INTRO-GASES.pptx reviewer for 4th quarte

This is a reviewer for future purpose

1. UNIT IV MATTER AND ITS INTERACTIONS

2. RECAP… In your grade 8 chemistry, you learned different properties of Gases. Identify whether the statement is TRUE or FALSE. Gases have indefinite shape and volume. Gas is the state in which matter expands to occupy the volume and shape of its container. Gases have low density which contain scattered molecules that are dispersed across a given volume. Particles of gases move in random motion with little attraction to each other. Gases are highly compressible.

3. MODULE I : BEHAVIOUR OF GASES

4. Scientists have observed some activities involving gases. They found out that the behavior of gases is determined by the behavior of its individual particle. In 1870, scientists formulated the Kinetic Molecular Theory (KMT) using a simple model of an ideal gas or a theoretical gas. The particles of an ideal gas behave consistently and in a predictable manner.

5. PROPERTIES/NATURE OF GASES

6. PRESSURE The pressure of a confined gas is the average effect of the forces of the colliding molecules. It can be measured in atmosphere ( atm ), torr , psi, cmHg , mmHg) P = F/A where: P=pressure, F=force, A= area When you open a can or bottle of softdrinks , it fizzes because of the escaping dissolved carbon dioxide due to change of pressure. When the wind blows, it exerts pressure too

7. MASS The amount of gas or its mass could be expressed in moles or grams. The mass is negligible. Which is heavier, inflated balloon or deflated balloon?

8. VOLUME The volume of gas is the amount of space occupied by the gases. Gases have the tendency to occupy all the spaces of the container that they are confined. Gases have weak intermolecular forces of attraction, hence, they are arranged as far away as possible from each other. The common units used in expressing the volume of gas are liter (L) and milliliter (mL). The basketball is filled with air. So, it bounces while you are dribbling it.

9. TEMPERATURE The temperature of a gas is the measure of the hotness or coldness of an object. It is proportional to the average kinetic energy of its molecules. It can be measured in Celsius and Kelvin. Kelvin is the absolute scale

10. UNITS BEING USED TO EXPRESS THE PROPERTIES OF GASES VARIABLE UNIT Volume Cubic meter (m 3 ) Cubic decimeter (dm 3 ) Cubic centimeter (cm 3 ) Liter (L) Milliliter (mL) Quart ( qt ) Gallon (gal) Pressure Pascal (Pa), kPa Atmosphere ( atm ) Millimeters of mercury (mmHg) Centimeters of mercury ( cmHg ) Torr Lb /in 2 (psi) Temperature Celcius (⁰C) Farenheight (⁰F) Kelvin (K)

11. EQUIVALENTS Volume units and their equivalents 1 mL = 1 cm 3 1 L = 1 dm 3 1 m 3 = 1000 L Pressure units and their equivalents 1 atm = 760 mmHg = 76 cmHg = 760 torr = 101325Pa = 101.325kPa=14.6956 psi Temperature units and their equivalents 0 ⁰C = 273.15 K 0 ⁰C = 32 ⁰F

12. RELATIONSHIPS Directly proportional Indirectly proportional

13. GAS LAWS GAS LAW SCIENTIST FORMULA CONSTANT RELATIONSHIP BOYLE’S LAW Robert Boyle P 1 V 1 = P 2 V 2 Temperature Inversely proportional CHARLES’LAW Jacques Charles V 1 T 2 = V 2 T 1 Pressure Directly proportional GAY -LUSSAC’S LAW Joseph Loius Gay-Lussac P 1 T 2 = P 2 T 1 Volume Directly proportional COMBINED GAS LAW V 1 P 1 T 2 = V 2 P 2 T 1 AVOGADRO’S LAW Lorenzo Romano Amedeo Carlo Avogadro V 1 n 2 = V 2 n 1 Pressure, Temperature Directly proportional IDEAL GAS LAW PV = nRT

14. WHERE: V = Volume T = Temperature n = amount of gas in moles R = Universal gas constant 1 = Used as subscript, means initial condition 2 = used as subscript, means final condition