Chemical Reactions Outline

Chemical Reactions Outline - • Law of Conservation of...

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CHEMISTRY 120 – CHAPTER 5 – REVIEW Chemical Reactions and Quantities Physical change: no bonds are broken, state or appearance change. Chemical change: bonds are broken and/or formed. A new substance forms. Chemical equations: the language of chemistry. o Formulas: identify reactants (left) and products (right). o Subscripts: gives the number of atoms of an element in a given molecule. o States: gas (g), solid (s), liquid (l), aqueous (aq). o Balancing: the number and type of atoms in reactants = same must be in products. Use coefficients (numbers in front of formulas) to balance. Procedure for balancing: Place a 1 in front of the formula with the most atoms. Balance other formulas with atoms in above formula. If one does not work, try a two. Mole: 6.02 x 10 23 . The number C-12 atoms in 12 grams. Also called Avogadro’s number. Molar mass: the mass of one mole of a substance (element or compound). Grams/mole o The sum of the atomic masses that make up an element or compound. o Use as a conversion factor: 1 mole = X grams.
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Unformatted text preview: • Law of Conservation of Mass: mass cannot be created or destroyed. o Mass of products = mass of reactants • Mole ratio: in a balanced chemical equation, it is the ratio of moles of any two compounds. • Mass calculations: Using a balanced chemical equation. o Mass A x 1 Mole A/Mass A = Moles A o Moles A x Moles B/Moles A = Moles B o Moles B x Molar Mass B/1 mole = Mass B • Exothermic reaction: heat is released during a reaction. o Heat is a product. o Energy level of products is lower than the energy level of reactants. • Endothermic reaction: heat is absorbed during a reaction. o Heat is a reactant. o Energy level of reactants is lower than energy level of products. • Reaction rate: how fast a reaction occurs. o Temperature: increasing temperature increases the reaction rate. o Catalysts: using a catalyst increases the reaction rate. o Reactant concentration: increasing this increases the reaction rate....
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