PRESENTATION ON CHEMISTRY THREE STATES OF MATTER BY MRS. IRUM KHALID LECTURER DA SKBZ COLLEG E

1. PRESENTATIONONCHEMISTRYTHREE STATES OF MATTERBYMRS. IRUM KHALIDLECTURERDA SKBZ COLLEGE

2. ChemistryThe Three States of MatterGasLiquidSolid

3. Matter is anything that has mass and takes up space.

4. The Three States of MatterBasis of Classification Based upon particle arrangementBased upon energy of particlesBased upon distance between particles

5. States of Matter • Solids • A solid is matter that has that has definite size and shape. • Particle Movement Examples

6. States of Matter • Solids • Particles of solids are tightly packed, vibrating about a fixed position. • Solids have a definite shape and a definite volume. • Solids have an infinite number of free surfaces.

7. States of Matter • Liquids • Particles of liquids are tightly packed, but are far enough apart to slide over one another. • Liquids have an indefinite shape and a definite volume. • Liquids have one free surface.

8. States of Matter • Liquids A liquid takes the shape of any container.Example: Pour juice into a glass. • Particle Movement Examples

9. States of Matter • Gases • Particles of gases are very far apart and move freely. • Gases have an indefinite shape and an indefinite volume. • Gases have no free surfaces.

10. States of Matter • Gases Gas is matter that has no definite shape. Gases take the shape of whatever container they are in.Example: The air all around us is a gas Particle Movement Examples

11. States of Matter Microscopic Explanation for Properties of Solids • Solids have a definite shape and a definite volume because the particles are locked into place • Solids are not easily compressible because there is little free space between particles • Solids do not flow easily because the particles cannot move/slide past one another

12. States of Matter Microscopic Explanation for Properties of Liquids • Liquids have an indefinite shape because the particles can slide past one another. • Liquids are not easily compressible and have a definite volume because there is little free space between particles. • Liquids flow easily because the particles can move/slide past one another.

13. States of Matter Microscopic Explanation for Properties of Gases • Gases have an indefinite shape and an indefinite volume because the particles can move past one another. • Gases are easily compressible because there is a great deal of free space between particles. • Gases flow very easily because the particles randomly move past one another.

14. Kinetic Molecular Theory The Kinetic Molecular Theory explains the forces between molecules and the energy that they possess. This theory has 3 basic assumptions. 1.Matter is composed of small particles (molecules). The measure of space that the molecules occupy (volume) is derived from the space in between the molecules and not the space the molecules contain themselves. 2.When the molecules collide with each other, or with the walls of a container, there is no loss of energy. 3.The molecules are in constant motion. This motion is different for the 3 states of matter.

15. Kinetic Molecular Theory • Solid - Molecules are held close to each other by their attractions of charge. They will bend and/or vibrate, but will stay in close proximity. • Liquid - Molecules will flow or glide over one another, but stay toward the bottom of the container. Motion is a bit more random than that of a solid. • Gas - Molecules are in continual straightline motion. The kinetic energy of the molecule is greater than the attractive force between them, thus they are much farther apart and move freely of each other.

16. Kinetic theory Postulates 1.The gas consists of very small particles, all with non-zero mass. 2.These molecules are in constant, random motion. The rapidly moving particles constantly collide with the walls of the container. 3.The collisions of gas particles with the walls of the container holding them are perfectly elastic. 4.Except during collisions, the interactions among molecules are negligible (they exert no forces on one another). 5.The total volume of the individual gas molecules added up is negligible compared to the volume of the container. This is equivalent to stating that the average distance separating the gas particles is large compared to their size. 6.The molecules are perfectly spherical in shape, and elastic in nature. 7.The average kinetic energy of the gas particles depends only on the temperature of the system.

17. How the Kinetic Molecular Theory Explains the Gas Laws The kinetic molecular theory can be used to explain each of the experimentally determined gas laws. Boyle’s Law Charles’ Law Avogadro’s Law Graham’s Law

18. Boyle’s Law: • Boyle’s Law states that, at constant number of moles and temperature, pressure and volume are inversely proportional. “Constant number of moles” implies that the number of gas particles remains the same. “Constant temperature” implies that the average speed of the particles remains the same If the pressure and volume are inversely proportional, an increase in volume will lead to a decrease in pressure.

19. Charles’ Law • Charles’ Law states that, at constant number of moles and pressure, the volume and the temperature are directly proportional. “Constant number of moles” implies that means that the number of gas particles remains the same. “Constant pressure” implies that the rate at which the particles collide with the wall of the container remains the same. If volume and temperature are directly proportional, an increase in temperature will lead to an increase in volume.

20. Avogadro’s Law: • Avogadro’s Law states that at constant temperature and pressure, the number of moles of gas and the volume are directly proportional. “Constant temperature” means that the average speed stays the same. “Constant pressure” means that the rate at which the particles strike the wall stays the same. If the number of moles and the volume are directly proportional, an increase in the number of moles will lead to an increase in the volume.

21. The Combined Gas Law and Ideal Gas Law: • The combined gas law is a statement of the relationships among pressure, volume and temperature at constant amount of gas. • The ideal gas law is a statement of the relationships among pressure, volume, amount of gas, and temperature for a gas at a set condition. These variables are inter-related as collisions, speed and distance. • If a gas obeys the assumptions of kinetic molecular theory, it must be “ideal.”

22. Graham’s Law • Graham’s Law of diffusion states that the rate at which a gas diffuses is inversely proportional to the square root of its molar mass. Graham found that the rates at which gases diffuse is inversely proportional to the square root of their densities. This relationship eventually became known as Graham's law of diffusion. In other words, the smaller the gas particle the faster it effuses.

23. DALTONS LAW It states: The total pressure exerted by gases is equal to the sum of the partial pressure of each individual component in a gas mixture.

24. Changes in State (phase changes) 1. Melting - solid to liquid a. Particles get more kinetic energy and begin rotating around each other. b. There isn’t enough energy to break the inter-particular attractions, so the particles c. The energy required to melt a solid is called the heat of fusion. remain close (liquid).

25. Freezing - liquid to solid a. Particles lose kinetic energy and slow down. b. Attractive forces between particles become stronger than the particles’ motion, so the particles begin merely vibrating in place. c. The amount of heat the particles must lose to turn into a solid is called the heat of fusion.

26. Vaporization - liquid to gas a. Types: 1) Boiling - rapid; gas bubbles are produced throughout. 2) Evaporation - slow; occurs at the surface. b. Liquid particles gain enough kinetic energy to overcome forces between the particles and they begin translational motion; this energy is called the heat of vaporization.

27. Evaporation is a cooling process. a. Particles in a liquid gain kinetic energy. b. They leave as gas particles (taking the energy away with them). c. This leaves less energy in the liquid, therefore cooling down what is left.

28. Condensation - gas to liquid a. Particles lose kinetic energy, slow down, and come closer. Inter-particular forces become strong enough to make particles merely rotate around each other. c. The energy they lose to turn into a liquid is the heat of vaporization.

29. Sublimation - solid to gas or gas to solid a. Dry ice - carbon dioxide b. Iodine c. Frost 7. During phase changes there is no change of temperature.