Phase Changes Thursday, August 25th

Do Now: Describe this graph in words:

This Week: Take-Home Quiz—handed out on Friday, due next Monday! (You can get it early!) First Test—Next Tuesday! Extra Credit: For every ten minutes you study (shown via summary of video you watched), you earn one extra credit point. Up to 100 minutes of studying = 10 EC pts

Examine this Conclusion: Our results demonstrate the amount of energy required for water to transform states. We saw that the temperature remained constant as the ice was melting. However, once the ice was melted the temperature rose at an ever-increasing pace (2 degrees per 30 seconds, then 3, then 5, then 6) until the water was at a boil. The rate of temperature change was constantly increasing once the ice melted because before then it was being used to convert the solid ice to liquid. While the temperature was rising the energy then was being used to increase the motion of the water molecules so that they might escape the liquid phase, which explains why we saw bubbling before we saw a full boil. Once the water was boiling, we saw the temperature become constant once more because all the energy required to transform states had been acquired at 99 degrees Celsius. Thermal energy (or temperature) was being measured and from that we could identify that the most energy was added during the liquid phase in order to speed the molecules up enough to transform them into molecules of gas.

What is a Phase Change? Is a change from one state of matter (solid, liquid, gas) to another. Phase changes are physical changes because: - It only affects physical appearance, not chemical make-up. - Reversible

What happens during a phase change? During a phase change, heat energy is either absorbed or released. Heat energy is released as molecules slow down and move closer together. Heat energy is absorbed as molecules speed up and expand.

Types of Phase Changes Types of Phase Changes

Melting Phase change from a solid to a liquid Molecules speed up, move farther apart, and absorb heat energy

Freezing Phase Change from a liquid to a solid Molecule slow down, move closer together and release heat energy.

Vaporization (Boiling) Phase change from a liquid to gas. It occurs at the boiling point of matter. Molecules speed up, move farther apart, and absorb heat energy.

Evaporation Phase change from a liquid to a gas on the surface of a liquid (occurs at all temperatures). Molecules speed up, move farther apart, and absorb heat energy.

Condensation Phase change from a gas to a liquid. Molecule slow down, move closer together and release heat energy.

Sublimation Phase change from a solid to a gas. Molecules speed up, move farther apart, and absorb heat energy.

Deposition Phase change from a gas to a solid. Molecules slow down, move closer together and release heat energy.

Graphing a Phase Change

Melting & Boiling Points Melting Point: The temperature at which a solid changes into a liquid. Boiling Point: The temperature at which a liquid changes into a gas. What is a Freezing point? Compare the freezing and melting points of water.

Summary

Graphing a Phase Change Why is there no change in temperature during a phase change? Define melting and boiling points. What is the melting point and boiling point of water? At what temperature does water freeze and become a solid?

Let’s play Kahoot Review

Test Review Day No. 1 Friday, August 26, 2016

Do Now: Generate a list of all the topics we have studied thus far: Rank the topics from least comfortable ( ?) to most comfortable (  )

This Week: Take-Home Quiz—handed out Today, due next Monday! First Test—Next Tuesday! Extra Credit: For every ten minutes you study (shown via summary of video you watched/ content you reviewed), you earn one extra credit point. Up to 100 minutes of studying = 10 EC pts

Let’s Play Jeopardy: Choose teams (4 different teams), get a whiteboard, and a marker All have to take a turn writing, but you can get help from your team. If a team gives a wrong answer, then the others get a turn to correct it.

Study this weekend! We will have one more day of review on Monday! Be certain to study and create a list of questions to review for Monday!