219731628-Hukum-hukum-Dasar-Kimia.txt - Hukum-hukum dasar...

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Hukum-hukum dasar kimia: understanding of matters Widya Ernayati K.
Apa saja komposisi dari materi itu? • Democritus (460-370 BC)matter is ultimately composed of indivisible particles atom • Robert Boyle 17th century an element is composed of "simple Bodies. . . of which all mixed Bodies are compounded." • Dalton 19th century  propose atomic model and mass law • dst
Classification of Matter: an atomic overview
Element/Unsur • the simplest type of matter with unique physical and chemical properties • Example: silikon, oksigen, tembaga • consists of only one kind of atom • cannot be broken down into a simpler type of matter by any physical or chemical methods Mengapa sifat fisik Silikon, Oksigen, Tembaga tidak Sama?  each element is unique because the properties of its atoms are unique
Element
Compound/senyawa • a type of matter composed of two or more different elements that are chemically bound together • Example: amonia, water, carbon dioxide • the elements are present in fixed parts by mass (fixed mass ratio). • its properties are different from those of its component elements • a compound can be broken down (chemical change) into simpler substances-its component elements
Compound
Mixture • a group of two or more substances (elements and/or compounds) that are physically intermingled • the components of a mixture can vary in their parts by mass • At the atomic scale, a mixture is merely a group of the individual units that make up its component elements and/or compounds • A mixture retains many of the properties of its components • mixtures can be separated into their components by physical changes
Hk dasar kimia: atomic view of matters • • • • Hukum kekekalan massa Lavoisier Hukum perbandingan tetap Joseph Proust Hukum perbandingan berganda Dalton Hukum perbandingan volume Gay Lusac
Hukum Kekekalan Massa: Antoine Lavoisier ( 1 743-1 794) “the total mass of substances does not change during a chemical reaction” 2 Hg + O2  2HgO Mau bukti???
Hukum kekekalan massa 3,25 g 3,32 g 6, 57 g 4,55 g 2,02 g 6,57 g “matter cannot be created or destroyed”
Hukum Perbandingan Tetap: komposisi tetap the elements are present in fixed parts by mass (fixed mass ratio) in compound “ no matter what its source, a particular compound is composed of the same elements in the same parts (fractions) by mass” • Fraksi massa = massa tiap unsur massa total senyawa • Persen massa (%) =massa tiap unsur x 100% massa total senyawa
Hukum Perbandingan Tetap: komposisi tetap • • • 10 3 12 • The law of definite composition tells us that pure samples of calcium carbonate, no matter where they come from , always contain these elements in the same percents by mass
Aplikasi Hk Perbandingan Tetap • Mencari massa unsur dalam suatu senyawa Contoh soal!!! • Pitchblende is the most commercially important compound of

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