Chem 101 1st EditionExam # 2 Study Guide 1. Limiting Reactant in Chemical Reactionsa. The limiting reactant determines, or better said limits the amount of product formedi. 4CO + 3O2  4CO2 + 1O2a. CO is the limiting reactantb. (EXAMPLE) 4NH3 +5O2  4NO + 6 H2O1. 750g of both NH3 and O2 750g x 1mole NH3/ 17.03g NH3 = 44.0 Moles NH3 available 750g O2 x 1 mole O2/32.00g O2 = 23.4 Moles O2 available ThenRequired: 5 mols O2/4 mols NH3 = 1.25 mols O2/1 mols NH3Actual available: 23.4 mols O2/44.0 mols NH3 = .532mols O2/1mol NH3 .532 mols O2  not enough, therefore O2 is the limiting reactant.2. Theoretical Yield and Percent Yielda. Theoretical Yield: Maximum amount of mass of a product that can be obtained from a chemical reaction.b. Actual Yield: The mass of the product that was actually obtained.i. Usually always less that the theoretical yield c. Percent Yield: specifies how much of the theoretical yield was obtained.i. Percent Yield= Actual Yield/Theoretical Yield x 1003. Solution Concentration:a. Expressed as Molarityi. Relates to the volume of solution in liters to the amount of solute.1. A solute is any substance (solid, liquid or gas) that is dissolved in solvent ii. Molarity = moles/Liters 1. Represented by the letter “c”a. Molarity of x (cx) = amount of solute ( x) mol/volume of solutionb. EXAMPLE:i. If 58.4g (1 mole) of NaCl is dissolved in enough water to give a total solution volume of 1 Liter, the Molarity, c, is 1 mol/L1. M=moles/Liters4. Preparing Solutions of Known Concentrationa. Suppose you need 2 L of a 1.5 M solution of aqueous of CaCl22L x 1.5 mols CaCl2/1L = 2 mol CaCl2Then convert to grams to find the concentration.With the findings, this is the amount of grams needed to dissolve to prepare the desired solution in enough water to make 2L of solution.- Another method of making a solution of a given concentration is tobegin with a concentration solution and add more solvent (usually water ) unit the desired, lower concentration is reached5. pHa. the pH of a solution is the negative of the base : -10 logarithmi. pH = -log[x]6. Stoichiometry a. You want to find out the mass of a compound that is required to react completely.i. L of M a. For a thorough very helpful explanation f many steps and practices visit pg 165 in the book. 7. Thermodynamics:a. The science of heat and worki. Thermal Energy: is used to when refereeing to kinetic energyii. System: an object ( or collection of objects) being studiediii. Surrounding: includes everything outside the system that can exchange energy and/or matter with the systemiv. Exothermic: energy is transferred as heat from a system to its surroundings( loses heat)v. Endothermic: the exact of opposite exothermic ( gains heat) 8. Specific Heat Capacitya. Represented by the letter “C”i. Q= C x m x Change in Tempti. Change in Tempt= Final temperature – the initial TemperatureHere are some sites that are helping me further prepare for the test:- http://chemwiki.ucdavis.edu/Physical_Chemistry/Thermodynamics/State_Functions/Enthalpy-