Chapter 1 Chemistry and Measurements 1.3 Units of Measurement

Units of Measurement Scientists use the metric system of measurement and have adopted a modification of the metric system called the International System of Units as a worldwide standard. International System of Units (SI) is an official system of measurement used throughout the world for units in length, volume, mass, temperature, and time.

Units of Measurement, Metric and SI

Length, Meter (m) and Centimeter (cm) 1 m = 100 cm 1 m = 1.09 yd 1 m = 39.4 in. 2.54 cm = 1 in.

Volume, Liter (L) and Milliliter (mL) 1 L = 1000 mL 1 L = 1.06 qt 946 mL = 1 qt We use graduated cylinders to measure small volumes.

Mass, Gram (g) and Kilogram (kg) 1 kg = 1000 g 1 kg = 2.20 lb 454 g = 1 lb The mass of a nickel is 5.01 g on an electronic scale.

Temperature, Celsius (oC) and Kelvin (K) Water freezes: 32 oF 0 oC The Kelvin scale for temperature begins at the lowest possible temperature, 0 K. A thermometer is used to measure temperature.

Time, Second (s) The second is the correct metric and SI unit for time. The standard measure for 1 s is an atomic clock. A stopwatch is used to measure the time of a race.

Learning Check What are the SI units for the following? A. volume B. mass C. length D. temperature

Solution What are the SI units for the following? A. The SI unit for volume is the cubic meter, m3. B. The SI unit for mass is the kilogram, kg. C. The SI unit for length is the meter, m. D. The SI unit for temperature is Kelvin, K.