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Learn to calculate molarity, dilution factors, and apply solution stoichiometry in acid-base titrations. Understand how to convert mass to moles and volume to moles using molarity. Practice stoichiometric calculations, dilutions, and titration endpoint identification.
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Learning objectives • Calculate molarity and dilution factors • Use molarity in solution stoichiometry problems • Apply solution stoichiometry to acid-base titrations
Solution stoichiometry • In solids, moles are obtained by dividing mass by the molar mass • In liquids, it is necessary to convert volume into moles using molarity
Molarity (M) Molarity (M) = Moles of solute/Liters of solution • Stoichiometric calculations are facile • Amounts of solution required are volumetric • Concentration varies with T • Amount of solvent requires knowledge of density
Example • What is molarity of 50 ml solution containing 2.355 g H2SO4? • Molar mass H2SO4 = 98.1 g/mol • Moles H2SO4 = 0.0240 mol • Volume of solution = 0.050 L • Concentration = moles/volume = 0.480 M
What is concentration of solution containing 60 g NaOH in 1.5 L
Dilution • More dilute solutions are prepared from concentrated ones by addition of solvent Moles before = moles after: M1V1 = M2V2 Molarity of new solution M2 = M1V1/V2 To dilute by factor of ten, increase volume by factor of ten • Do molarity exercises
How much water must be added to make a 2 M solution from 100 mL of 6M solution?
Solution stoichiometry • How much volume of one solution to react with another solution • Given volume of A with molarity MA • Determine moles A • Determine moles B • Find target volume of B with molarity MB
Titration • Use a solution of known concentration to determine concentration of an unknown • Must be able to identify endpoint of titration to know stoichiometry • Most common applications with acids and bases
Example • How much 0.125 M NaHCO3 is required to neutralize 18.0 mL of 0.100 M HCl?