Chapter 3: Scientific Measurement
Celsius scale
the temperature scale on which the freezing point of pure water is 0 degrees, and its boiling point is 100 degrees; formerly known as the centigrade scale because one degree is 1/100 (centi-) of the way from freezing to boiling of pure water.
weight
a force that measures the pull of gravity on a given mass; varies with distance from the center of gravity of the earth.
temperature
a measure of the average kinetic energy of the particles in a sample of matter; particles with a higher ___________ have a higher average kinetic energy (energy of motion) than particles with a lower temperature.
gram (g)
a metric unit of mass equal to the mass of one cubic centimeter (or mL) of pure water at 4 degrees Celsius)
dimensional analysis
a problem-solving technique that uses conversion factors made up of units that are part of the measurements to help solve the problem; aka factor-label method, since the labels (units) of the factors (measurements) are used in solving the problem.
measurement
a quantitative description that includes both a number and a unit; for example, 153 L.
experimental value
a quantitative value measured during an experiment.
conversion factor
a ratio of equivalent measurements used to convert a quantity from one unit to another; for example, 1 kilogram = 1000 grams is a ratio of equivalent measurements that can be used to convert 5.13 kg to 5130 g.
accepted value
a value accepted by the scientific community to be accurate for a given quantity.
International System of Units
aka SI, for Systeme International; the revised version of the metric system adopted by international agreement in 1960; currently in use by all but 3 countries in the world (Liberia, Myanmar, United States of America).
significant figures
all the digits that can be known precisely in a measurement, plus one estimated digit; these digits are determined by the markings on your measuring tool, and we use them to communicate how well we know a measurement.
scientific notation
an expression of numbers in the form m x 10^n where m is equal of greater then 1 and less than 10, and n is an integer; used when numbers are very small or very large.
precision
describes the closeness of a set of measurements taken under the same conditions. If several measurements are close to each other they are _______; if they are close to the accepted value they are accurate. Therefore, measurements can be _______ without being accurate, but if several measurements are accurate, they must be _______!
joule
the SI unit of energy; 1 calorie = 4.184 J
meter (m)
the base unit for length in the SI; equal to 1/10,000,000 the length of a meridian from the North Pole to the equator (no joke!!); also equal to 100 centimeters (1 cm - 1/100 m; centi- means 1/100!).
energy
the capacity (ability) for doing work or producing heat; measured in units such as calories and Joules.
accuracy
the closeness of a measurement to its accepted true value.
error
the difference between the accepted value and the experimental value.
kilogram
the mass of 1 liter of pure water at 4 degrees Celsius; it is the base unit for mass in the SI (metric system); equal to 1000 grams.
percent error
the percent that a measured value differs from the accepted value; calculation: (|accepted value - experimental value|/accepted value) x 100 = % error.
calorie (cal)
the quantity of heat needed to raise the temperature of 1 gram of pure water by 1 degree celsius; when written with a capital C, as in ______ of food energy listed on packages, it refers to 100,000 ______ with a lower case c.
density
the ratio of the mass of an object to its volume; tells how much matter is contained in a given volume of a sample of matter; given in units of mass per volume, for example g/mL, or kg/L.
Kelvin scale
the temperature scale on which the freezing point of water is 273 K and its boiling point is 373 K; 0 K is called absolute zero, at which all particle motion stops (absolutely zero motion); equal to -273.15 degrees Celsius. Remember, temperature is a measure of average kinetic energy, or the energy of motion. Neither the term nor the symbol for degree is used with the Kelvin scale; we simply say "273 Kelvins."
liter (L)
the volume of a cube measuring 10 cm on each edge (10 cm x 10 cm x 10 cm = 1000 cm3 = 1000 mL = 1 L)
absolute zero
the zero point on the Kelvin scale, at which all particle motion stops (absolutely zero motion); equal to -273.15 degrees Celsius. Remember, temperature is a measure of average kinetic energy, or the energy of motion.
