1 / 18

Chemistry SM-1232 Week 6 Lesson 2

Chemistry SM-1232 Week 6 Lesson 2. Dr. Jesse Reich Assistant Professor of Chemistry Massachusetts Maritime Academy Fall 2008. Class Today. Take Home Quiz Friday No class on Friday Review: Solution Concentration, mass percent, Molarity,

rane
Télécharger la présentation

Chemistry SM-1232 Week 6 Lesson 2

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chemistry SM-1232Week 6 Lesson 2 Dr. Jesse Reich Assistant Professor of Chemistry Massachusetts Maritime Academy Fall 2008

  2. Class Today • Take Home Quiz Friday • No class on Friday • Review: Solution Concentration, mass percent, Molarity, • Wednesday- stoich, Freezing point depression, boiling point elevation • Friday: Take home quiz will be posted on the wiki under week six • Monday- Chapter 14, HW due • Wednesday- WE DO HAVE CLASS • Friday- On Break

  3. Mass Percent • Mass is similar to how much it weighs • Percent: How much per 100 units. • In this case, how much of the mass comes from 1 part of the total mass?

  4. Mass Percent Mass of Solute X 100 = mass percent Mass of Solution Quick percent trick: Percent always means divide the little number by the big number and multiply by 100.

  5. MOLARITY!!! • This is a huge topic!!! A ton of chemistry is done in solutions!!! THIS IS HOW WE UNDERSTAND IT!!! • YOU MUST REMEMBER WHAT IS ON THE NEXT SLIDE!!!

  6. Molarity • Molarity = M • M = moles solute/ L of solution • THIS IS A CONVERSION FACTOR BETWEEN LITERS OF SOLUTION AND MOLES!!!!!!!!!!!!

  7. Ion Conentration • Remember how I showed you how ions dissolve in water? What you saw was NaCl dissolving. • For each molecule of NaCl that dissolves how many Na atoms go into the water? How many Cl atoms go into the wateR? • Would the same be true of CaCl2? How many Ca atoms go into solution for 1 molecule of CaCl2? Cl atoms?

  8. Ion Concentration Calcs • You have a 2.8M solution of AlCl3. In 1 L of solution how many moles of Al atoms are in solution? How about Cl atoms? • If you have 275mL of solution how many moles of Al are in the solution? How many moles of Cl are in the solution?

  9. Solution Dillution • M1V1=M2V2 • This is the equation to use to figure out what happens to the number of moles as we change the volume.

  10. New Material: Freezing Point Depression • Salt lowers the melting point of ice. • Salty icewater baths are below 0C. • To figure out how much the depresion will be we’ll need to use Molality (m)

  11. Molality • Molality (m) = Moles Solute/ kg Solvent.

  12. Molality • Calculate the molality of a solution containing 44g of ethanol (C2H6O) in 300mL of water.

  13. Freezing Point Depression • The change in temperature = Molality x the freezing point depression constant • DTf= m x Kf • Kf of water = 1.86 Ckgsolvent/mol solute

  14. Example • Calculate the freezing point depression of a 2.3 m ethylene glycol solution.

  15. Boiling point elevation • DTb= m x Kb • Kb water = 0.512 Ckgsolvent/mol solute • Calculate the boiling point of a 3.4 m solution of ethylene glycol

  16. Mole Map • We’re going to create a mole map in class. It will look like a tournament bracket of sorts. On the left you’ll have grams, volume of gas at stp, Liters of solution (and molarity), and atoms (and molecules). Those will focus down to 1 place which will have moles A as the units. It will then go to Moles B. Then you’ll expand back out to grams, volume of a gas at stp (molarity), liters of solution, and atoms (molecules). Above each line you’ll write what to multiply by to change from one unit into another.

  17. Practice Stoich • Use the following reaction. Sodium carbonate (Na2CO3) and water decompose into NaOH and Carbon Dioxide. • Convert the following: • 325g Na2CO3 into L of CO2 • 2L of a 2.5M solution Na2CO3 into grams NaOH • 55.43L of CO2 into moles Na2CO3 • 5g Na2CO3 into a 5L solution of X Molar NaOH • 3 Moles of NaOH into moles of CO2 • 69.4g Na2CO3 into molecules and atoms of O2 and O

  18. To Do • Be ready for your quiz on Friday!!! Due Monday.

More Related