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Olympic High School AP Chemistry Name __________________________________ Period ___ Date ___/___/___ 4 Chemical Equations and Stoichiometry STUDY I can: Chemical Equations Limiting Reactant Problems Give examples of products and reactants in a chemical equation. State that Antoine Lavoisier introduced the law of conservation of matter. Combustion State that combustion is another name for burning. Write an equation for a combustion reaction given only the fuel that is burned. Correctly label substances in an equation as solid (s) , gas (g), liquid (l), or aqueous (aq) Balancing Equations Balance equations by adding coefficients. Recognize when an equation is balanced. State that the formulas of reactants and products should not be changed in order to balance equations. Stoichiometry Problems Use the stoichiometric factor ( of the problem) to convert from moles of one substance to moles of a different substance. (i.e. In the equation: N2 + 3H2 2NH3, 3 mol H2 2 mol NH3) Convert between the quantities of mass, volume, molecules and moles using dimensional analysis (i.e. use 1 mol = 22.4 L, 1 mol = 6.02 x 1023 molecules, and 1 mol = gram molecular mass) Show the units of molar mass as grams/mol or g·mol-1. LIST Recognize that a problem with two “given values” is a limiting reactant problem. Determine the limiting reactant and excess reactant in a problem. Solve problems involving Limiting Reactants Calculate how much excess chemical is left over after a reaction. Percent Yield Problems Use stoichiometry to calculate the theoretical yield (mass of a product) in a problem. State that actual yields are usually given in a problem. Use the theoretical yield and actual yield to calculate the percent yield. Chemical Analysis Problems Calculate the mass of each element in a given compound given data such as the masses of CO2 and H2O formed in a combustion reaction. Use mass and mole information to calculate the empirical formula of an unknown substance. Use percent composition to equalize mass and mole information derived from different samples. Continuous Variation Data Use “continuous variation” laboratory data to determine the correct mole ratio of an equation. (Micro Mole Rockets Lab) Measuring Concentrations of Cmpds. in Solution Know the definition of molarity, M, as one way to communicate concentration of solute. Know that the symbol [X] means the concentration of X in moles/Liter. Be able to determine the concentration of ions in an ionic compound. For example, in 0.25 M AlCl3 [AlCl3] = 0.25 M [Al3+] = 0.25 M [Cl] = 0.75 M Use the molarity formula to calculate moles, mass, volume, or molarity of a solution. Know that Volume x Molarity = moles of solute. Dilution problems use ViMi = VfMf. Describe how to make a solution correctly. Know what a volumetric flask is. Stoichiometry of Reactions in Aqueous Solution Use molarity as another conversion factor to solve stoichiometry problems. Know that titration is a technique called quantitative chemical analysis because you are measuring. It is also called volumetric analysis (because you are measuring volumes). [Note: qualitative analysis involves no measurements such as using solubility rules to determine the identity of an unknown ionic compound.] Understand the terms indicator, equivalence point, standardization, and primary standard. Know common indicators such as phenolphthalein for titrations with strong bases. Understand that a titration can be done with an acid-base reaction or a redox reaction. In each case, some sort of indicator must be used to tell when equivalent amounts of reactants have been mixed