Presentation on theme: "Gases. Gases are All Around Us FormulaNameCharacteristics HCNHydrogen cyanideVery toxic, odor of almonds H2SH2SHydrogen sulfideVery toxic, odor of rotten."— Presentation transcript:
Gases are All Around Us
FormulaNameCharacteristics HCNHydrogen cyanideVery toxic, odor of almonds H2SH2SHydrogen sulfideVery toxic, odor of rotten eggs COCarbon monoxideToxic, colorless, odorless CO 2 Carbon dioxidecolorless, odorless CH 4 Methanecolorless, odorless, flammable C2H4C2H4 EthyleneColorless, ripens fruit C3H8C3H8 PropaneColorless, bottled gas N2ON2ONitrous DioxideColorless, laughing gas NO 2 Nitrogen dioxideToxic, red-brown, irritating NH 3 AmmoniaColorless, pungent odor SO 2 Sulfur dioxideColorless, irritating odor CH 3 SHMercaptanColorless, flammable
Gases are the Most Easily Understood Form of Matter Atoms Matter Three states of matter – solid, liquid, gas Solid LiquidGas
Gases - the Easily Understood Form of Matter Individual molecules of gases are far apart. Gas molecules (in the air) occupy 0.1% of the total volume. (In a liquid molecules take up 70% of space) The distance between molecules is 10 times more than the size of a molecule. Each molecule of a gas behaves as the other molecules weren’t present
Gases - the Easily Understood Form of Matter Gases may have different chemical properties, but the same physical properties. (Example: Air is a mixture of gases (N 2, O 2, others) that have different chemical properties but behave as one homogeneous mixture). Gases are composed of nonmetallic elements. They have simple molecular formulas. They have low molar masses. Gases expand to fill its container. (The volume of a gas = The volume of container in which gas is held) Gases are highly compressible. Gases form homogeneous mixtures. (Example: water and gasoline – liquids are not miscible but vapors form a homogeneous mixture.
Properties of Gases Pressure, P Volume, V Temperature, T
The Concept of Pressure Pressure is a force per unit area. P =F(N)/A(m 2 ) F- the force A – given area
Barometric Pressure The device to measure the pressure exerted by the atmosphere - a barometer. 1 atm = 760 mm Hg = 760 torr = × 10 5 Pa = kPa
Manometers The device to measure the pressure of a gas- a manometer.