Chemistry (reacting masses) (急) thanks

Reacting Mass


In chemistry, the amount of a substance that reacts according to a balanced chemical equation. In a balanced chemical equation, the molar amounts of reactants and products are given by the numbers of each substance in the equation. The masses of each substance in the equation are in proportion to their molar masses. For example, in the reaction between carbon and oxygen, one mole of carbon (12 g) reacts with one mole of oxygen (32 g) to form one mole of carbon dioxide (44 g):

C + O2 -> CO2

Since the substances react in fixed proportion, the amount of carbon dioxide formed by any amount of carbon can be easily calculated. The amount of carbon dioxide formed will always be 44/12 times the amount of carbon. So 100 tonnes of carbon will form (100 × 44/12) or 367 tonnes of carbon dioxide. This type of calculation is very important for industrial processes where the amounts of materials being used and formed is required. Knowing the amounts of carbon dioxide formed by burning fossil fuels is important in estimating the effects of increasing carbon dioxide in global warming.

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Relative Atomic Mass

Mass of an atom relative to one-twelfth the mass of an atom of carbon-12. It depends primarily on the number of protons and neutrons in the atom, the electrons having negligible mass. If more than one isotope of the element is present, the relative atomic mass is calculated by taking an average that takes account of the relative proportions of each isotope, resulting in values that are not whole numbers.

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Relative Molecular Mass

Mass of a molecule, calculated relative to one-twelfth the mass of an atom of carbon-12. It is found by adding the relative atomic masses of the atoms that make up the molecule.

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Molar Mass

Definition: the mass of one mole of a substance, usually expressed in grams or kilograms.

Examples: GMM O2 = 32.0 g or KMM O2 = 0.032 kg

http://chemistry.about.com/od/dictionariesglossaries/g/defmolmas.htm

Formula Mass

The sum of all the atomic masses in a chemical formula.

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