Solids, Liquids, and Gases Chapter Two Solids, Liquids, and Gases

Lesson 2-1- States of Matter Although there is an new state of matter – Plasma, for this chapter, we are going to talk about three states of matter Liquid Solid Gas

Solids A solid has a definite volume and a definite shape. The particles that make up a solid are tightly packed. Each particle is tightly fixed in one position – making them hard to move. Particles in a solid are not completely motionless, the particles vibrate.

Solid/Molecules

Solids In many solids, particles form a regular, repeating pattern. These patterns are called crystals. Solids that are made up of crystals are called crystalline solids – sugar and salt.

Solids Amphorous Solids, for example rubber and plastic, are not arranged in a sequenced pattern.

Liquids Liquid has no shape of its own. A liquid takes on the shape of its container. The particles in a liquid are packed almost as closely as in a solid, however, the particles have room to move freely. A liquid has definite volume.

Liquids Because the particles in a liquid are free to move, a liquid can flow from place to place. Some liquids flow more easily than others – the resistance of a liquid to flow is called viscosity. Liquids with high viscosity move slow, and liquids with low viscosity move fast.

Test Yourself Liquid Breakfast Orange Juice Maple Syrup Which has high viscosity? Which has low viscosity?

Test Yourself Orange Juice --- Low Viscosity Maple Syrup --- High Viscosity

Gases A gas does not have definite shape or definite volume. A gas can change volume very easily. The particles of a gas move at high speeds in all directions. Gas particles spread apart, filling all the space available to them.

SOLID LIQUID GAS

Lesson Two Gas Behavior

2-2 The volume of gas is the volume of its container. Temperature is a measure of the average energy of motion of particles of a substance. The faster the particles are moving, the greater their energy, and the higher the temperature.

2-2 Because gas particles are moving, they are constantly colliding with one another. They also bump along the walls of their container. As a result, the gas exerts an outward push on the walls of the container. Pressure of the gas is the force of its outward push divided by the area of the walls of the container.

2-2 Measuring Pressure Pressure is measured in units of kilopascals (kPa). Pressure = Force Area

2-2 Robert Boyle’s Law The relationship between the pressure and volume of a gas is named Boyle’s Law. When the pressure of a gas is increased at a constant temperature, the volume of the gas decreases. When the pressure is decreased, the volume increases.

Boyle’s Law Animation http://www.chem.iastate.edu/group/Greenbowe/sections/projectfolder/flashfiles/gaslaw/boyles_law_graph.html

Boyle’s Law http://www.grc.nasa.gov/WWW/K-12/airplane/aboyle.html

Boyle’s Law

The truck is empty and waiting at the loading dock: 2-2 Boyle’s Law Truck Tires The truck is empty and waiting at the loading dock: The truck is then loaded with a delivery of 20 refrigerators: (1) Is there more pressure on the tires with the loaded delivery compared to the empty truck? (2) Does the delivery increase the volume of air in the tires, or decrease the volume of air in the tires?

2-2 Charles’s Law The relationship between temperature and volume of gas is named Charles’s Law. Charles found that when the temperature of a gas is increased at constant pressure, its volume increases. When the temperature of a gas is decreased, its volume decreases.

Charles’ Law - Animation http://www.chem.iastate.edu/group/Greenbowe/sections/projectfolder/flashfiles/gaslaw/charles_law.html

2-2 Charles’s Law (1)You fill a helium balloon on a winter day – does the volume of the balloon expand or contract? (2) You fill a helium balloon on a summer day – does the volume of the balloon expand or contract?

2-2 Charles’s Law Winter Day – the cold temperatures help the balloon to expand. Summer Day: the hotter temperatures make the balloon contract.

2-2 Test Yourself Does air in a sealed balloon placed in the a freezer represent Boyle’s or Charles’s Law? Does a hippity-hop represent Boyle’s or Charles’s Law? Explain.

Lesson 2-4 Changes in State

2-4 Thermal Energy Every substance contains energy from the movement of its particles, called thermal energy. Thermal energy is transferred from one substance to another as heat. Thermal energy always flows from a warmer substance to a cooler substance. A substance changes state when its thermal energy increases or decreases by a sufficient amount.

2-4 Melting The change in state from a solid to a liquid. Solid (Snow) Snow melts Into a puddle

2-4 Freezing The change of state from liquid to solid – the reverse of melting. You fill an ice-cube tray with water. You put the tray into the freezer and wait two hours. The tray is filled with ice cubes.

2-4 Vaporization Vaporization occurs when a liquid gains enough energy to become a gas. Liquid to Gas – Boiling Point. A pot of boiling water left on the stove will cause the liquid to vaporize into steam until the water is gone.

2-4 Evaporation Some confuse evaporation and vaporization. Evaporation occurs below a liquids boiling point - occurring on a liquids surface. Vaporization occurs when a liquid reaches its boiling point. The rain causes puddles to occur. The sun comes out and the puddles soon evaporate into the clouds, and the cycle begins again.

2-4 Condensation The opposite of vaporization. Condensation occurs when a gas loses enough thermal energy to become a liquid. On hot summer day, you set your glass of lemonade on the porch. Before you know it, your glass is sweating beads of water droplets. Condensation.

Condensation

2-4 Sublimation Sublimation occurs when the surface particles of a solid gain enough energy to become a gas. In sublimation, particles do not pass through the liquid state.

Sublimation Evaporation is not quite the correct term to describe what happens to a comet as it approaches the sun. The correct term is sublimation. The term describes what happens when a frozen material changes to gaseous form. (Evaporation describes what happens when a liquid changes to a vapor). The most common example of sublimation is that of dry ice, which is the common name of frozen CO2. When dry ice is exposed to the air it begins to sublimate, or change to vapor, before your very eyes. This happens to dry ice because at room temperature the frozen gas would rather be a gas than frozen solid.

When a comet approaches the sun, the comet comes to a region of space where it is warm enough that the frozen gases inside the nucleus would rather be gaseous than frozen solid, and that is when the tail and coma of the comet form.