Catalyst 1. Identify the oxidized a reduced species in the reaction below: S2O32- + 4Cl2 + 5H2O  HSO42- + 8H+ + 8Cl- Write the reaction for: 2. Magnesium metal is reacted in air. End

Lecture 3.4 – Moles, Molarity, and Dilutions

Today’s Learning Targets LT 3.7 – I can explain the concept of the mole and why it is an adequate means by which to express the amount of given substance. LT 3.8 – I can determine the molarity of an unknown solution. Furthermore, I can determine the number of grams of substance in a solution if the molarity and volume are given. LT 3.9 – I can determine the new concentration of a solution if a dilution is performed.

The Mole Recall that Avogadro proposed that 1 mole = 6.022 x 1023 particles. If you have 1 mole this means you have 6.022 x 1023 of this substance.

Grams to Moles Review We can convert between the amount of a substance to moles by using the molar mass.

Table Talk You have 5.380 g of C6H12O6, how many moles do you have?

Molarity Recall, we can calculate the concentration of solution using the molarity.

Class Example How many grams of Na2SO4 are required to make a 0.350 L of 0.5 M Na2SO4

Table Talk How many grams of KNO3 are there in 15 mL of 0.5 M KNO3

Dilutions If we change the volume of a solution, the molarity will also change. We can calculate the new molarity of a solution if the initial and final volume are known.

Class Example How many mL of 3.0 M H2SO4 are needed to make 450. mL of 0.10 M H2SO4?

Table Talk How many mL of 5.0 M K2Cr2O7 solution will be diluted to prepare 250 mL of 0.1 M solution?

Connect 4

Exit Ticket Calculate the molarity of a solution that contains 52 g of H2SO4 and occupies a volume of 250. mL How many grams of AgNO3 are there in a 4.50 M solution that occupies 3.5 L? If you have a stock solution of AgNO3 that is 3.24 M, what is the new concentration if you add 3 mL of this solution and dilute it to 500 mL?

Lab and Review of Unit Content Lab and Review of Unit Content Monday Tuesday Wednesday Thursday Friday 24 25 26 27 28 1 2 3 4 5 8 9 10 11 12 Lab and Review of Unit Content Lab and Review of Unit Content Stoichiometry, Empirical Formulas, and Limiting Reactant Stoichiometry, Empirical Formulas, and Limiting Reactant Copper and Iodine Empirical Formula Lab Period 5 Unit 3 Exam Period 2 Unit 3 Exam NO SCHOOL! National Holiday: Mr. Lance’s Birthday Review for Mock AP Exam Review for Mock AP Exam Period 5 Mock AP Exam (All Unit 1 – 3 Content Covered) Period 2 Mock AP Exam (All Unit 1 – 3 Content Covered)

Closing Time Read 4.1 – 4.5 Complete homework 3.4