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Phase Change

Page history last edited by Anna 16 years ago

Molecules and Phase Change Lab

Testable Questions:

What happens to the temperature when an object goes through a phase change?
What happens to the movement of the molecules as the object changes from solid, to liquid, and finally to gas?

Definition (Insert these into your Wiki):

Molecule: the smallest physical unit of an element or compound, consisting of one or more like atoms in an element and two or more different atoms in a compound.
Solid: having three dimensions
Liquid:composed of molecules that move freely among themselves but do not tend to separate like those of gases
Gas:a substance possessing perfect molecular mobility and the property of indefinite expansion, as opposed to a solid or liquid.
Phase Change:a change from one state (solid or liquid or gas) to another without a change in chemical composition

Notes that need to be included in your Wiki before doing the experiment: (Use pages 60 – 63 in your book)

1. What are the two types of solids? Describe each type and insert an image of each.

a.Chocolate

b. A bat

The image “http://www.chocolate-world.net/images/Chocolate.png” cannot be displayed, because it contains errors.

The image “http://www.athleticpets.com/images/Chicago_Cubs_Plush_Bat.jpg” cannot be displayed, because it contains errors.

2. Movement of molecules:

State of Matter	How do the Molecules Move?
Solid	they cant move fast enough to overcome the strong attraction.
Liquid	more fast enough to overcome some of the attraction.
Gas	move fast enough to overcome nearly all of the attraction between them.

3. Insert a picture of what the water molecules look like as a solid, liquid, and gas in your Wiki. You will have to get these pictures from the web.

Solid	Liquid	Gas

4. Shape and Volume:

State of Matter	Can it change its shape?	Can it change its volume?
Solid	No	Yes
Liquid	Yes	No
Gas	Yes	Yes

Materials:

250 ml beaker
Thermometer
Ice
Hot Plate
Ring stand with clamps
Stopwatch

Procedures:

Using the 250 ml beaker, get about 125 ml of ice from the cooler
Set up the equipment as shown in the picture: Make sure the thermometer bulb stays completely surrounded by ice. Do not let the thermometer bulb touch any part of the beaker!

Let the thermometer sit in the ice for one minute and then measure the temperature of the ice. Record this temperature in the first row of your data table (Time = 0)
Turn on the hot plate to a strength of 5 or 300 degrees.
Timekeeper: immediately note the time on the clock. Take the temperature every minute and record it in the data table.
You will also need to write down your observation of what is happening. This is very important! For example: “All the ice has melted and is now water.”
As the ice melts, use the plastic spoon to stir to keep the thermometer bulb surrounded by ice.
Continue this process until the water has been boiling for 4 to 5 minutes. This will take about 30 minutes.
When finished, turn off the hot plate and call Mr. Ozeni over to your station so that he can take the beaker off the hot plate for you. DO NOT ATTEMPT TO REMOVE THE BEAKER YOURSELF!!

Data Table/Results:

Time (minutes)	Temperature (C)	Observations
0
1	1.5	The ice is starting to heat up.
2	5	The ice starts melting and it gets hotter.
3	9.5	The ice is starting to melt.
4	12	There is barely anymore ice.
5	17	The ice is just water.
6	32	It looks like there was never ice in it.
7	38	The ice is starting to just turn into straight water.
8	45	Now that its straight water, the water is heating up.
9	50	It starts getting hotter and bubbly.
10	58	The water starts bubbling up and almost boiling.
11	64	The water is heating up and boiling more.
12	70	the water is offically boiling at this very moment.
13	77	the water is still boiling.
14	83	the water is starting to steam.
15	90	The water is boiling at a high temperature.
16	95	The water is really hot and boiling.
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31

You will now need to create a temperature vs. time graph using excel (XY scatter)

Insert the Temperature vs. Time graph into the Wiki.

Data Analysis:

Graph analysis: Using your observations from the data table, you will be circling sections on the graph.
- Circle the section on the graph where the ice is melting to become a liquid.(make this a blue colored circle) and label it “phase change”
- Circle the section on the graph where the water is boiling to become a gas. (make this a blue colored circle) and label it “phase change”

What do you notice about the sections on the graph where the object is going through a phase change? Why do you think it happened that way?

3. Find a video of water molecules, starting off as ice, melting to become water, and then boiling to become gas. Then link it, or embed it into your Wiki.

Conclusion:

1. What happens to the temperature when an object goes through a phase change?

2. What happens to the movement of the molecules as the object changes from solid, to liquid, and finally to gas?

Related Links: