Chapter 12 Notes Test Questions – Flashcards
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Unlock answers| What are the Strong IMF's? |
| high boiling point, high melting point, high ;Hvap, high ;Hfus, high ;Hsub, low VP |
| What are the weak IMF's? |
| low boiling point, low melting point, low ΔHvap , low ΔHfus, low ΔHsub, high VP |
| what is a dipole-dipole force? |
| a positive and a negative end of another molecule are attracted to each other |
which of the following molecules have dipole-dipole forces? a) CO2 b) CH2Cl2 c) CH4 d) Cl4 e) CH3Cl f) HCl |
a) CO2 no b) CH2Cl2 yes c) CH4 no d) Cl4 no e) CH3Cl yes f) HCl yes |
| what is an ion-dipole force? |
| the attractive forces between an ion and a polar molecule |
| Which should have more negative hydration energy, Cl- or Br-? |
| Br- is larger than Cl- so Cl- has the more negative ΔH hydration |
| what is a London Dispersion force? |
| present in all molecules |
what type(s) of intermolecular forces exist between each of the following molecules? a) HBr b) CCl4 c) PF3 d) PCl5 e) SO2 f) CS2 g) H2S |
a) HBr = dispersion forces, dipole-dipole forces b) CCl4 = dispersion forces c) PF3 = dispersion forces, dipole-dipole forces d) PCl5 = dispersion forces e) SO2 = dispersion forces, dipole-dipole forces f) CS2 = dispersion forces g) H2S = dispersion forces, dipole-dipole forces |
| what is a hydrogen bod? |
| a dipole-dipole interaction between the hydrogen atom in a polar N-H, O-H, or F-H bond and an electronegative O,N, or F atom |
Which of the following exhibits significant hydrogen bonding? a) HBr b) H2CF2 c) H2 d) CH3CN e) CCl4 f) CH3CO2H g) CH3COCH3 h) H2S i) CH3CH2OH |
a) HBr = no b) H2CF2 = no c) H2 = no d) CH3CN = no e) CCl4 = no f) CH3CO2H = yes g) CH3COCH3 = no h) H2S = no i) CH3CH2OH = yes |
| what is vapor pressure? |
| the pressure of a vapor above a liquid at a given temperature |
| what is vaporization? |
| the phase change from liquid to vapor |
| what is condensation? |
| the phase change from vapor to liquid |
| The molar enthalpy of vaporization of water is 40.7 kJ/mol at 100oC. How much energy is required to vaporize 925g of water at 100oC? (H2O = 18.02g/mol) |
g --> mol --> kJ 925g x (1mol H2O/18.02g) x (40.7kJ/1mol H2O) = 2.09 x 103kJ |
| Calculate the mass of water that can be vaporized at its boiling point with 155kJ of heat. (ΔHvap = 40.7kJ/mol) |
kJ --> mol --> g 155kJ x (1mol H2O/40.7kJ) x (18.02g/1mol) = 68.6g H2O |
| what is the Clausius-Clapeyron equation? |
ln (P2/P1) = - (ΔHvap/R)(1/T2 - 1/T1)
R = gas constant (8.314 J/K mol) |
The vapor pressure of benzene C6H6, is 40.1mmHg at 7.6oC. What is the vapor pressure at 60.6oC? (ΔHvap = 31.0kJ/mol) |
ln (P2/P1) = - (ΔHvap/R)(1/T2 - 1/T1) ln (P2/40.1mmHg) = - (31.0kJ/mol/8.314x10-3kJ/K mol)(1/333.6K - 1/218.6K) ln (P2/40.1mmHg) = 2.11 (take the antilog of both sides) P2/40.1mmHg = e2.11 P2 = e2.11 x 40.1mmHg P2 = 331mmHg |
