Name: ______________________________

QUESTION 1: CONVERSION FACTORS

PART A:

Usually when you want to convert a value measured in one set of units to another (e.g. temperature in °F to temperature in °C) you use conversion tables published in a book (e.g. Table at the end of this lab). In order for you to fully understand how such conversions are determined and to give you practice calculating a conversion factor, the first part of this lab is concerned with the relation of the two temperature scales °F (Fahrenheit) and °C (Celsius).

If you did not have a conversion factor between these two scales you could determine it by taking two thermometers, one measuring in °C the other in °F, and putting them next to each other in a range of environments and observing the temperatures on the two scales. This has been done for you, the data have been plotted and a best fit line drawn.

1. This graph can be used to determine the relation between the two temperature scales and thus to derive a conversion factor between °F and °C. Use equations 1.2 and 1.3 in the notes with Lab 1 to calculate the slope (m) and the intercept (b) for the linear relation you have graphed. Label the points you select for y₂, y₁, x₂ and x₁ on your graph and be very precise in your measurements. Show all your calculations. Write your final answer as an equation relating °F (Y) to °C (X).

y₂ _________________ y₁ _________________

x₂ _________________ x₁ _________________

m = _________________ b = _________________

Equation _______________________________________________

2. Using the equation you calculated complete the following table. You will be given a thermometer to make the readings in the classroom and outside. Note carefully what units your thermometer measures in (°F or °C) and then convert to the other set of units (°C or °F). Then convert your Celsius and/or Fahrenheit temperatures to Kelvin (see the conversion factors table at the end of this lab).

Remember to report your answers to the appropriate number of significant figures.
 

Temperature	°C	°F	°K
Highest temperature recorded in Indianapolis (July, 1934)	41.7°C
Lowest temperature recorded in Indianapolis (January 1994)	-32°C
Normal September temperature in Indianapolis	19°C
Air temperature in the classroom
Air temperature outside

PART B:

NOTE: Be careful about the number of decimals you should include in your final answers.

1. Convert 790 ft to m. This is the elevation of the weather station at Indianapolis Airport.
 
 
 

2. Convert 8,850 m to ft. Altitude of Mount Everest.
 
 
 
 

3. Convert 75 mph (or mih^-1) to ms^-1. Minimum wind speed in a hurricane.
 
 
 
 
 
 

QUESTION 2: THE GAS LAWS

The volume of different liquids and solids will vary according to the size and nature of their specific molecules. In a gas, the molecules are relatively far apart, and thus general laws can be stated about how environmental conditions affect gas volume.

CHARLES’ LAW: The volume of a gas is proportional to its temperature, as long as its pressure is constant. The gas gains volume as the temperature goes up, and the volume decreases as the temperature goes down.

BOYLE’S LAW: The pressure of a gas is inversely proportional to its volume, as long as its temperature is constant. As the pressure increases, the volume decreases, and as the pressure decreases, the volume increases.

IDEAL GAS LAW: A theoretical concept of a gas that would obey the gas laws exactly.

In this experiment you will explore the relationship between temperature and volume of a gas: Charles’ Law.

PART A: GATHERING DATA

    a) Measure the circumference of the balloon (the distance around it) using a piece of string. Using a marker pen, mark on the balloon

         where you took your measurements and make subsequent measurements (questions below) in the same place.

    b) Take the piece of string and measure it against a ruler.

    c) Measure the air temperature of the room. Record both the circumference and temperature measurements in the table below.

2. Place the balloon in the ice bath until you see a change in size (about 5 minutes). Then quickly measure the circumference of the balloon. Record the temperature of the ice water. Record the temperature and circumference of the balloon in the table below.

3. Next, place the balloon over boiling water. Hold the balloon in the steam until you notice a change in size and then carefully measure its circumference. Record this value and the temperature of the steam in the table below.

PART B: ANALYZING DATA

1. For each set of conditions:

    a) Calculate the volume of the balloon (m³). Make sure you state your answer in the correct units.

NOTE: Use your measurements in meters and the following equations to compute the volume.

Where, r = radius; C = circumference; V = volume; π = 3.14.

    b) Convert the temperature to degrees Kelvin (°K)
 
 

NOTE: Show all your work for at least one of the radius and volume calculations

2. Draw a graph of your results. Plot temperature as the independent variable. Select a range from 0 to 400 °K for temperature. The range for volume values should also start at zero.

3. Describe the relationship between temperature and volume of a gas, and name the law that is involved.
 
 
 
 

4. a) Draw a straight best-fit line on your graph. According to your graph, at what temperature does the volume of an ideal gas equal zero? What value should it be?

    b) What process are you using to give the answer to this question: interpolation or extrapolation? Why?
 
 
 
 
 
 
 

PART C: LATENT HEAT OF FUSION AND VAPORIZATION

The three phases of matter are solid, liquid, and gaseous. A phase change occurs when a substance changes from a solid to a liquid, or from a liquid to a gas. When a solid is heated to the melting point, or when a liquid is heated to the boiling point, heat energy (referred to as latent heat) is used to change the phase of the substance.

1. Record the temperature of a beaker of ice every 30 seconds as it is heated (put the hot plate setting around 5 or 6). Continue to take temperature readings every 30 seconds until the water has been boiling vigorously for 2 minutes. Note the times the ice melts and the water boils. Do not let the thermometer touch the bottom of the beaker.
 

Time	Temp	Time	Temp	Time	Temp	Time	Temp

 

PART D: ANALYSIS

1. a) Draw a line graph of your results, with temperature in °C on the vertical axis and time (minutes or seconds) on the horizontal.

    b) Label the following points/areas on your graph:

        Melting point (when ice starts to melt)

        Point where all ice melted (the content of the beaker is 100% liquid water)

        Boiling point
 
 

2. Examine the shape of the line on your graph. When the heat added to the water does not cause a rise in temperature, the line is horizontal.

Label this on your graph: No temperature change.
 
 

3. What was the heat being used for when you reached a plateau (flat line where temperature remains constant) like that?
 
 
 
 
 
 
 
 
 
 
 
 

4. What name is given to this type of energy exchange?
 
 

Units and Conversions

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