to say the size of the particles is a simple point, especially compared to the distances involved.

No energy change
Thus, an assumption is that the particles transfer energy in a collision with no net energy change. That means the collisions between the particles are perfectly elastic and no energy is gained or lost during the collision. This follows the Law of the Conservation of Energy.

In reality, the collisions are not perfect, and some energy is lost. But for the sake of simplicity in drawing conclusions, this theory makes the collisions elastic.

Thermal energy and heat flow
The motion of a particle determines its kinetic energy, according to the equation

KE = 1/2MV2

where

• KE is the kinetic energy of the particle

• m is its mass

• V2 is the square of its velocity

The total internal kinetic energy of all the particles is called its thermal energy.

The temperature of an object or collection of matter is the average kinetic energy of the particles. Faster particles means a higher temperature. A thermometer is used to measure the temperature and put it into temperature degrees instead of kinetic energy units.

The heat is the transfer of thermal energy from an object of higher temperature to one of lower temperature. For example, an object feels warm or hot if its temperature is higher than your skin temperature.

The Kinetic Theory of Matter explains heat transfer by conduction, where thermal energy seems to move through a material, warming up cooler areas. This is called heat transfer or heat flow

Processes not covered in this theory are heat transfer by convection and by radiation.

chemistry
Collisions transfer energy
The Kinetic Theory of Matter states that the material's particles have greater kinetic energy and are moving faster at higher temperatures. When a fast moving particle collides with a slower moving particle, it transfers some of its energy to the slower moving particle, increasing the speed of that particle.

If that particle then collides with another particle that is moving faster, its speed will be increased even more. But if it hits a slow moving particle, then it will speed up the third particle.

With billions of moving particles colliding into each other, an area of high energy or high heat will slowly diffuse across the material, making other areas warm too. By the Conservation of Energy, the total energy or total heat of the object will remain the same, but the heat will be evenly distributed throughout the object.

Rate of transfer
The rate at which the kinetic or thermal energy is transferred from one particle to another depends on the separation of the particles and their freedom to move.

In a gas, the particles are allowed to move freely, but their separation distance is great, so heat or energy transfer is slow. In a liquid, the heat transfer by conduction is faster because the particles are closer together.

In a solid, the molecules are constrained into a specific location within the material. Although the particles are closer together than in liquids, the constraints in some materials actually prevent the transfer of heat energy. A good example of that is in wood.

Temperature
One important result of the kinetic theory is that the average molecular kinetic energy is proportional to the absolute temperature of the material. Absolute temperature is measured in the Kelvin scale. But in general, you can say that temperature is the measurement of the average internal kinetic energy of the material or object.

Pressure, volume and temperature
If a gas is enclosed in a container, it exerts pressure on the walls of the container. The Kinetic Theory of Matter explains gas pressure as the total force exerted by gas molecules colliding against the walls of a container.

If the container can expand, like with a balloon or cylinder and piston, increasing the pressure can increase the volume. Like, the balloon will get bigger. Also, if you increase the temperature of the gas--and thus the kinetic energy of its molecules—you increase the pressure or the volume of the container.

This leads to a relationship between pressure, volume and temperature in an ideal gas. (An ideal gas is a gas that follows the assumptions of the Kinetic Theory of Matter.) The relationship is

PV = NkT

where:

• P is the pressure of the ideal gas

• V is the volume of the gas container

• N is the number of gas particles

• k is the Boltzman constant in joule per kelvin per particle

• T is the temperature in the absolute or kelvin scale

This equation has a number of implications, including:

• If you decrease the pressure and hold the volume constant, the temperature decreases (principle of a refrigerator)

• If you increase the temperature and hold the pressure constant, the volume increases (heating a balloon)

• Kinetic Molecular Theory of Matter

• I. Kinetic Theory of Matter is theory that explains the effects of temperature and pressure on matter

A. 3 Postulates

1. All matter is made up of tiny particles.

2. These particles are in constant motion.

3. Collisions between these particles are perfectly elastic.

• B. Four States of Matter

1. Solid

2. Liquid

3. Gas

4. Plasma

• II. Gases

A. Distinguishing Properties of Gases

1. Gases have no definite shape and no definite volume. They take the shape of their container.

2. Particles move very rapidly in gases.

3. Gases have lower densities thatn solids or liquids because the particles are not as close together.

4. Gases can be compressed because there is alot of space between the particles.

5. They expand when heated.

• B. Gas Pressure

1. A gas exerts a pressure on its container because the gas molecules are constantly colliding with the walls of the container. Each collision exerts a force on the walls of the container.

2. Atmospheric pressure is the pressure that the gases in our atmosphere exert on everything on earth.

Atmospheric pressure is equal to:

a. 101.325 kPa

b. 1 atm

c. 760 mm Hg

d. 760 torr

e. 760 millibars

f. 14.7 lbs/in2

3. Manometer - an instrument used to measure gas pressure.

There are two kinds of manometers:

a. open arm manometer

b. closed arm manometer (also known as a barometer)

C. Motion and Physical States

1. Temperature - a measure of the average kinetic energy of the particles in a substance.

2. Kinetic Energy - energy an object posses because of its motion. KE = 1/2 mv2 where m = mass and v = velocity

3. absolute zero - the temperature at which all molecular motion stops. Absolute Zero = -273 oC or 0 K

4. Converting from Celsius to Kelvin

• K = oC + 273

• 5. Energy always flows from an object of higher temperature to one of lower temperature until they both reach the same temperature.
6. Heat is the amount of energy transferred from a warmer object to a cooler object. Heat is measured in Joules.

• III. Distinguishing Properties of Liquids

A. Liquids have definite volume and definite shape.

B. Particles slide past one another.

C. Generally liquids are less dense than solids. (Solid water and Liquid water are exceptions)

D. Liquids are less compressible than gases.

E. Liquids are viscous.

1. Viscosity is the internal friction of a liquid. We also say that it is the liquid's resistance to flow.

2. High Molecular Weight - High Viscosity

3. Low Molecular Weight - Low Viscosity

• F. Surface Tension - contractive force along the surface of a liquid.

Example: This is why some insects can walk on water.

Example: Soap decreases surface tension.

G. Vapor Pressure - pressure exerted by the molecules of a confined vapor

H. Heat (Enthapy) of Vaporization: total heat or energy required to evaporate a liquid.

I. Normal Boiling Point: the temperature at which the vapor pressure is equal to the standard atmospheric pressure (101.325 kPa).

J. Difference between Boiling and Evaporation:

1. Evaporation: entirely a suface effect that can occur at any temperature (liquid to gas)

2. Boiling: bubbles form at the bottom of a liquid and rise to the top. (liquid to gas) It can only take place at certain temperatures and pressures.

K. Hydrogen Bonding in Water

1. Compounds containing hydrogen bonded to N, O, or F are very polar and form hydrogen bonds.

Hydrogen Bonds are not as strong as an actual chemical bond but it can hold the two molecules firmly together.

2. Ice is less dense than liquid water. This is because water expands when it freezes into ice. This occurs because hydrogen bonding pulls the molecule into an open crytalline structure that occupies more space than the liquid.

• IV. Distinguishing Properties of Solids

A. Solids have definite volume and definite shape.

B. Particles have little movement, but they do vibrate against one another.

C. Pure solids melt at definite temperatures.

D. When solids melt, a definte amount of heat is absorbed.

E. Melting Point: temperature at which a solid turns into a liquid.

F. Heat (Enthalpy) of Fusion: total heat or energy required to melt a substance.

G. All solids are made of crystals. Crystals have repeating, 3-D patterns.

H. Solids can form allotropes. Allotropes are two or more different molecular forms of the same elements.

Three Basic Assumptions of the Kinetic Theory?
Kinetic energy is the energy produced or exerted by an object in motion. This makes 3 basic assumptions. There is matter (the object exists), it is moving (in motion), and it is producing or exerting energy.

Gases : Graham's Laws of Diffusion and Effusion

• Only a few physical properties of gases depends on the identity of the gas.

• Diffusion - The rate at which two gases mix.

• Effusion - The rate at which a gas escapes through a pinhole into a vacuum.

Thomas Graham
Graham's Law of Diffusion

The rate at which gases diffuse is inversely proportional to the square root of their densities.

Since volumes of different gases contain the same number of particles (see Avogadro's Hypothesis), the number of moles per liter at a given T and P is constant. Therefore, the density of a gas is directly proportional to its molar mass (MM).

Graham's Law of Effusion
The rate of effusion of a gas is inversely proportional to the square root of either the density or the molar mass of the gas.

The time required for 25-mL samples of different gasses to diffuse through a pinhole into a vacuum.

The Kinetic Molecular Theory and Graham's Law

Since KEavg is dependent only upon T, two different gases at the same temperature must have the same KEavg

Simplify the equation by multiplying both sides by two:

Rearrange to give the following:

Take the square root of both sides to obtain the following relationship between the ratio of the velocities of the gases and the square root of the ratio of their molar masses:

This equation states that the velocity (rate) at which gas molecules move is inversely proportional to the square root of their molar masses.

Diffusion
Diffusion refers to the process by which molecules intermingle as a result of their kinetic energy of random motion. Consider two containers of gas A and B separated by a partition. The molecules of both gases are in constant motion and make numerous collisions with the partition. If the partition is removed as in the lower illustration, the gases will mix because of the random velocities of their molecules. In time a uniform mixture of A and B molecules will be produced in the container.

The tendency toward diffusion is very strong even at room temperature because of the high molecular velocities associated with thethermal energy of the particles.