CHEM 0120 Lecture Notes - Lecture 1: Transition State Theory, Endothermic Process, Equilibrium Constant

59 views6 pages

rubyraven894

6 Feb 2017

School

Department

Course

Professor

For unlimited access to Class Notes, a Class+ subscription is required.

Document Summary

Ea(cid:272)h phase (cid:272)ha(cid:374)ge is a(cid:272)(cid:272)o(cid:373)pa(cid:374)ies (cid:271)(cid:455) a sta(cid:374)da(cid:396)d e(cid:374)thalp(cid:455) (cid:272)ha(cid:374)ge (cid:894) h(cid:895) Dynamic equilibrium: molecules are entering and leaving a phase at equal rates. To find heat of vaporization use the clasius-clape(cid:455)(cid:396)o(cid:374) (cid:894)(cid:396)elates te(cid:373)p a(cid:374)d vp(cid:895) h i(cid:374) joules. Boiling point is directly proportional to applied pressure. Temperature does not change during a phase change. Larger molecular weight = more imf = higher boiling point = higher pressure. Heat for phase (cid:272)ha(cid:374)ges: (cid:894) h (cid:454) (cid:374)(cid:895) + (cid:894)s (cid:454) (cid:373) (cid:454) t(cid:895) Phase diagrams give the conditions of temperature and pressure at which each phase is stable. Viscosity: resistance of a fluid to flow (decreases with heating and smaller molecules) Van der waals: the attraction of imf between molecules (exists in every molecule) Hydrogen: a dipole-dipole force that occurs when an h atom is bonded to n, o, or f. Ion-induced dipole: np and ion; dipole-induced dipole: np and polar. London-dispersion: only force that exists between non-polar molecules.

Related Questions

* Circle the intermolecular force(s) that is/are present in each of the following species. [Hint: there may be more than one correct answer.]

Ar (hydrogen bonding, dipole-dipole forces, dispersion forces)

CH4 (hydrogen bonding, dipole-dipole forces, dispersion forces)

HBr (hydrogen bonding, dipole-dipole forces, dispersion forces)

HF (hydrogen bonding, dipole-dipole forces, dispersion forces)

CHCl3 (hydrogen bonding, dipole-dipole forces, dispersion forces)

* For the following pairs of atoms/molecules, circle the species that has the higher boiling point.

Ne or Xe

Cl2 or F2

HBr or HF

HCl or HI

H2O or H2S

* Phase changes always associate with change of enthalpy. For the following situations, name the phase

transition and indicate whether the process is exothermic or endothermic.

(a) Dry ice (solid carbon dioxide) turns to gaseous carbon dioxide.

Answer:

(b) Water vapor turns to liquid water.

Answer:

(d) Iodine vapor turns to solid iodine.

Answer:

(e) Liquid helium turns to helium gas.

Answer:

* True or false

1. Intermolecular forces are stronger than ionic and covalent bonds. Answer:

2. For molecules with similar size and molar mass, those with higher polarity would have higher boiling

point. Answer:

3. Ion-dipole forces exist between ionic potassium bromide and polar water.

Answer:

4. Dispersion forces exist between argon and helium. Answer:

5. Instantaneous dipoles exist in all molecules and atoms. Answer:

6. The strength of dispersion forces depends on the molar mass but the shape of the molecules have no effect on dispersion forces. Answer:

7. Ice has a higher density than water because ice has an ordered cagelike structure. Answer:

8. Liquids with weaker intermolecular interactions have lower viscosity. Answer:

9. Viscosity decreases with increasing temperature. Answer:

10. For any molecules, the heat of vaporization is always lower than the heat of fusion because it takes more energy to make molecules to move past one another in a solid lattice. Answer:

Phase changes always associate with change of enthalpy. For the following situations, name the phase transition and indicate whether the process is exothermic or endothermic.

. Dry ice (solid carbon dioxide) turns to gaseous carbon dioxide. Answer:

. Water vapor turns to liquid water. Answer:

. Solid iron turns to liquid iron. Answer:

. Iodine vapor turns to solid iodine. Answer:

. Liquid helium turns to helium gas. Answer:

True or false

. Intermolecular forces are stronger than ionic and covalent bonds. Answer:

. For molecules with similar size and molar mass, those with higher polarity would have higher boiling point. Answer:

. Ion-dipole forces exist between ionic potassium bromide and polar water. Answer:

. Dispersion forces exist between argon and helium. Answer:

. Instantaneous dipoles exist in all molecules and atoms. Answer:

. The strength of dispersion forces depends on the molar mass but the shape of the molecules have no effect on dispersion forces. Answer:

. Ice has a higher density than water because ice has an ordered cagelike structure. Answer:

. Liquids with weaker intermolecular interactions have lower viscosity. Answer:

. Viscosity decreases with increasing temperature. Answer:

. For any molecules, the heat of vaporization is always lower than the heat of fusion because it takes more energy to make molecules to move past one another in a solid lattice. Answer:

CHEM 0120 Lecture Notes - Lecture 1: Transition State Theory, Endothermic Process, Equilibrium Constant

Document Summary

Get access

Related textbook solutions

Chemistry: Structure and Properties

Basic Chemistry

Principles of Chemistry Molecular Approach

Principles of Chemistry Molecular Approach

Chemistry: Structure and Properties

Chemistry: A Molecular Approach

Chemistry: A Molecular Approach

Principles of Chemistry: A Molecular Approach

Chemistry: The Central Science

Related Documents

CHEM 1125Q Lecture Notes - Lecture 3: Zinc Sulfide, Covalent Bond, Coordination Number

CHM 142 Chapter Notes - Chapter 11: Lattice Energy, Ionic Radius, Ionic Compound

CHEM 1B Study Guide - Midterm Guide: Network Covalent Bonding, Coordination Number, Diamond Cubic

Related Questions