Conversions Using the metric system

Common Decimal Prefixes Used with SI Units

 Notice in the middle of the chart where it is marked base unit * any prefix above the base unit scales the unit up, and prefix below the base unit scales the unit down. Examples : Scale up kilo scales base units by a 1000 ( 10 3 ) according to the chart so if you add that to a base unit like grams we could come up with this kilograms = 1 gram or there are 1 kilogram (kg ) = 1000 grams (g) Scale down milli scales base units down by ( ) according to the chart so if you add that to a base unit like grams we could come up with this milligrams( mg) = 1 gram (g) or there are 1000 milligrams (mg)= 1 gram (g) * any unit without a prefix is a base unit like grams, liters, meters. bigger unit smaller unit

Study Sheet!

Units  Always write every number with its associated unit  Always include units in your calculations  you can do the same kind of operations on units as you can on numbers  cm × cm = cm 2  cm + cm = cm  cm ÷ cm = 1  using units as a guide to problem solving is called dimensional analysis Tro: Chemistry: A Molecular Approach, 2/e

Conversion Factors A conversion factor is a fraction obtained from an equality Equality: 1 in. = 2.54 cm ( this is non metric and would be given on a test ) written as a ratio with a numerator and denominator is inverted to give two conversion factors for every equality 1 in. and 2.54 cm 2.54 cm 1 in. Equality: 1000mm = 1 m ( this is metric and would not be given on a test ) written as a ratio with a numerator and denominator is inverted to give two conversion factors for every equality 1000mm and __1m__ 1m 1000 mm

Update your Study Sheet!

Problem Solving and Dimensional Analysis  Arrange conversion factors so the starting unit cancels  arrange conversion factors so the starting unit is on the bottom of the first conversion factor  May string conversion factors  so you do not need to know every relationship, as long as you can find something else the starting and desired units are related to Tro: Chemistry: A Molecular Approach, 2/e

A rattlesnake is 2.44 m long. How long is the snake in centimeters? STEP 1 Given 2.44 m Need centimeters STEP 2 Plan meters centimeters STEP 3 Equality 1 m = 100 cm Conversion Factor 1 m and 100 cm 100 cm 1 m STEP 4 Set up problem 244 m x 100 cm = 244 cm (answer 3SF) 1 m Example

More Practice A coin contains 2.5 x 10 5 micrograms of nickel. How many grams of nickel are in the coin?

More Practice A piece of rope is 9.2 x kilometers. How many decimeters of rope is there?

Your Turn! How many grams does a 4334 kg sample contain?

Your Turn! How many µL does a 2.01 x ML sample contain?