Measurement and Graphing
Chemistry
Name________________________block__date_______
Some of the most important activities in Chemistry involve making measurements, correctly reading
measurement tools and communicating the results of the data. Often, graphs are used to visually present this
information.
In this activity measurements will be made using Celsius and Fahrenheit thermometers of three
different temperature environments. Readings from the thermometers must be recorded to reflect the
precision of the instrument. Make sure to record your data to one estimated place. Data will be tabulated for
the entire class and then graphs of degrees Fahrenheit vs. degrees Celsius will be prepared in order to
determine a relationship between Celsius and Fahrenheit degree measurements.
CAUTION Thermometers are fragile and can easily break. Make sure you always have a hand on your
thermometer unless it is placed in a vessel where it cannot fall.
Procedure
1.
Record the current room temperature from each of your thermometers in the data table below.
2.
Place both thermometers either in the boiling water bath or the ice bath and leave them in place until
the temperature remains constant for at least 15 seconds. Record the temperatures.
3.
Place both thermometers into the third bath as in number 2, record the temperatures.
4.
Obtain the class data and record it in the data table in your notebook.
DATA TABLE (copy this data table into your lab notebook)
Group
Ice Water Temp
(°C/°F)
Room Temp
(°C/°F)
Boiling Water Temp
(°C/°F)
A
B
C
D
E
F
G
H
Graph
1.
Draw a rough graph in your laboratory notebook. You will be provided with a sheet of graph paper with
finer divisions to complete for the final lab report. Set up a graph to plot the Fahrenheit data vs. the
Celsius data. Usually the x-axis is used for the independent variable and the y-axis is used for the
dependent variable. In this lab both are dependent variables (the water baths are the independent
variables—the ones we chose to change) so we must choose and Celsius will be our independent
variable.
2.
Draw axes a few blocks from each edge. Make a scale for each axis that allows the graph to fill as much
of the graph paper as possible, but still allows a simple and sensible division such that each block
represents a simple integer number—1,2,5,or 10 are best. Label the axes, identifying the variable and
the units. Label the scale.
3.
Plot the data from each Group in a single color or with a single shape point. You will have three data
points from each Group.
4.
After plotting all of the data, draw the best straight line through the data that you can. The line should
represent the best average of the data.
5.
Determine the slope of this line including units. Choose two data points that are NOT data points. These
two points should be far apart on your straight line. Identify these two points by circling them on your
graph and writing their (x,y) coordinates right next to the point including units. Show the slope
calculation right on the graph, identifying the result, including units.
6.
Determine the equation for this line in y = mx + b format. Use the appropriate variables and the correct
slope, with units. Write this equation on the graph as well.
7.
Give your graph a descriptive title in the upper right corner of the page.
Analysis Questions
6.
1.
If the Celsius thermometer you used in your group recorded a temperature that was two
degrees higher than the actual temperature for every measurement, would this represent an
error in precision or in accuracy? Explain.
2.
If the same pair of thermometers was used to collect all of the data instead of a different pair of
thermometers for each group, would the resulting data be more precise or more accurate?
Explain.
3.
If your group moved the thermometer from the ice water bath to the hot water bath, but only
waited a minute to read the thermometer, would the recorded temperature be higher or lower
than the actual temperature of the water bath. Would this error make the calculated slope of
the line a larger value or a smaller value? Explain.
4.
If the ice melted over the course of the period and the water temperature rose between the
times that the first groups measured the temperature and the times that the last groups
measured the temperature, how would this affect the plotted data. How would this affect the
results in the calculated slope of the line? Explain.
Discussion – For this lab, the discussion should describe the results of this experiment (restate the
equation for the line obtained), explain what the line represents and include a description of how
accurate or how precise you think the results are. State at least two changes you could make in the
procedure of this lab to enable you to get better—more accurate, or more precise—results. Explain why
these changes would produce better results.