Question

CHEM 1414-1 Name: _______________________________ Chapter 13 Page 1 of 3 1) Circle which member in each pair has the larger dispersion forces? (a) CCl4 or CH4 (b) SO or SO2 (c) Br2 or HBr 2) Circle which member in each pair has the stronger intermolecular dispersion forces? (a) CO2 or CO (b) CH3Br or CH3Cl (c) CH3CH2CH2Cl or CH3CH2Cl 3) Identify the type or types of intermolecular forces present in each substance. (a) propane, C3H8 dispersion dipole-dipole hydrogen bonding ionic n-butane, C4H10 dispersion dipole-dipole hydrogen bonding ionic Circle the substance that has the higher boiling point. (b) hydrazine, NH2NH2 dispersion dipole-dipole hydrogen bonding ionic ethane, CH3CH3 dispersion dipole-dipole hydrogen bonding ionic Circle the substance that has the higher boiling point. (c) phosgene, Cl2CO dispersion dipole-dipole hydrogen bonding ionic formaldehyde, H2CO dispersion dipole-dipole hydrogen bonding ionic Circle the substance that has the higher boiling point. 4) What type of attraction does each liquid exhibit? (a) NCl3 (b) N2 (c) CO (d) HF 5) Within each group, assign each of the boiling points to the appropriate substance on the basis of intermolecular forces (a) Ne, Ar, Kr: –246 °C, –186 °C, –152 °C (b) NH3, H2O, HF: –33 °C, –20 °C, 100 °C 6) Name the phase transition in each of the following situations and indicate whether it is exothermic or endothermic: (a) Bromine vapor turns to bromine liquid as it is cooled. (b) Crystals of iodine disappear from an evaporating dish as they stand in a fume hood. (c) Rubbing alcohol in an open container slowly disappears. (d) Molten lava from a volcano turns into solid rock. 7) Calculate the amount of heat required to convert 65.0 g of ice at °-4 C to steam at 113. °C. 8) Which one of the following would have the highest molar heat of vaporization? a. CH3NH2 b. CH4 c. C2H6 d. SiH4 e. H2S 9) Using the Clausius-Clapeyron equation determine the vapor pressure of water at 50.0 C. The molar heat of vaporization of water is 40.7 kJ/mol. (Review Sample Exercise: Example 13-4) ln ( R = 8.314 J 10) Referring to the figure below, describe the phase changes (and the temperatures at which they occur) when CO2 is heated from −80 °C to 0 °C at: (a) a constant pressure of 1 atm (b) a constant pressure of 10 atm 11) As the intermolecular attractive forces between molecules increase in magnitude, do you expect each of the following to increase or decrease in magnitude? (a) heat of vaporization (b) vapor pressure (c) surface tension (d) critical temperature 12) Do Chapter 13 excercise #73 in the book. (a) (b) (c)

Answer 1

1) Circle which member in each pair has the larger dispersion forces?
Dispersion force depends on size of molecule. Greater the size of molecule, greater will be dispersion forces

(a) CCl4 or CH4
Answer : CCL4

(b) SO or SO2
Answer : SO2

(c) Br2 or HBr
Answer : Br2

2) Circle which member in each pair has the stronger intermolecular dispersion forces?
Dispersion force depends on size of molecule. Greater the size of molecule, greater will be dispersion forces

(a) CO2 or CO
Answer: CO2

(b) CH3Br or CH3Cl
Answer: CH3Br

(c) CH3CH2CH2Cl or CH3CH2Cl
Answer: CH3CH2CH2Cl

3) Identify the type or types of intermolecular forces present in each substance.

(a) propane, C3H8 : It is non polar So It has dispersion

C4H10 : : It is non polar So It has dispersion

(b) hydrazine, NH2NH2 : here H is attached to electronegative element N, So it will have Hydrogen bonding

ethane, CH3CH3 :: It is non polar So It has dispersion

(c) phosgene, Cl2CO :It is polar in nature So it has dipole-dipole
H2CO : :It is polar in nature So it has dipole-dipole

4) What type of attraction does each liquid exhibit?
(a) NCl3 ::It is polar in nature So it has dipole-dipole

(b) N2 : It is non polar So It has dispersion

(c) CO ::It is polar in nature So it has dipole-dipole

(d) HF ::It is polar in nature So it has dipole-dipole

I am allowed to answer only 1 question at a time. But I am answering 4 of them