1. Section 2.4
Representing Data

2. Graphing
Visual display of data
Picture demonstrating patterns

3. Circle Graph
Pie chart
Good for parts of a fixed whole
Percentages

4. Bar Graph Shows quantity variations with factors
Independent variable  horizontal axis (x)
Dependent variable  vertical axis (y)

5. Line Graph Most graphs in chemistry
Points on line represent intersection of data for two variables
Independent variable  x- axis
Dependent variable  y- axis

6. Best Fit Line
Best fit line  line drawn so that the same amount of points fall above and below it
Look at the slope of this

7. Slope Steepness of a line Rise over run
Change in y over the change in x
y2 - y1 = Δy
x2 – x1 Δx

8. Interpreting Slopes Slope rises to the right= positive slope
Dependent variable increases as the independent variable increases

9. Slope sinks to the right= negative slope
Dependent variable decreases as the independent variable increases

10. Various Slopes

11. Interpreting Graphs Identify independent and dependent variables
Look at measurement units and ranges
Determine linear or nonlinear relationship
Interpret the slope

12. Continuous Data Points on line graph are connected
Interpolation: Reading areas between points
Extrapolation: Extend line beyond points