Labs from Units 2, 3, and 4: Guided Inquiry: Molarity, Set Up Lab Equipment, Begin Lab Set Up

Warm Up In your Warm Up Section, answer the following questions: How many moles are in 45.3 grams of aluminum oxide? What can you to make a 1 Molar solution of it? TIME: 6 MINUTES WHEN DONE: Share out with your table partners

Agenda Finish Notes on Molarity, Dilution, and Titration Check Out Lab Equipment – Again Guided Inquiry: Molarity Set Up: Lab Notebook

volume of solution in liters Molarity The quantity of solute in a solution can matter to a chemist. We call the amount dissolved its concentration. Molarity is one way to measure the concentration of a solution: moles of solute volume of solution in liters Molarity (M) =

Mixing a Solution To create a solution of a known MOLARITY, weigh out a known mass (and, therefore, number of moles) of the solute. Then add solute to a volumetric flask, and add solvent to the line on the neck of the flask.

3 STEPS TO CALCULATING MOLARITY Convert solute to moles (using molar mass) Convert solvent to liters Divide: moles of solute Liters of solvent

Molarity Check Which is more concentrated, a solution prepared by dissolving 21.0 grams of NaF in enough water to make 500 mL of solution, or a solution prepared dissolving 10.5 g of NaF in enough water to make 100 mL of solution? 0.500 mol / 0.500 L = 1 M 0.250 mol / 0.1L = 2.5 M © 2015 Pearson Education, Inc.

Molarity Check What is the concentration of ammonia (NH3) in a solution made by dissolving 3.75 grams of ammonia in 120.0 L of water? How many grams of Na2SO4are there in 15 mL of 0.50 M Na2SO4? How many mL of 0.50 M Na2SO4 solution are needed, if you are given 0.038 mol of Na2SO4? © 2015 Pearson Education, Inc.

Molarity Check What is the molar concentration of K+ ions in a 0.015 M solution of potassium carbonate? © 2015 Pearson Education, Inc.

Dilution One can also dilute a more concentrated solution by using a pipet to deliver a volume of the solution to a new volumetric flask, and adding solvent to the line on the neck of the new flask.

Dilution The molarity of the new solution can be determined from the equation M1  V1 = M2  V2, where M1 and M2 are the molarity of the concentrated and dilute solutions, respectively, and V1 and V2 are the volumes of the two solutions.

Dilution: Check You are given 250 grams of Copper II Chloride dissolved and you dissolve it in 360 mL of water. You then notice that your solution is WAY TOO concentrated. You only need to make a 0.050 M solution of Copper II Chloride, not the one you made. How much more water do you need to add to make 0.05 M Copper II Chloride?

Dilution: Check 1.75 mL 8.75 mL 48.6 mL 28570 mL What volume of a 1.00 M stock solution of glucose must be used to make 500 mL of a 1.75 x 10-2 M glucose solution? 1.75 mL 8.75 mL 48.6 mL 28570 mL

Using Molarities in Stoichiometric Calculations

Titration A titration is an analytical technique in which one can calculate the concentration of a solute in a solution.

Titration A solution of known concentration, called a standard solution, is used to determine the unknown concentration of another solution. The reaction is complete at the equivalence point.

Lab Equipment FIND YOUR BINS: Spread Out to Other Tables FILL: ALL Bins with 2-3 Paper Towels Each CHECK OUT: Lab Equipment IF YOU ARE MISSING ANY ITEM: Let me know/DO NOT check it off TIME: 11 MINUTES WHEN DONE: Work on Guided Inquiry: Molarity

Guided Inquiry: Molarity COMPLETE: Molarity Guided Inquiry WORK: Together USE: Notes and each other TIME: 15 MINUTES WHEN DONE: Turn into class box and begin reading pre-lab

SET UP LAB NOTEBOOK