Fall, 2013- Chemistry 2311 Homework Problems- Chapter 2 (1) Indicate True (T) or False (F) for each of the following statements: (a) Salicylic acid is an equilibrium mixture of two constitutional isomers. (b) Electronegativity is a measure of the ability of an element to attract shared electrons in a covalent bond. (c) All carbon-carbon bonds in benzene have bond lengths in between that of a single bond and a double bond. (d) A dipole moment is a vector; it has both magnitude and direction. (e) 1,1-Dichloroethene has a zero dipole moment. (f) The carbon bearing the hydroxyl group in isopropyl alcohol is a 3o carbon. (g) The melting point of a substance is the temperature at which equilibrium exists between the well-ordered crystalline state and the more random gaseous state. (h) Dipole-dipole forces are stronger than ion-ion forces. (i) A hydrogen bond is formed by hydrogen acting a bridge between two highly electronegative elements. (j) Polarizability is a measure of ease of response of electrons in an atom or molecule to a change in electric field.(k) The boiling point of a liquid is the temperature at which the vapor pressure of the liquid equals the pressure of the atmosphere above it. (l) Methanol (CH3OH) is more soluble in water than 1-pentanol (CH3CH2CH2CH2CH2OH) because the C5H11 unit attached to the OH in 1-pentanol is more hydrophilic than the CH3 unit in methanol. (m) The ammonia molecules has a tetrahedral shape. (n) Acetic acid is lower boiling than ethyl alcohol. (o) Hydrophobic means incompatible with water. (p) The frequency of a given stretching vibration in an IR spectrum can be related to (1) the masses of the bonded atoms, and (2) the relative stiffness of the bond. (q) In order for a vibration to occur with the adsorption of IR energy, the dipole moment of the molecule must change as the vibration occurs. (2) Draw structures for each of the following functional groups. Use the symbol “R” to designate alkyl or aryl groups. (a) a tertiary amine (3o amine) (b) an N,N-dialkyl amide (c) a secondary alcohol (2o alcohol) (d) an alkene(e) a nitrile (f) a dicarboxylic acid (g) an ether (3) Which of the following molecules will have the largest dipole moment? (a) (c) FCH3FH3C HCH2FFH2CH (b) (d) FCH3H3CF HCH3H3CH(4) Which of the following molecules has the highest boiling point? (a) (c) HCOCH3HH3C HCO2HHH3C (b) (d) HCH2OHHH3C HCO2CH3HH3C (5) Which of the following has the greatest solubility in water? (a) (c) O C2H5OH (b) (d) OHH O (6) What are the functional groups to which the arrows are pointing?OOOHOCOCH3NC (7) Associate each of the following infrared spectra (a-g) with one of the following structures by placing the name of the structure next to the infrared spectrum.(a)(b) (c )(d) (e)(f)
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