Chapter 1 Chemistry and Measurements 1.7 Prefixes and Equalities

Prefixes A special feature of the SI as well as the metric system is that a prefix can be placed in front of any unit to increase or decrease its size by some factor of ten. For example, the prefixes milli and micro are used to make the smaller units: milligram (mg) microgram (μg)

Prefixes and Equalities The relationship of a prefix to a unit can be expressed by replacing the prefix with its numerical value. For example, when the prefix kilo in kilometer is replaced with its value of 1000, we find that a kilometer is equal to 1000 meters. kilometer = 1000 meters kilogram = 1000 grams

Prefixes That Increase Unit Size

Prefixes That Decrease Unit Size

Learning Check Fill in the blanks with the correct prefix: A. 1000 m = 1 ___m B. 1 x 10−3 g = 1 ___g C. 0.01 m = 1 ___m

Solution Fill in the blanks with the correct prefix: A. 1000 m = 1 ___m The prefix for 1000 is kilo; 1000 m = 1 km B. 1 x 10−3 g = 1 ___g The prefix for 1 x 10−3 is milli; 1 x 10−3 g = 1 mg C. 0.01 m = 1 ___m The prefix for 0.01 is centi; 0.01 m = 1 cm

Measuring Length Each of the following equalities describes the same length in a different unit. 1 m = 100 cm = 1 x 102 cm 1 m = 1000 mm = 1 x 103 mm 1 cm = 10 mm = 1 x 101 mm

Measuring Length The metric length of 1 meter is the same as 10 dm, 100 cm, or 1000 mm.

Measuring Volume Examples of Some Volume Equalities 1 L = 10 dL = 1 x 101 dL 1 L = 1000 mL = 1 x 103 mL 1 dL = 100 mL = 1 x 102 mL

The Cubic Centimeter The cubic centimeter (abbreviated as cm3 or cc) is the volume of a cube whose dimensions are 1 cm on each side. A cubic centimeter has the same volume as a milliliter, and the units are often used interchangeably. 1 cm3 = 1 cc = 1 mL

1 cm3 = 1 cc = 1 mL 10 cm x 10 cm x 10 cm = 1000 cm3 = 1000 mL = 1 L The Cubic Centimeter 1 cm3 = 1 cc = 1 mL 10 cm x 10 cm x 10 cm = 1000 cm3 = 1000 mL = 1 L

Measuring Mass Examples of Some Mass Equalities 1 kg = 1000 g = 1 x 103 g 1 g = 1000 mg = 1 x 103 mg 1 g = 100 cg = 1 x 102 cg 1 mg = 1000 μg = 1 x 103 μg

Learning Check Identify the larger unit in each of the following: A. mm or cm B. kilogram or centigram C. mL or μL

Solution Identify the larger unit in each of the following: A. mm or cm A mm is 0.001 m, smaller than a cm, 0.01 m. B. kilogram or centigram A kilogram is 1000 g, larger than a centigram or 0.01 g. C. mL or μL A milliliter is 0.001 L, larger than a μL, 0.000 001 L.