Data and How to Study It Help
Chemistry is an experimental science. It is divided into two branches, pure chemistry and applied chemistry . Pure chemistry is theoretical and predicts results of experiments or observations. Applied chemistry involves the practical applications of materials and reactions. How is rust formed and how do you remove it? How can clothes get clean from washing them with soap made from ashes and fat? Why does copper turn green and then black when exposed to air? How can computer chips made from sand (silicon) carry information and electricity?
Observation and measurement, as in all science, are the keys to chemistry. In research, as in other parts of life, we are constantly measuring using common units. The baseball cleared the outfield fence by a foot. The soccer ball missed the flowerpot by three inches. The Austrian driver cruised at 160 kilometers per hour. The Kentucky Derby winner won by a length. The Olympic skier pulled into first place by two one-hundredths of a second. The soldier’s letter home weighed 1 ounce.
A chemical experiment is a controlled testing of a sample’s properties through carefully recorded observations and measurements.
Research is all about measuring. However, to repeat an experiment or follow someone else’s method, the same units must be used. It wouldn’t work to have a researcher in New York measuring in cups while another in Germany measured in milliliters. To repeat an experiment and learn from it, scientists around the world needed a common system.
In 1670, a French scientist named Gabriel Mouton suggested a decimal system of measurement. This meant that units would be based on groups of ten. It took a while for people to try it for themselves, but in 1799 the French Academy of Sciences developed a decimal-based system of measurement. They called it the metric system , from the Greek word metron , which means a measure. On January 1, 1840, the French legislature passed a law requiring the metric system be used in all trade.
International System Of Units (si)
In 1960, the General Conference on Weights and Measures adopted the International System of Units (or SI, after the French, Le Systeme International d’Unites). The International Bureau of Weights and Standards in Sievres, France, houses the official platinum standard measures by which all other standards are compared. The SI system has seven base units from which other units are calculated. Table 2.1 gives the SI units used in chemistry.
When Great Britain formally adopted the metric system in 1965, the United States became the only major nation that didn’t require metric, though people had been using it since the mid-1800s.
The advantage of the SI system is that it is a measuring system based on a decimal system. With calculations written in groups of ten, results can be easily recorded as something called scientific notation . There are written prefixes that indicate exponential values as well. Some of these are listed in Table 2.2 which lists terms used in scientific notation.
Exponential or Scientific notation is a way of writing numbers as powers of ten.
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