chemistry
Lina Gurung
3 days ago
1
files (1)GraphingData.docx
GraphingData.docx
LAB : GRAPHING DATA
In the chemistry laboratory the line graph is the most common graph. The line graph has a horizontal x-axis, or abscissa, and a vertical y-axis, or ordinate. The scale and units on each axis represents the units and range of measurements obtained. The scale on the two axes need not be the same size; however, each subdivision on an axis must have a constant value.
A. DRAWING A GRAPH OF EXPERIMENTAL DATA
Prepare a graph by hand based on the following experimental data:
Volume, mL 27 30 32 36 38 40
Temperature, oC 25 50 75 100 125 150
1. Draw and label the x-axis and the y-axis. Draw axes with a straight edge or ruler. Usually, the independent variable, the variable you control in an experiment, is drawn on the x-axis. The dependent variable, the variable you measure, is plotted on the y-axis. Label each axis with the appropriate unit. Since we control the independent variable it will be the variable that changes in a regular pattern.
2. Select scale for each axis . Select a scale for each axis so that the data points fill, or nearly fill, the entire page of graph paper. The subdivisions of the scale should be easy to read and interpret.
3. Place each data point clearly at the appropriate place on the graph.
4. Title the graph. The title should communicate the data represented by the graph. An example of a title to use is: dependent variable vs. independent variable.
5. Draw the best straight line through the data points. You want the line to come as close to as many of the data points as possible. Possibly, the line does not touch all data points. It represents the best averaging of data points.
6. The line drawn in step 5 can be described by the general equation: y = mx + b
In the equation, m is the slope and b is the intersection of the line along the y-axis at x =0. The slope (m) is = or
7. Answer the questions on the data sheet and attach your graph to the data sheet.
B. PRESSURE AND TEMPERATURE DATA (Micro Lab)
Pressure of a sample of air was measured at various temperatures. The following data was
obtained from these measurements:
Pressure, mm Hg 712.0 751.0 788.0 824.0 865.0
Temperature, oC 15.0 30.0 45.0 60.0 75.0
A. Which property is the independent variable? (Write answer on data sheet).
B. Prepare a graph of this data.
User name: your G00 number
Password: your SOS password. (--possibly your birth date if you have not changed it)
Click on “Start” on the desktop. Select “All Programs”, then MicroLab, and its icon.
1. MicroLab
Click on Hand Enter tab
Click OK
2. Click on: Add Column Label ( lower right of screen)
Column A
Enter a Label: Temperature
Sensor Units: Celsius
Click: OK
3. Click on: Add Column Label
Column B
Enter a Label: Pressure
Sensor Units: mm Hg
Click: OK
4. Locate Data Sources/ ( left side of screen) and look under Sensor for variables
Drag independent variable to X axis
Drag dependent variable to Y axis
5. Enter data in columns A and B
After entering the last data, click in the next column or in the space below and then Click on Accept Data. (Notice if all data points are on the graph).
6. Click on Analysis
Click on Add Curve Fit
Click OK
7. Choose Graph Series. Note Domain Minimum and Maximum.
Click OK
Choose Curve Fit
Label: Type appropriate title for graph. (Include your initials)
Curve Fit Options: First Order
Notice Correlation Factor (The correlation coefficient is a measure of how “good” the fit of the data is to the curve fit you have chosen. The closer the correlation coefficient is to 1.000, the better the relationship of data and the mathematical function chosen).
C. GRAPHING MASS AND VOLUME DATA
The following mass and volume measurements were made of five pieces of the same metal:
Mass, g: 0.0 4.8 8.0 16.0 19.0 27.0
Volume, mL: 0.0 0.5 0.9 1.8 2.1 3.0
Prepare a graph of the data. Follow steps 1-8 in B.
In Steps 2 and 3, the column label is Mass in Column A and Volume in Column B.
In Step 4, drag Mass to the y axis and Volume to the x axis.
The linear best fit line will also be the density of your sample since your y axis is mass and your x axis is volume = Density of the sample
Refer to the table below to identity the sample (closest density).
Metals/Alloys Density,
aluminum 2.70
chromium 7.09
copper 8.92
duriron 7.00
iron 7.86
lead 11.34
nickel 8.90
stainless steel 7.75
tin 5.75
Wood’s metal 9.70
Zinc 7.08
LAB 4: Part A. GRAPHING DATA SHEET
NAME____________________________ SECTION_________________
Use the temperature-volume graph that you have drawn to answer the following questions:
1. What is the independent variable? ___________________________________
2. Calculate the slope of the line you have drawn by using two points that are not data points.
Show your calculations here.
3. Using the slope from question 2 and one set of points from question 2 solve for your y intercept (b)
4. Write the equation of the line: y = _____x + _______
5. On your graph estimate the volume of gas when the temperature is 60°C? __________
6. Using equation 4 what is the volume of gas when the temperature is 60°C? _________
7. On your graph estimate the temperature when the volume of gas is 37 mL? _________
8. Using equation 4 what is the temperature when the volume of gas is 37 mL? _________
9. Why are the answers different between 5 and 6 and 7 and 8?
Attach your graph to this data sheet.
LAB 4: Part B. Pressure and Temperature
Based on your graph in Microlab:
1. What was the equation of the line of the 1st order curve fit?
2. Using question 1, what is the pressure of the sample of air at room temperature, 25°C?
3. Using question 1, what is the temperature when the air sample has a pressure of 800 mm Hg?
4. Calculate the slope of the line. (Select points that are not data points).
5. Using the slope from question 4 and one set of points from question 4 solve for your y intercept (b)
6. Write the equation for the line.
LAB 4: Part C. Mass and Volume
A. The density of the sample is_____________________________
B. The identity of the sample is______________________________
Lab 4: Graphing Data Page | 4
