To Do… OWL Lab Exam 3 Chapter 14 due Tuesday, April 24 Exam 3 review due Wednesday, April 25 Exam 3 Thursday, April 26

Exam 3 Thursday, April 26, 7:00 pm–8:30 pm; Rooms on the website (same). Conflict: April 26; 5:00 pm – 6:30 pm in 1022 Lincoln Hall; sign up in 1026 CA Practice exam will be posted online. See me right away if you have a conflict with the exam and conflict times.

Review Sessions Tuesday, April 24 165 Noyes Lab 7:00-9:00 pm

Final Exam Friday, May 11, 8:00 am – 11:00 am 100 Noyes Lab Hour exams (this semester’s and practice exams) will be posted. There is no conflict exam scheduled. See me for University-sanctioned conflicts. We will discuss the Final Exam during lecture on Tuesday, May 1.

Intermolecular Forces (IMFs)

London Dispersion Forces

London dispersion forces All molecules exhibit these forces. Due to temporary and induced dipoles. Strongest IMFs for non-polar molecules Examples include nitrogen (N2) and methane (CH4). With more electrons, more chance of an induced dipole.

Dipole-dipole interactions

Dipole-dipole interactions Polar molecules exhibit these forces. (also exhibit LDFs) Due to permanent dipoles. Stronger IMFs for than LDFs (given similar sized molecules). Some polar molecules (such as H2O) exhibit a special kind of dipole-dipole interaction.

Water is a Liquid!

Hydrogen Bonding in Water

Clicker Question How many of the following interactions does CH3CH2CH3 exhibit? London dispersion dipole-dipole hydrogen bonding A) 0 B) 1 C) 2 D) 3

Clicker Question How many of the following interactions does CH3CH2OH exhibit? London dispersion dipole-dipole hydrogen bonding A) 0 B) 1 C) 2 D) 3

Clicker Question How many of the following interactions does CH3OCH3 exhibit? London dispersion dipole-dipole hydrogen bonding A) 0 B) 1 C) 2 D) 3

Clicker Question Rank the molecules with respect to boiling point. A) CH3CH2CH3 > CH3OCH3 > CH3CH2OH B) CH3CH2CH3 > CH3CH2OH > CH3OCH3 C) CH3CH2OH > CH3CH2CH3 > CH3OCH3 D) CH3CH2OH > CH3OCH3 > CH3CH2CH3

Ion-ion interactions Ionic compounds exhibit these forces. Due to ions. Strongest of the IMFs (given similar sized molecules). Example includes sodium chloride (NaCl).