Sig figs made easy Or Simply sig fig By Mrs. Painter

What’s it all about, Alfie? 0

So…. simple rules 0 ALL non-zero numbers (1,2,3,4,5,6,7,8,9) are ALWAYS significant. 0 2) ALL zeroes between non-zero numbers are ALWAYS significant. 0 3) ALL zeroes which are SIMULTANEOUSLY to the right of the decimal point AND at the end of the number are ALWAYS significant. 0 4) ALL zeroes which are to the left of a written decimal point and are in a number >= 10 are ALWAYS significant.

Insignificant rules 0 Trailing zeros (those at the end) are significant only if the number contains a decimal point; otherwise they are insignificant (they don’t count) has four sig figs has six sig figs has two sig figs – unless you’re given additional information in the problem 0 4. Zeros to left of the first nonzero digit are insignificant (they don’t count); they are only placeholders! has three sig figs has two sig figs also has two sig figs!

Rules for addition/subtraction problems 0 Your calculated value cannot be more precise than the least precise quantity used in the calculation. 0 least precise quantity has the fewest digits to the right of the decimal point. 0 Your calculated value will have the same number of digits to the right of the decimal point as that of the least precise quantity.

Rules for multiplication/division problems 0 The number of sig figs in the final calculated value will be the same as that of the quantity with the fewest number of sig figs used in the calculation.

Practice time – do these on your white board as a group or on your own paper 1. Provide the number of sig figs in each of the following numbers: (a) g _____ (b) 3.40 x 103 mL ______ (c) g _____ (d) L _____ (e) g ______ (f) 1020 L _______ 2. Perform the operation and report the answer with the correct number of sig figs. (a) (10.3) x ( ) = ___________________ (b) (b) (10.3) + ( ) = ______________________ (c) [(10.3) + ( )] / [(10.3) x ( )] _____________________