MSEN 250 EXAM 1 UPDATED ACTUAL QUESTIONS AND
CORRECT ANSWERS
Question:
1. What is Gibbs free energy equation? When is an assembly favorable (in other words, self-assembly)?
Answer:
> ■ G = ■ H - T ■ S > When ■ G is (-)
Question:
2. What is the difference between crystalline solids and liquids in terms of structure and bonding? How
does soft matter act?
Answer:
Crystalline solids are locked in place w/ intermolecular interactions (stiff bc of this)...liquids are held with
intermolecular forces but constantly change the molecules that they are interacting w/ Soft matter acts like
both (liquid ordering and solid stiffness)
Question:
3. What are the two overarching types of interactions (think types of bonds)?
Answer:
Intramolecular (between the molecule itself) and intermolecular (between two molecules)
Question:
4. What are the main types of bonds/interactions (list in order of decreasing strength...strong
--> weak)
Answer:
metallic (not for soft matter), covalent, ionic, hydrogen bond, van der Waals
Question:
5. List *all* bonds/interactions w/ short definition.
Answer:
*Covalent bond*- sharing electrons, directional (can be evenly shared or polar and unevenly shared)
*Ionic bond*- atoms w/ electrostatic attraction (difficult to form in solution) *van der Waals*- general
intermolecular forces *hydrogen bonding*- occurs with O-H or N-H bonds *hydrophobic interactions*-
need a chain of C-H s w/out a polar functional group *dipole-dipole*- carbon bonds w/out hydrogen (C-O,
C-N, C-Cl, C-S...) *ion-dipole* (Ex: Na+ & H-O-H) *dipole-induced dipole* (a non-polar molecule
becomes so)
Question:
6. Between the two pairs, which is the most polar?
1) Li-F & Li-Cl
2) C=O & C=S
3) P-P & Si-O
, Answer:
1) Li-F
2) C=O
3) Si-O
Question:
7. What is the critical point (definition in terms of a phase diagram)?
Answer:
The end point of a phase diagram
Question:
8. What is the triple point (in terms of a phase diagram)?
Answer:
The point at which all three phases are present
Question:
9. Is deposition endothermic or exothermic?
Answer:
Exothermic-heat is being removed (L-->S)
Question:
10. When labeling a polar molecule in terms of polarity, how should the arrow be pointing?
Answer:
Towards the more polar atom
Question:
11. In terms of tensile, what is the equation for stress and strain? How are shear stress and shear strain
related in a solid? In a liquid?
Answer:
σ=F/A (stress) ε= (∆l)/l (strain ?rate?) solid: σ=Ge (e=shear strain, G=shear modulus) liquid: σ=ηε
(η=viscosity, ε=strain rate)
CORRECT ANSWERS
Question:
1. What is Gibbs free energy equation? When is an assembly favorable (in other words, self-assembly)?
Answer:
> ■ G = ■ H - T ■ S > When ■ G is (-)
Question:
2. What is the difference between crystalline solids and liquids in terms of structure and bonding? How
does soft matter act?
Answer:
Crystalline solids are locked in place w/ intermolecular interactions (stiff bc of this)...liquids are held with
intermolecular forces but constantly change the molecules that they are interacting w/ Soft matter acts like
both (liquid ordering and solid stiffness)
Question:
3. What are the two overarching types of interactions (think types of bonds)?
Answer:
Intramolecular (between the molecule itself) and intermolecular (between two molecules)
Question:
4. What are the main types of bonds/interactions (list in order of decreasing strength...strong
--> weak)
Answer:
metallic (not for soft matter), covalent, ionic, hydrogen bond, van der Waals
Question:
5. List *all* bonds/interactions w/ short definition.
Answer:
*Covalent bond*- sharing electrons, directional (can be evenly shared or polar and unevenly shared)
*Ionic bond*- atoms w/ electrostatic attraction (difficult to form in solution) *van der Waals*- general
intermolecular forces *hydrogen bonding*- occurs with O-H or N-H bonds *hydrophobic interactions*-
need a chain of C-H s w/out a polar functional group *dipole-dipole*- carbon bonds w/out hydrogen (C-O,
C-N, C-Cl, C-S...) *ion-dipole* (Ex: Na+ & H-O-H) *dipole-induced dipole* (a non-polar molecule
becomes so)
Question:
6. Between the two pairs, which is the most polar?
1) Li-F & Li-Cl
2) C=O & C=S
3) P-P & Si-O
, Answer:
1) Li-F
2) C=O
3) Si-O
Question:
7. What is the critical point (definition in terms of a phase diagram)?
Answer:
The end point of a phase diagram
Question:
8. What is the triple point (in terms of a phase diagram)?
Answer:
The point at which all three phases are present
Question:
9. Is deposition endothermic or exothermic?
Answer:
Exothermic-heat is being removed (L-->S)
Question:
10. When labeling a polar molecule in terms of polarity, how should the arrow be pointing?
Answer:
Towards the more polar atom
Question:
11. In terms of tensile, what is the equation for stress and strain? How are shear stress and shear strain
related in a solid? In a liquid?
Answer:
σ=F/A (stress) ε= (∆l)/l (strain ?rate?) solid: σ=Ge (e=shear strain, G=shear modulus) liquid: σ=ηε
(η=viscosity, ε=strain rate)
