e2f08 - Version PREVIEW Exam 2 JOHNSON (53755) 1 This...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Version PREVIEW Exam 2 JOHNSON (53755) 1 This print-out should have 30 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. LDE Ranking Bonding Trends 004 001 10.0 points The following molecules are composed of hy- drogen(s) bound to another atom, X. Rank the HX bonds in terms of decreasing polar- ity: LiH , NH 3 , BH 3 , HF. 1. LiH > NH 3 > BH 3 > HF 2. NH 3 > BH 3 > HF > LiH 3. HF > LiH > NH 3 > BH 3 correct 4. NH 3 > HF > BH 3 > LiH 5. BH 3 > HF > LiH > NH 3 Explanation: Note that all of the bonds within both NH 3 , BH 3 are identical to each other and the fact that there are multiple bonds does not change the polarity of the individual bonds. The EN for LiH , NH 3 , BH 3 , HF are 1.2, 0.8, 0.2, 1.8, respectively. Arranged from greatest to least: HF > LiH > NH 3 > BH 3 . LDE Identifying Bonds 002 002 10.0 points Which of the following exhibits non-polar bonds in a polar molecule? 1. O 3 correct 2. C 2 H 4 3. BI 3 4. CS 2 5. SiCl 4 Explanation: Ozone (O 3 ) is the only polar molecule composed of non-polar bonds. The other molecules are all symmetrical and therefore non-polar. LDE VSEPR Molecular Geometry 003 003 10.0 points In a molecule of the form AB 2 U x where A is a central atom, B is a bonded atom, and U is an unbonded electron pair, what value of x would yield a non-polar molecule that is not hypervalent? 1. 2 2. correct 3. 4 4. 1 5. 3 Explanation: Having 2 identical bonded atoms and 0 non- bonding electrons would correspond to linear molecular geometry and be non-polar. Hav- ing 1 or 2 non-bonding electron pairs would correspond to angular molecular geometry and be polar. Having 3 or 4 non-bonding electron pairs would be hypervalent. LDE VSEPR Molecular Geometry 004 004 10.0 points Which one of the compounds listed below is NOT expected to exhibit bond angles dis- torted from expected VSEPR values by un- bonded electron pairs? 1. SCl 4 2. NH 3 3. O 3 4. H 2 O 5. I 3 correct Explanation: All of the choices except I 3 have asymmet- rically placed non-bonding electron pairs on their central atoms and thus have distorted Version PREVIEW Exam 2 JOHNSON (53755) 2 bond angle. I 3 has three non-bonding elec- tron pairs in equatorial positions and thus has a single bond angle of exactly 180 . LDE VB Hybridization 003 005 10.0 points Which of the following statements concerning valence bond theory is/are true? I) Hybridizing one 2 s orbital with three 2 p orbitals would produce four sp 3 orbitals. II) When a 2 s orbital is hybridized with a single 2 p orbital, there will be a single unhybridized 2 p orbital left to form a bond with. III) Among the types of hybrid orbitals we have learned about, the minimum amount of s-character for a hybrid or- bital is 1/6 th ....
View Full Document

This note was uploaded on 03/04/2011 for the course CH 302 taught by Professor Holcombe during the Spring '07 term at University of Texas at Austin.

Page1 / 8

e2f08 - Version PREVIEW Exam 2 JOHNSON (53755) 1 This...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online