EMISTRY 110 EXAM 2 Oct. 11, 2010 FORM A --------------------------------------------------------------------------------- 1. What is the empirical formula that corresponds to a compound that contains only 57.69% carbon, 30.77% oxygen, and 11.54% hydrogen? A. 5 12 O 2 B. 2.5 6 O. 3 12 O 2 D. 58 12 O 31 E. 6 O 3 --------------------------------------------------------------------------------- 2. What is the weight percentage of nitrogen in urea [( 2 ) 2 O]? A. 46.7% B. 31.8%. 23.3% D. 48.3% E. 63.6% 3. To which class of compounds does the molecule shown below belong? A. alcohols B. aromatics. alkanes D. alkenes E. alkynes 4. What is the electron domain geometry of the [TeF 5 ] anion? A. octahedral B. trigonal bipyramidal. square planar D. seesaw E. square pyramidal ---------------------------------------------------------------------------------
5. A hydrocarbon consists of 85.7% by mass. It has one double bond and it is not heavier than oxygen [O 2 ]. What is the molecular formula of that hydrocarbon? A. 2 B. 2 2. 2 4 D. 2 6 E. 3 6 7. Which of the following organic molecules have the same empirical formula as cyclohexane? cyclohexane A B D E 8. Which of the following molecules is a carboxylic acid? 6. Which molecule or molecules has free rotation about the bond between the carbon atoms? A. i only B. ii only. iii only D. ii and iii only E. i, ii, and iii i. 2 6 ii. 2 4 iii. 2 2 O O O O O A B D E 9. Which one of the following molecules has square planar molecular geometry? A. l 4 B. XeF 4. P 3 D. XeF 2 E. SF 4
10. Arrange the following in order of increasing bond length. 1. 2 2 2. 2 6 3. 2 4 4. 6 6 " A. 2 < 3 < 4 < 1 B. 1 < 4 = 3 < 2. 1 < 4 < 3 < 2 D. 2 < 3 < 1 < 4 E. 1 < 3 < 4 < 2 12. For the following three species, order their ## bond angles from the smallest to the largest. 2 3 4 amid ammonia ammonium A. 3 < 2 < 4 B. 4 < 3 < 2. 3 < 4 < 2 D. 2 < 3 < 4 E. 2 < 4 < 3 13. Which of the following molecules has a non-zero net dipole moment? 11. Which of these statements are true for a typical double bond? i. A double bond between two atoms is stronger and shorter than a single bond between the same two atoms. ii. A double bond consists of one bond and one " bond. iii. There is no free rotation about a double bond. A. i only B. i and ii. ii and iii D. i and iii E. All of the above statements are true. A. BF 3 B. O 2. S 2 D. 3 O E. PF 5 14. Which substance has OLY London dispersion forces as an intermolecular force? A. al 2 B. Br. 3 3 D. 3 OO E. 3 Go on to the next page
--------------------------------------------------------------------------------- 15. ow many atoms are in a 31.6 g sample of ammonium nitrate? A. 1.21 $ 10 24 atoms B. 1.75 $ 10 24 atoms. 2.14 $ 10 24 atoms D. 2.38 $ 10 23 atoms E. 2.67 $ 10 24 atoms 16. What are the hybridizations of carbons labeled 1 and 2 in a caffeine molecule (shown below)? O O 1 ybridization of carbon 1 carbon 2 A. sp 2 sp 2 B. sp 3 d 2 sp 3. sp 2 sp 3 D. sp 3 sp 2 E. sp 3 sp 3 2 17. ow many % and & bonds are in acetonitrile, 3? A. 3 % and 3 & bonds B. 4 % and 2 & bonds. 4 % and 3 & bonds D. 5 % and 3 & bonds E. 5 % and 2 & bonds 18. Which of the following species exhibits delocalized bonding? A. 2 O B. O 2. 2 2 D. 3 = 2 E. 3 2 3 19. Liquid methanol ( 3 O) evaporates quickly at room temperature. To convert methanol from a liquid to a gas, which intermolecular interactions must be overcome? A. London dispersion forces only B. London dispersion forces and dipole-dipole forces. London dispersion forces, dipole-dipole forces, and hydrogen bonding D. London dispersion forces and ion-dipole forces E. ydrogen bonding only Go on to the next page
20. Glucose, 6 12 O 6 is a simple carbohydrate. Which statement is correct? 22. Which one of the following molecules is the geometrical isomer of cis-3,4-dimethyl-3-hexene shown below? A. A mole of glucose has larger mass, but fewer molecules than a mole of water ( 2 O). B. A mole of water has equal mass to a mole of glucose.. A mole of glucose has 6 times as many oxygen atoms as a mole of water. D. The mass of a mole of glucose is 6 times larger than the mass of a mole of water. E. A mole of water has the same number of hydrogen atoms as a mole of glucose. A B 21. A compound made up of only iodine and chlorine contains 45.59% chlorine by mass. Assuming that the empirical formula equals the molecular formula of this compound, what is the hybridization of the central atom of this compound? A. sp B. sp 2. sp 3 D. sp 3 d E. sp 3 d 2 E D --------------------------------------------------------------------------------- Go on to the next page
23. Which approximate ## and ## bond angles describe the structure of 3 2 2, the best? ## ## A. 109.5 o 120 o B. 109.5 o < 109.5 o. 120 o 109.5 o D. 120 o < 109.5 o E. < 109.5 o 109.5 o 24. onsider the neutral molecule with the molecular formula lof 3. hlorine is the central atom and the remaining four atoms are directly bonded to l. One of the F#l#F angles in this molecule is 175 (i.e. approximately 180 ). Based on this information, select the incorrect statement from the choices below. A. The molecular geometry of lof 3 is best described as approximately square planar. B. lof 3 has one non-bonding electron pair on l.. The three O#l#F angles in this molecule are approximately 90, 90, and 120. D. The hybridization of the l atom is sp 3 d. E. Every Lewis structure that can be drawn for lof 3 violates the octet rule. - 25. Which statement about the following molecule is false? F A. The hybridization of both of the carbon atoms is sp 2. B. The molecule shown above has 5 % bonds and 1 & bond.. The F## bond is less than 120. D. The molecule shown above does OT have a net dipole moment. E. The structure shown below is a geometrical isomer of the molecule above. 26. A 0.1014 g sample of purified fructose (which contains only, and O) was combusted to produce 0.1486 g of O 2 and 0.0609 g of 2 O. What was the mass of oxygen in the fructose sample? A. 0.0068 g B. 0.0406 g. 0.0540 g D. 0.0812 g E. 0.5320 g F F F Go on to the last page
27. Tetrahydrocannabinol (T) is the main psychoactive component of the cannabis plant. Its structure is shown below. Which of the following statements is false. 28. Which of the following molecular geometries cannot be observed in a molecule, for which the central atom is sp 3 d hybridized? E D O A O B trigonal planar linear T-shape seesaw trigonal bipyramidal A B D E A. The angle labeled A is approximately 109.5. B. The angle labeled B is 120.. The oxygen atom labeled is sp hybridized. D. The carbon atom labeled D is sp 2 hybridized. E. The carbon atom labeled E is sp 3 hybridized. ED OF EXAM
FORM A 1. A 2. A 3. E 4. A 5. 6. A 7. A 8. A 9. B 10. E 11. E 12. D 13. D 14. 15. 16. A 17. E 18. B 19. 20. 21. D 22. E 23. E 24. A 25. E 26. 27. 28. A EMISTRY 110 EXAM 2 OTOBER 11, 2010 Answer Key