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Change and Heating/Cooling Curves POGIL

OBJECTIVES: ​ ● Be able to identify the state of based on the arrangement and behavior of the molecules in a model of matter. ● Predict phases of matter by location on a heating/cooling curve graph ● Create a cooling curve when given data and identify phase changes.

MODEL 1: PHASE CHANGE PARTICLE DIAGRAM The diagrams below represent molecules in the three phases of matter. Arrows in the diagram indicate matter undergoing a phase change. Kinetic theory states that all atoms in matter are in constant motion. The amount of motion depends on the amount of thermal energy (heat) contained in the matter. Matter changes phase from a to a when the amount of thermal energy increases to the point where molecules are moving fast enough to break the forces holding the molecules of a solid together. Likewise, water condenses when the temperature of a decreases to the point where gas molecules slow down enough that the intermolecular forces can hold the molecules together again.

Word Bank for Model 1:

Gas /Fusion Solid Liquid

DESCRIBE THE PARTICLE DIAGRAM WHAT PHASE IS THIS? ​ ​ A Answer: Answer:Solid

B Answer: Answer:Liquid

C Answer: Answer:Gas

1. LABEL the arrows in the diagram above, use the word bank to assist you. E = Answer: D = Answer: ​ ​ F = Answer: G = Answer: ​ ​

2. What is changing between the diagrams if you are moving from left to right? Answer:

3. If you could look at these particles in real time, what would they be doing? How would it differ ​ ​ between the 3 different diagrams? Answer: MODEL 2: HEATING CURVE GRAPH The following graph shows what happens to water as it goes from ice to liquid water to water . ​ ​ At sea level water freezes/begins to melt at 0˚C, boils/begins to turn to steam at 100˚C. Use the words from the chart in model 1 and the heating curve graph on the next page to identify these phases and phase changes.

First, let’s label the pieces of the graph (A, C, E, and F are just there for the line segment names) B = Answer: 1. = Answer: x-axis = Answer: ​ ​ ​ D = Answer: 2. = Answer: y-axis = Answer: ​ ​ ​ 3. = Answer: ​

1. During which line segments does temperature increase? (AB, BC, CD, DE, EF - more than one is ​ ​ possible) Answer: ​ 2. During which line segments is there no change in temperature? Answer: ​ ​ ​ 3. At what temperature would segment BC occur? Answer: ​ 4. At what temperature would segment DE occur? Answer: ​

READ THIS: Kinetic energy is the energy of molecular motion in the form of heat. We measure Kinetic energy in degrees Celsius and it is represented as temperature.

5. Which line segment(s) show an increase in kinetic energy? Answer: 6. Compare the length of segments BC and DE. ​ ​ Answer: a. Provide an explanation for your observation that segment DE is longer than BC? Answer: MODEL 3: Heating curves for 4 different substances. READ THIS: and point are physical properties of matter and very depending on the substance. Below are 4 heating curves for 4 different substances. Use the graphs to answer the questions below.

1. Which substance has the highest ? Answer: ​ a. What is that boiling point of this substance? Answer: ​ 2. At what temperature range is NaCl a solid? Answer: ​

3. What is the melting point for Cl2? Answer: ​ ​ ​ 4. Which substance is a liquid at room temperature (25-27 ˚C)? Answer: ​

5. What phase is Cl2 in at room temperature? Answer: ​ ​ ​ 6. What is NaCl’s boiling point? Answer: ​

7. What temperature is Cl2 at after being heated for 20 minutes? Answer: ​ ​ ​

MODEL 4: MYO Cooling curve A cooling curve is simply the opposite of a heating curve, instead of temperature INCREASING, it is ​ ​ DECREASING (it will start high and go low). Use the information below to create this Cooling Curve for the unknown substance. - A sample of a substance is cooled from a temperature of 250°C to 10°C over a period of two hours. - The boiling point of the substance is 175°C and the melting point is 22°C. You may draw this on real paper, take a photo and upload into this document. It is okay if you don’t have graph paper, do your best!

Time (min) Temp (°C)

0 250

30 175

60 175

90 22

100 22

120 10

Label the following items in the appropriate locations:

Solid Liquid Gas Condensation Boiling Freezing Point Melting Point Fusion KE changing KE not changing