Chapter 8 Solids, Liquids, and Gases

States of Matter Four states of Matter: 1.Solids – do they move? Yes, they vibrate a.Kinetic Theory of Matter – particles are in constant motion in all states of matter. (they “vibrate”) In a solid, the particles vibrate & bump against each other, but they stay in position. Solids have a definite volume and a definite shape. b.In most solids, the particles are arranged in repeating geometric patterns forming crystals – ex: Salt: cubes, Snowflakes: hexagons, Quartz: rectangular boxes c.Amorphous solids – have no regular form; sometimes referred to or classified as thick or viscous liquids. Ex: Glass, Plastic, Some waxes

States of Matter - continued 2.Liquids – are fluids (they “flow”) and will take the shape of their containers; they can’t be squeezed into a smaller volume. They have a definite volume but no definite shape. According to the Kinetic Theory of Matter, particles in a liquid are also in constant motion, but in a liquid, particles can move out of position, change the shape. 3.Gases – expand and contract to fill their container (fluid) and they can be squeezed into a smaller volume: NO definite volume and NO definite shape. Vapors are gaseous substances that are normally solid or liquid at room temperature. 4.Plasma – particles are so hot and they move so fast that when they collide, they split into + and – charged particles. Ex: sun, stars, lightning, and gases inside fluorescent light bulbs.

Water – Most important liquid on Earth 1.Freshwater (What we use in our homes) makes up only ______% of the water on Earth. The average person uses _______ gallons of water per day: ~ _______ gal. for cooking, bathing, toilet, heating, & cooling, ~______ gal. to produce materials & electricity; ~ _______ gal. to water crops for food. See chart on page Polluted water – contains high levels of unwanted materials such as chemicals from _______________, from _____________, from ______________ & _________ wastes (sewage), hot water, and acid rain.

Changes in State 1.Evaporation – a change from a _________ to a ______, gradually and at a temperature lower than boiling point. 2.Sublimation – a change in state from a _______ to a ______ without forming a liquid. (ex: dry ice, freezer burn) 3.Condensation – a change from a ______ to a __________ (ex: when a glass “sweats”; rain) 4.Melting – change from a ________ to a _________ (ex: ice to water) 5.Freezing – a change from ________ to ________ (ex: snow, sleet, water to ____, lava to ________ _____ )

Changes in State 6.Heat of fusion – the energy needed to change from a ________ to ________. 7.Heat of vaporization – the energy needed to change from a ___________ to a ______. 8.Thermal Expansion – characteristic of matter that it will expand when ___________ and contract when ___________. EXCEPTION: ( ________ expands when solidified or frozen)

Behavior of Gases - Pressure Pressure – the amount of ________ exerted per unit of _____. –Formula: ___________ –Unit (SI): Pascal = 1 N/m 2 – which is very small so we use kPa (1000 Pascals) [the English unit is lb/in 2 ] –Atmospheric pressure – the pressure at ____ level = kPa: At Earth’s surface, the air/atmosphere exerts the pressure of 101,300 N on every square meter. [101,300N~weight of a large truck]. There is less pressure in the mountains, more pressure below sea level.

Behavior of Gases – Gas Laws Boyle’s Law – If volume decreases, pressure increases (temperature remains constant) OR if volume increases, pressure decreases. Volume and Pressure are inversely proportional (opposite) Boyle’s Law involves Volume and Pressure. Ex> squeezing a pillow decreases volume, increases pressure. Charles’ Law – If temperature increases, volume increases; if temperature decreases, volume decreases. (Proportional – increase or decrease together). –Ex> a balloon in the sun will expand; it will contract in a freezer. With the calculations of Charles’ Law, Absolute Zero has been determined to be 0º Kelvin which equals -273ºC or ºF. At this temp. all molecular motion stops.

Uses of Fluids ( Liquids, Gases, Plasma ) Archimedes Principle: the buoyant force on an object in a fluid is equal to the weight of the fluid displaced by the object. This principle allows objects to float. Why do they float? They have buoyancy – the ability of a fluid to exert an UPWARD force on an immersed object. less –If the buoyant force is less than the object’s weight, the object will sink. –If the buoyant force is greater than the object’s weight, the object will float.

Uses of Fluids ( Liquids, Gases, Plasma ) Pascal’s principle: pressure applied to a fluid is transmitted unchanged throughout the fluid. –Toothpaste tube –Squeezing a balloon –Hydraulic machines – p. 211 – two cylinders with pistons connected by a pipe; fluid in one piston is compressed and a forced into the other cylinder, pushing up on the other piston in the other cylinder, lifting an object.

Uses of Fluids ( Liquids, Gases, Plasma ) Bernoulli’s principle – as the velocity of a fluid increases, pressure decreases, so objects will “lift”. p This principle allows planes and birds to fly. Venturi effect: the speed of air increases as it is forced through smaller openings, decreasing the pressure.