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Lecture 2 stoichiometry

Law of chemical combination. when a piece of wood was burned. The resulting the ash weighed is less than the wood itself. One theory was that something called phlogiston was evolved during combustion.. Law of definite proportion . This law states that in any sample of a pure chemical substan

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Lecture 2 stoichiometry

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    1. 1 Lecture 2 stoichiometry Law of chemical combination Law of definite proportion The Mole concept Formula Mass Molar Mass Relationship among these terms Avogadro's number Calculations Stoichiometric calculations in chemical equations: Mole-mole Mole-mass Mass-mass

    2. Law of chemical combination when a piece of wood was burned. The resulting the ash weighed is less than the wood itself. One theory was that something called phlogiston was evolved during combustion.

    3. Law of definite proportion This law states that in any sample of a pure chemical substance, we always find the same elements in the same definite proportions by mass.

    4. Law of definite proportion This law states that in any sample of a pure chemical substance, we always find the same elements in the same definite proportions by mass.

    5. Combustion involves the reaction of the substance with the Oxygen. There is no change in mass during combustion. Law of conservation of mass, state that in any chemical reaction, mass neither created nor destroyed

    6. For example in water we always find the H and O in the ratio of 1g of H: 8 g of O. 1 g H : 8 g of O the ratio 1:8 2g H : 16 g of O the ratio 1:8

    7. All compounds have a similar fixed ratios by the mass of their elements.

    8. 8 THE MOLE In chemistry, particles such as atoms, molecules, and ions are counted by the mole. A mole: is a unit that contains 6.022 x 1023 items (PARTICLES) A mole is the amount of substance that chemists often use to measure chemicals. One mole of an element is its relative atomic mass in grams. example: C = 12, so one mole of carbon atoms weighs 12g. The number of particles in one mole of a substance is 6.022 x 1023 (Avogadro's number) 1 dozen = 12 objects 1 mole = 6.022 x 1023 objects C atom + O atom CO molecule l mole C + l mole O 1mole CO (6.022 x 1023 atoms C) + (6.022 x 1023 atoms O) (6.022 x 1023 molecule CO)

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