Standard+3e

ACTIVITY: 1) Go to the website: http://phet.colorado.edu/simulations/sims.php?sim=States_of_Matter Go between solid, liquid, and gas. What do you have to do to go from a solid to a liquid? to a gas? what about returning?  2) http://www.colorado.edu/UCB/AcademicAffairs/ArtsSciences/physics/PhysicsInitiative/Physics2000/bec/temperature.html 3) Read the information below and answer the questions in your journal. 4) TAKE QUIZ HERE: https://www.quizlab.com/secured/authenticate_limited.cfm Click on "single class login", and input classword (tewinkle(#ofclass): ex. if you are in period 2, your classword is tewinkle2, Your password is first letter of name and as much of last name as fits (ex: htangen).   **Phase Transitions **  The transformation of one state of matter into another state is called a phase transition. The more common phase transitions even have names; for example, the terms melting and freezing describe phase transitions between the solid and liquid state, and the terms evaporation and condensation describe transitions between the liquid and gas state. When a solid is raised above the melting temperature, the atoms or molecules have enough energy to slide past one another so that the material-- now a liquid-- can flow. The density of the liquid stays similar to that of a solid because the atoms stay at about the same average distance. As thermal energy (heat) continues to increase, individual molecules may acquire enough energy to pull away from its neighbors and escape to become a molecule of gas. Gas molecules move about freely and collide randomly with the walls of a container and with each other. The distance between molecules in a gas is much larger than in a solid or a liquid, so the gas has a much different density than solids and liquids. Phase transitions occur at very precise points, **when the energy (measured as temperature) of a substance in a given state exceeds that allowed in the state.** For example, liquid water can exist at a range of temperatures. Cold drinking water may be around 4ºC. Hot shower water has more energy and thus may be around 40ºC. However, at 100°C under normal conditions, water will begin to undergo a phase transition into the gas phase. At this point, **energy introduced into the liquid will not go into increasing the temperature; it will be used to send molecules of water into the gas state.** Thus, no matter how high the flame is on the stove, a pot of boiling water will remain at 100ºC until all of the water has undergone transition to the gas phase. The excess energy introduced by a high flame will accelerate the liquid-to-gas transition; it will not change the temperature. The point at which a liquid turns to gas (boils) is called the boiling point. In water, the boiling point is 100 degrees. The point at which a solid turns to liquid (melting) is called the melting point. The melting point of water (ice) is 0 degrees. Every substance has a unique melting point and boiling point, which can be used to help identify that substance.  Phase transitions are an important part of the world around us. For example, the energy withdrawn when perspiration evaporates from the surface of your skin allows your body to correctly regulate its temperature during hot days. Phase transitions play an important part in geology, influencing mineral formation and possibly even earthquakes. And who can ignore the phase transition that occurs at about -3ºC, when cream, perhaps with a few strawberries or chocolate chunks, begins to form solid ice cream. Questions (not necessarily in order in the reading) **Q1: ** What is the hottest temperature liquid water can exist at? **Q3:** How do gas molecules travel through the air?
 * //Students know//** **//that in solids the atoms are closely locked in position and can only vibrate; in liquids the atoms and molecules are more loosely connected and can collide with and move past one another; and in gases the atoms and molecules are free to move indepen//** **//dently, colliding frequently.//** (Q. 3, 5, 6, 16, 19)
 * Q2: ** Why does the temperature remain constant as a substance changes from one phase to the next?
 * Q4:** Explain what is happening to the atoms in a solid, liquid, and gas.