Significant Figures

Significant Digits or Significant Figures We must be aware of the accuracy limits of each piece of lab equipment that we use and record our data to the proper number of significant figures. You are always allowed one estimated figure in measurements When measured quantities are given to you, it is assumed that the proper number of significant figures were recorded.

Rules for Counting Significant Figures All non-zero digits are significant _____ 785 _____ ____ Zeros: – Leading Zeros are not significant _____ 0.5 _____ _____ – Captive Zeros are significant _____ _____ _____ – Trailing Zeros are significant if there is a decimal point _____ 1.30 _____ _____ – Trailing Zeros are not significant if there is no decimal point _____ 800 _____ _____

Determine the amount of significant figures in the following examples: 967 _____ _____ _____ _____ _____ _____ 9.67 _____ _____ _____

Calculating with Significant Figures Multiply/Divide: The number with the fewest number of sig figs will determine the number of sig figs in the answer. – Example (13.92 g/cm 3 )(23.3 cm 3 ) = g 4 sig figs3 sig figs 324 g

Calculating with Significant Figures Addition/Subtraction: The number with the fewest amount of decimal places determines the amount of decimal places in the answer. – Example 3.76 g g g = g 2 decimal places 20.7 g 2 decimal places 1 decimal places