CHEMISTRY 20 UNIT 2 GASES Properties PROPERTIES PATTERNS

CHEMISTRY 20 UNIT 2: GASES Properties

PROPERTIES & PATTERNS Recall what we know about gases already. � Solubility rules � Which elements are gases � Etc. The study of gases is unique � It requires the use of your imagination (more than usual!)

CHEMICAL PROPERTIES Gases can be very different from each other � They have diverse chemical properties The halogens (chlorine, flourine) and others (oxygen) are very reactive. Nitrogen is slightly reactive The noble gases are essentially inert (nonreactive)

PHYSICAL PROPERTIES Despite being so different chemically, gases have remarkably similar physical properties � Gases have neither shape nor volume of their own They always fill their containers � Gasses Volume becomes significantly smaller when pressure is applied � Gases are highly compressible diffuse They move spontaneously through available space � Temperature gas affects either the volume or the pressure of a

GAS: EMPIRICAL DEFINITION A gas is a substance that fills and assumes the shape of its container, diffuse rapidly, and mixes readily with other gases Gases increase in volume, pressure or both when heated and decrease in volume when pressure is applied

PRESSURE A force per unit area � Standard unit = kilopascal (k. Pa) � 1 k. Pa = 1000 N/m² � The force of 1000 N on an area of 1 m²

ATMOSPHERIC PRESSURE Pressure exerted on anything on earth by the weight of the air above us. � Measured by a barometer At sea level, average atmospheric pressure = 101 k. Pa Standard pressure = 101. 325 k. Pa – also called one standard atmosphere (1 atm)

STANDARD CONDITIONS STP (Standard Temperature and Pressure) � Traditional conditions for work with gases � 0 degrees Celsius, and 1 atm (101. 325 k. Pa) SATP (Standard Ambient Temperature and Pressure) � New set of conditions which simplify experimental set-up and calculations � 25 degrees Celsius and 100 k. Pa

ASSIGNMENT Reading � Nelson Pages 142 – 150 Questions � Graphic Organizer of gas properties & pressure units � Lab exercise 4 a page Nelson 148 (imaginary lab) � Do exploration Nelson page 147 if time