Presentation on theme: "Quantitative information (qualitative data would be descriptions of your observations). Measurements represent quantities (something that has magnitude,"— Presentation transcript:
Quantitative information (qualitative data would be descriptions of your observations). Measurements represent quantities (something that has magnitude, size, or amount). Measurements
SI Measurement Scientists use the International System of Units (SI). This system was adopted in 1960 by the General Conference on Weights and Measures.
SI Base Units There are seven SI base units (meter, kilogram, second, kelvin, mole, ampere, candela). Most other SI units are derived from these. Prefixes are added to the names of the SI base units to represent quantities larger or smaller than the base units. (1000 m = 1 kilometer)
Mass is the measure of the quantity of matter (SI unit is the kilogram). Measured by using a balance. Weight is a measure of the gravitational pull on matter and is measured by using a spring scale. The SI unit for length is the meter.
Derived SI Units Combinations of SI base units form derived units. Derived units are produced by multiplying or dividing standard units. Volume is the amount of space occupied by an object. The SI unit for volume is m 3 (1 mL = 1 cm 3 ).
Density is a characteristic physical property of a substance and can be used for identification. Density is the ratio of mass to volume, or mass divided by volume (D = m/v). The SI unit for density is kg/m 3. In the lab you will usually see density expressed as g/mL or g/cm 3.
Conversion Factors Ratio derived from the equality between two different units that can be used to convert from one unit to another. Example: 4 quarts in 1 gallon
Which conversion factor should be used to convert from gallons to quarts? Let’s convert 0.75 gallons to quarts. 0.75 gallons x= quarts gallon quarts 4 1 3.0