Section 2.4

Representing Data

Graphing

• Visual display of data

• Picture demonstrating patterns

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

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

Line Graph• Most graphs in chemistry

• Points on line represent intersection of data for two variables

• Independent variable x- axis

• Dependent variable y- axis

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

Slope• Steepness of a line• Rise over run• Change in y over the change in x

y2 - y1 = Δy

x2 – x1 Δx

Interpreting Slopes• Slope rises to the right= positive slope

• Dependent variable increases as the independent variable increases

• Slope sinks to the right= negative slope• Dependent variable decreases as the

independent variable increases

Various Slopes

Interpreting Graphs• Identify independent and dependent

variables• Look at measurement units and ranges• Determine linear or nonlinear relationship• Interpret the slope

Continuous Data

• Points on line graph are connected• Interpolation: Reading areas between points• Extrapolation: Extend line beyond points