Temperature--Volume Relatationship

Temperature-Volume Relationship

Purpose: In this lab we will study how temperature changes of a gas sample influence its volume.

Hypothesis: I think that as temperature increases the volume will increase as well.

Materials:

* Thermometer

* 2 rubber bands

* Capillary tube

* Ruler

* Hot plate

* Oil bath

Procedure:

1. Using two small rubber bands fasten a capillary tube to the lower end of a thermometer. Place the open end of the tub closest to the thermometer bulb and 5-7 mm from its tip.

2. Immerse the tube and thermometer in hot oil bath that that has been prepared by your teacher. Be sure the entire capillary tub is immersed in the oil. Wait for your tube and thermometer to reach the temperature of the oil (approximately 100oC) Record the temperature of the bath.

3. After you tube and thermometer have reached constant temperature, lift them until only about one quarter of the capillary tube (open end down) is still in the oil bath. Pause for about 3 sec. to allow some oil to rise into the tube. Then quickly place the tub and thermometer on a paper towel (to avoid dripping) and carry them back to your desk. CAUTION: Be careful not to touch the hot end of the thermometer or the drips of hot oil.

4. Lay the tube and thermometer on a clean piece of paper towel on the desk. Make a reference line on the paper at the sealed end of the capillary tube. Also mark the upper end of the oil plug. Alongside this mark write the temperature corresponding to that air-column length.

5. As the temperature of the gas sample drops, make at least six marks resenting the length of the air column trapped about the oil plug at various temperatures. Write the corresponding temperature next to each mark. Allow enough time so the temperature drops by 50-60oC

6. When the thermometer shows a steady temperature (near room temp.), make a final observation of length and temp. Discard the tube and the rubber bands according to you teacher's instructions. Wipe the thermometer clean.

7. Measure the length (in cm) from each marked line to the marked line to the mark for the sealed end of the tube. Record each length of the gas sample. Have your teacher check you data before you discard you paper towel.

8. Wash your hands thoroughly before leaving the laboratory.

Observations:

# Temperature(Ñ"F) CM from top

1 100Ñ" 8.9

2 80Ñ" 8.7

3 65Ñ" 7.7

4 50Ñ" 7.4

5 40Ñ" 7.2

6 25Ñ" 6.9

7 22Ñ" 6.7

Questions:

1. At what temperature does your extended graph line intersect the x-axis?

The temperature where the line intersects the x-axis is at approximately 205Ñ" Fahrenheit.

2. a. What would be the volume of your gas sample at that temperature?

There would be no volume of my gas sample at that temperature.

b. Why is that volume only theoretical?

The volume is only theoretical because you can't really measure the amount of gas inside the capillary tube.

3. Renumber the temperature scale on you graph, assigning the value zero to the temperature at which your plotted graph line intersects the x axis. The new scale expresses temperature in Kelvin (K)--the kelvin temperature scale. One Kelvin is the same size as on degree Celsius. However, unlike zero degrees Celsius, zero kelvins is the lowest temperature theoretically possible. It is called absolute zero.

4. Based on your graph, what temperature in Kelvin (K) would correspond to 0oC, the freezing pt. of water? What temperature would correspond to 100o, the normal boiling point of water?

Conclusion:

The

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