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This 3 page Class Notes was uploaded by Kim Notetaker on Sunday September 18, 2016. The Class Notes belongs to Chem 111 at California State University Chico taught by in Fall 2016. Since its upload, it has received 7 views. For similar materials see General Chemistry in Science at California State University Chico.
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Date Created: 09/18/16
Chapter 3: Mass Relationships in Chemical Reactions Particle : ? Particle +: ?+ Chemical Change Reactions Representations: Equators: Repetants (are on the left) to products (on the right) Arrow: sepierates starting and ending material States: gas (g) liquid (l) solid (s) and solution (aq) Stoichiometric Coefficients: before formulas Mass Conservation: Law of conservation or mass Balances: 1. Write an unbalanced equation using the correct chemical formula for each reactant and product H 2 g +O →2 O 2 (L ) 2. Find suitable coefficients – the numbers placed before formulas to indicate how many formula units of each substance are required to balance the equation 2 H 2(g)+O 2(g →2 H O2 L ) 3. Reduce the coefficients to their smallest whole number value, if necessary by dividing all by the common divider Chemical arithmetic stoichiometry Stoichiometry: the chemical arithmetic needed for a molemass conversions Molar mass vs. Formula mass vs. molar mass HCl: 1 mole = 36.5g 6.022×10 23 moles = 1 mole HCl =36.5g C 2 4 : 1mole = 28.0g 6.022×10 23 C 2 4 molecules = 1 mole = 28.g aA+bB→cC+ⅆD Grams of Moles of Moles of Grams of a. A b B Molar Mass of A Mole ratio between Molar Mass of B A & B (coefficients) How many grams of H 2 ? N 23H →22N H 3 g of Moles of Moles of g of N 2 N 2 H 2 H 2 5gN N H H 2 1 mole 2 3 mol 2 2g 2 N N H 28g 2 1 mol 2 1 mol 2 Yield of Chemical Reactions: Yield: the amount product formed in a reaction Actual vs. Theoretical Actual yield of product x 100 Percent Yield: Theoretical yield of product x 32×0.75= ×32;x=24 32g Reactions with limiting amounts of reactions Limiting Reactant: the reactant that a present is limiting amount will form the lowest amount of product. Excess Reactant: any of the other reactants still present after determination of the limiting reactant Percent Composition and Empirical Formula Percent Composition: Expressed by identifying the elements present and giving the mass precent of each Empirical Formula: it tells the smallest whole number ratios of thee atoms in the molecules Molecular Formula: it tells the actual number of atoms in a molecule. It can be either the empirical formula or a multiple of it Molecular Mass Multiple = Empirical formula Mass
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