PRE- LAB QUESTIONS: PHYSICAL CHANGES

NAME: ______DATE: ______

  1. What does not change during a physical change?
  1. List at least nine physical changes?
  1. What is measured at time zero?
  1. How many milliliters of water should be added to the beaker?
  1. According to the data table, how often will the temperature be recorded?
  1. When does recording the temperature of the water end?
  1. After looking further through the lab, what will be done with this data once it has been collected?

INTRODUCTION:

Physical changes occur when objects undergo a change that does not change their chemical nature. A physical change involves a change in physical properties. Physical properties can be observed without changing the type of matter. Examples of physical properties include texture, shape, size, color, odor, volume, mass, weight, and density. An example of a physical change occurs when making a baseball bat. Wood is carefully crafted into a shape, which allow a batter to best apply force on the ball. Even though the wood has changed shape the chemical nature of the wood has not been altered. The bat and the original piece of wood are still the same chemical substance. Boiling is also a physical change. It is when the vapor pressure of a liquid is the same as the atmospheric pressure. Boiling point a physical property is a temperature at which a liquid is evaporating and condensing at the same rate (at a certain atmospheric pressure). It is an intensive property (which means it is quantity independent). It is your mission in this activity to determine the boiling point of water.

PURPOSE: CHOOSE BY CIRCLING THE MOST APPROPRIATE ANSWER.

(a.)To determine the boiling point of a liquid water.

(b.) To determine if boiling is a physical property.

(c.)To determine the melting point of ice

HYPOTHESIS: CHOOSE BY CIRCLING THE MOST APPROPRIATE ANSWER.

(a.)If water is heated for 15 minutes on a hot plate, then it will continue to rise for all fifteen minutes, because heat is continually added to the water.

(b.)If water is heated for 15 minutes on a hot plate, then it will reach a maximum temperature and remain at this temperature as long as water remains in the beaker and the heat setting stays the same because boiling occurs at a specific temperature and atmospheric pressure.

PROCEDURE:

  1. Make sure your Lab Quest power pack is plugged in at

the lab table and the button in the upper left of the Lab

Quest has a blue light shinning around it. See diagram.

  1. The Mode Box should be selected for Time Based.

If not use the little blue stick and tap mode and change

it to time based. See diagram.

  1. The Rate should be set at 2.0 samples/min.

If not change it with the little blue stick by

tapping the rate box. See diagram.

  1. The Length of the experiment should be 15 minutes.

If not tap length and change it. See diagram.

  1. Place 100 mL of water from the tap into a 250mL beaker and place it on your hot plate.
  2. Place the temperature probe into a utility clamp attached to a ring stand.
  3. Lower the temperature probe into the beaker of water so that the tip of the probe is mid-way into the water.
  4. Turn on your hot plate to the maximum setting.
  5. Press the little key in the lower left of your screen. See diagram.
  1. Allow the program to run and while you are waiting label and title the graph attached to your lab. Finish your pre-lab questions and other text work.
  2. When the program stops you will see a small red box in the lower left hand corner of the Lab Quest screen. Tap it. See diagram.
  3. Click the data table in the upper right hand corner and record the data on your lab

sheet.

After you tap the data table you will see the following screen. Begin to copy this data

down onto the data table provided. You may also wish to ask your teacher how to download this data and print it on the computers in your room using the Logger Pro Program.

13. Tap the graph icon in the upper right hand corner of the screen and begin completing your graph on the graph paper provided. For extra credit you must obtain a USB cord for the teacher and download your data to logger pro on a computer in the room. Ask your instructor for instructions.

This is what the screen will look like when the graph icon is tapped

ASSIGNMENT:

  1. Fill in the data table or print from logger pro.
  2. Make a hand- made graph or use logger pro. The x axis is time (minutes) and the y axis is temperature (oC).
  3. Write a summary about this lab, which includes the following:
  4. Purpose (rewrite the purpose(s) that you chose at the beginning of the lab).
  5. Hypothesis (rewrite the hypothesis that you chose at the beginning of the lab).
  6. Write a summary about the lab and include the following words:
  7. Physical change
  8. Physical property
  9. Boiling point
  10. Intensive property
  11. Evaporation
  12. Liquid
  13. Gas
  14. Temperature
  15. Kinetic energy
  16. Heat
  17. Answer conclusion questions

CONCLUSION QUESTIONS: AFTER CONSTRUCTING THE GRAPH ANSWER THE FOLLOWING QUESTIONS.

  1. Did you choose the correct hypothesis?
  1. At what time did the temperature of the water stay constant?
  1. What do chemists call this temperature?
  1. What is happening to the kinetic energy of the water molecules during this time?
  1. What would happen to the plateau of this graph (the flat portion) if there were more than 100 mL of water in the beaker?
  1. What was the temperature change in the first three minutes of this activity?
  1. What do you think the graph would look like if there were another liquid (with a higher boiling point) mixed in with the water? Draw the general shape.

TIME ( ) / TEMPERATURE ( )