UNE - Chem 1011 - Midterm Study Guide
A hydrogen bond is characterized by
A. the attraction of temporary dipoles produced by the random asymmetries in electron motion
B. the electrostatic attraction between the permanent dipoles in any polar molecule
C. the highly concentrated partial charge between an H atom and F, O, or N atoms
D. the covalent sharing of electrons between two atoms in a molecule
C. the highly concentrated partial charge between an H atom and F, O, or N atoms
(Ref: Week 1 Quiz)
A. LDF's
B. Dipole-Dipole
D. Covalent Bond
We have an expert-written solution to this problem!
Which of the following will have the strongest dipole-dipole attractions?
A. NCl3
B. CCl4
C. BCl3
D. Cl2
A. NCl3
(Ref: Week 1 Quiz)
Asymmetrical - Usually have a higher dipole moment
Why not BCl3? Because Nitrogen is more electronegative than Boron.
,A cohesive force
A. is the result of the intermolecular forces that attract identical molecules
B. is the result of the intermolecular forces that attract different molecules together
C. is the result of covalent interactions between atoms in a molecule
D. is always stronger than an adhesive force
A. is the result of the intermolecular forces that attract identical molecules
(Ref: Week 1 Quiz)
Easy way to remember. Co = mutual so cohesive is identical molecules.
ΔHvap is
A. the energy change when a substance changes from the liquid phase to the gas phase
B. the energy change when a substance changes from the solid phase to the liquid phase
C. the energy change when a substance changes from the liquid phase to the solid phase
D. the energy change when a substance changes from the solid phase directly to the gas phase
A. the energy change when a substance changes from the liquid phase to the gas phase
(Ref: Week 1 Quiz)
Liquid → Gas (Vaporization)
Ex: Boiling
A liquid in a tube will form a convex meniscus when
A. the adhesive forces are stronger than the cohesive forces
, B. the cohesive forces are stronger than the adhesive forces
C. the adhesive forces are equal to the cohesive forces
D. it's impossible to predict
B. the cohesive forces are stronger than the adhesive forces.
(Ref: Week 1 Quiz)
In a phase diagram, the critical pressure represents
A. the temperature and pressure when gas, liquid, and solid phases coexist
B. the maximum temperature that a liquid can exist
C. the maximum pressure that a gas can exist
D. the minimum pressure that a solid can exist, regardless of temperature
C. the maximum pressure that a gas can exist
(Ref: Quiz Week 1)
Key word: pressure, so the answer is either C or D. We know it isn't D because the critical point
of a phase diagram exists near the supercritical fluid area.
Molecular solids
A. are composed of positive and negative ions held together by electrostatic attractions
B. are composed of atoms, with nuclei in a "sea" of delocalized electrons
C. are composed of atoms held together by a repeating network of covalent bonds
D. are composed of neutral molecules held together by intermolecular forces
D. are composed of neutral molecules held together by intermolecular forces
A hydrogen bond is characterized by
A. the attraction of temporary dipoles produced by the random asymmetries in electron motion
B. the electrostatic attraction between the permanent dipoles in any polar molecule
C. the highly concentrated partial charge between an H atom and F, O, or N atoms
D. the covalent sharing of electrons between two atoms in a molecule
C. the highly concentrated partial charge between an H atom and F, O, or N atoms
(Ref: Week 1 Quiz)
A. LDF's
B. Dipole-Dipole
D. Covalent Bond
We have an expert-written solution to this problem!
Which of the following will have the strongest dipole-dipole attractions?
A. NCl3
B. CCl4
C. BCl3
D. Cl2
A. NCl3
(Ref: Week 1 Quiz)
Asymmetrical - Usually have a higher dipole moment
Why not BCl3? Because Nitrogen is more electronegative than Boron.
,A cohesive force
A. is the result of the intermolecular forces that attract identical molecules
B. is the result of the intermolecular forces that attract different molecules together
C. is the result of covalent interactions between atoms in a molecule
D. is always stronger than an adhesive force
A. is the result of the intermolecular forces that attract identical molecules
(Ref: Week 1 Quiz)
Easy way to remember. Co = mutual so cohesive is identical molecules.
ΔHvap is
A. the energy change when a substance changes from the liquid phase to the gas phase
B. the energy change when a substance changes from the solid phase to the liquid phase
C. the energy change when a substance changes from the liquid phase to the solid phase
D. the energy change when a substance changes from the solid phase directly to the gas phase
A. the energy change when a substance changes from the liquid phase to the gas phase
(Ref: Week 1 Quiz)
Liquid → Gas (Vaporization)
Ex: Boiling
A liquid in a tube will form a convex meniscus when
A. the adhesive forces are stronger than the cohesive forces
, B. the cohesive forces are stronger than the adhesive forces
C. the adhesive forces are equal to the cohesive forces
D. it's impossible to predict
B. the cohesive forces are stronger than the adhesive forces.
(Ref: Week 1 Quiz)
In a phase diagram, the critical pressure represents
A. the temperature and pressure when gas, liquid, and solid phases coexist
B. the maximum temperature that a liquid can exist
C. the maximum pressure that a gas can exist
D. the minimum pressure that a solid can exist, regardless of temperature
C. the maximum pressure that a gas can exist
(Ref: Quiz Week 1)
Key word: pressure, so the answer is either C or D. We know it isn't D because the critical point
of a phase diagram exists near the supercritical fluid area.
Molecular solids
A. are composed of positive and negative ions held together by electrostatic attractions
B. are composed of atoms, with nuclei in a "sea" of delocalized electrons
C. are composed of atoms held together by a repeating network of covalent bonds
D. are composed of neutral molecules held together by intermolecular forces
D. are composed of neutral molecules held together by intermolecular forces
