10ChemH - Measurements, Sig Figs, Calculations, Dimensional Analysis

what is the 1st rule for assigning sig figs?

all non-zero digits are significant (12.1754→6 sig figs)

what is the 2nd rule for assigning sig figs?

all numbers written in scientific notation are significant (3.20700e15→6 sig figs)

what is the 3rd sig fig rule?

zero?

• leading zeroes do not count (0.0002070→4 sig figs)

• trailing zeroes do not count with no decimal place

  • 1500→2 sig figs

  • 1500.→4 sig figs

  • 1500 (overlined)→4 sig figs

  • 1500.00→6 sig figs

adding/subtracting sig figs

round to the least decimal place

• 88.10976 (5) + 15.4382 (4) + 19.617 (3) = 123.16496→123.165

multiplying/dividing sig figs

round to the least sig fig

powers/roots with sig figs

round to the same sig fig

bases for dimensional analysis

• kilo=1,000

• 100=centi

• 1,000=mili

• 1(10^6)=micro

• 1(10^9)=nano

base units

• length (meters)

• mass (grams)

• volume (liters)

extra length conversions

• 2.54 cm=1 in

• 1609 m=1 mile

extra mass conversion

454 g=1 lb

extra volume conversions

• 3.78 L=1 gallon

• 1 mL=1 cm³