Chemistry – Apr 24, 2018 Get out Limiting Reactant Worksheet for HMK check Do Now – Consider the reaction NH3 + O2 NO + H2O (balance first!!) If 3.25 g of NH3 are allowed to react with 3.50 g of O2, a) which is the limiting reactant and b) how many grams of NO are formed? Today’s Objective – Molarity Agenda Hmk Review Molarity Solution Stoichiometry Assignment: Molarity Worksheet
Concentrations of Solutions The concentration of a solution designates the amount of solute dissolved in a volume of solvent to create a solution. The greater the amount of solute dissolved in a certain amount of solvent, the more concentrated the solution is. Qualitatively, concentration can be represented by color intensity.
Molarity By far, the most common concentration unit: Watch your units. Amount of solute must be in moles, not grams. Amount of solution must be in Liters, not mL or grams. Ex: What is the molarity of a solution of 3.25 mol of NaHCO3 dissolved in 750 mL of water? Ex: How many moles are there in 75 mL of a 3.5 M NaOH solution? Ex: What volume of a 1.50 M AlCl3 solution is needed to obtain 0.250 mol AlCl3? Ex: What is the molarity of a solution if 75.0 g of Ca(OH)2 is dissolved in 650 mL of water?
Complete Stoichiometry Grams of X Not Here!! Grams of Y Gas Volume of X Gas Volume of Y 22.4 L 22.4 L Molar mass Molar mass Molarity of X Molarity of Y Reaction Coefficients Moles of X Moles of Y X X Macroscopic scale Volume of X Volume of Y 6.022x1023 6.022x1023 Reaction Coefficients Number of X Number of Y Atomic scale
Solution Stoichiometry Practice How many grams of NaOH are needed to neutralize 20.0 mL of 0.150 M H2SO4 solution? How many liters of 0.500 M HCl(aq) are needed to react completely with 0.100 mol of Pb(NO3)2(aq), forming a precipitate of PbCl2(s)?
Exit Slip - Homework Exit Slip: How many moles of HCl are present in 15.3 mL of a 0.500 M solution? What’s Due? (Pending assignments to complete.) Molarity worksheet What’s Next? (How to prepare for the next day) Read p100-102, p224-232, 241 p246-247