CEM 142 UPDATED 2026 EXAM SCRIPT QUESTIONS AND
SOLUTIONS SCORED A+
✔✔Process of solution making - ✔✔solvent -solvent and solute -solute intermolecular
attractions that needs to be broken down.
Solute-solute needs to break IMFs.
Solvent-solute forms IMFs, if they are strong (=exothermic) if they are weak
(=endothermic)
✔✔How to estimate the relative solubilities of a range of given compounds? - ✔✔1.
Possible bonds formation 2.
✔✔Explain why non-polar molecules are not soluble in water. - ✔✔1. Non-polar
molecules does not dissolve in water because water would give up on strong IMF's
between them to form LDFs
2. The water molecules create HBs around the Non-polar molecules, creating a cage
that causes molecules to be imobile; thus, decreases the entropy
✔✔Discuss how large molecules with both polar and non-polar "parts" behave. Include
the role of the hydrophobic effect on micelle and bilayer formation. - ✔✔Large non-polar
molecules stick together into patters (micelle / bilayer) where the hydrophobic parts
interact the least possible with the polar molecules
Polar molecules interact with other molecules
✔✔Predict and explain the effect of temperature on the solubility of solid, liquid, and
gaseous solutes. - ✔✔Liquid/Solid - higher temperature normally increases solubility
Gas - increase temperature decreases solubility because it is more free in gaseous form
so decrease temperature makes it more soluble.
✔✔Explain how different inclusions in metals can alter the properties of the metal. For
example, consider steel, brass, or bronze. - ✔✔Ions can go in between of metals -
makes it stronger, denser (steal)
Ions can rearrange by substituting making it stronger metallic bonds (bronze)
✔✔7. Explain, using a molecular level explanation, the difference between a chemical
change and a phase change. Give an Example. - ✔✔A phase change does not alters
the bonds of molecules just the intermolecular forces that holds them together (Water
liquid --> water solid - it is still water). A Chemical change alters the properties and
bonds by rearranging matter.
, ✔✔Identify the molecular structural features that lead to acidic and basic properties in a
molecule. Why is it important? - ✔✔1- Bond strength: stronger the bond between H-A
harder it is to break, so weaker acid. Strong bonds are defined by similar
electronegativity properties and radius.
2- Stability of the conjugate base / acid: more stable the conjugate acid, stronger the
base.
3- Inductive effect: other atoms in the molecule can alter the electron distribution (HOCl)
Important to determine how the molecule will react.
✔✔What are some common strong and weak acids? - ✔✔Strong acids- HCl, HBr, HI,
HNO3, H2SO4
Weak- HF, CH3COOH, HCN
✔✔What are some common strong and weak bases? - ✔✔Strong bases- group I or II
metals with hydroxide (NaOH, KOH)
Weak- NH3, CH3NH2
✔✔What is the difference between strong, weak, diluted, and concentrated? -
✔✔Strong and weak are referring to the ionization of the molecule, while diluted and
concentrated is referring to the number of molecules in solution.
✔✔Predict and explain relative strengths of a range of related acids (bases) using
thermodynamic or electronegativity arguments. - ✔✔Strong Acids - high
electronegativity, high thermodynamics due to big radius (down periodic table so it does
not overlap orbitals)
Basic - less electronegative, lone pairs
✔✔Explain how the progression of Arrhenius, Bronsted Lowry, and Lewis acid-base
theories build on each other. - ✔✔Arrhenius: The neutralization reaction where an acid
reacts with a base to form a salt and water
Bronsted: when acids H+ are able to donate a proton to a base, that can receive it.
Lewis: the bases actually that start the reaction by having electrons that can be donated
to an acid that is electron needed (electrophile)
✔✔Predict the products of acid base reactions based on the relative strengths of the
acids and bases (put examples) - ✔✔
✔✔What determined an extent of an acid-base reaction? - ✔✔1- The number of
reactants / products.
2- The sign of ΔG
3- The equilibrium constant
SOLUTIONS SCORED A+
✔✔Process of solution making - ✔✔solvent -solvent and solute -solute intermolecular
attractions that needs to be broken down.
Solute-solute needs to break IMFs.
Solvent-solute forms IMFs, if they are strong (=exothermic) if they are weak
(=endothermic)
✔✔How to estimate the relative solubilities of a range of given compounds? - ✔✔1.
Possible bonds formation 2.
✔✔Explain why non-polar molecules are not soluble in water. - ✔✔1. Non-polar
molecules does not dissolve in water because water would give up on strong IMF's
between them to form LDFs
2. The water molecules create HBs around the Non-polar molecules, creating a cage
that causes molecules to be imobile; thus, decreases the entropy
✔✔Discuss how large molecules with both polar and non-polar "parts" behave. Include
the role of the hydrophobic effect on micelle and bilayer formation. - ✔✔Large non-polar
molecules stick together into patters (micelle / bilayer) where the hydrophobic parts
interact the least possible with the polar molecules
Polar molecules interact with other molecules
✔✔Predict and explain the effect of temperature on the solubility of solid, liquid, and
gaseous solutes. - ✔✔Liquid/Solid - higher temperature normally increases solubility
Gas - increase temperature decreases solubility because it is more free in gaseous form
so decrease temperature makes it more soluble.
✔✔Explain how different inclusions in metals can alter the properties of the metal. For
example, consider steel, brass, or bronze. - ✔✔Ions can go in between of metals -
makes it stronger, denser (steal)
Ions can rearrange by substituting making it stronger metallic bonds (bronze)
✔✔7. Explain, using a molecular level explanation, the difference between a chemical
change and a phase change. Give an Example. - ✔✔A phase change does not alters
the bonds of molecules just the intermolecular forces that holds them together (Water
liquid --> water solid - it is still water). A Chemical change alters the properties and
bonds by rearranging matter.
, ✔✔Identify the molecular structural features that lead to acidic and basic properties in a
molecule. Why is it important? - ✔✔1- Bond strength: stronger the bond between H-A
harder it is to break, so weaker acid. Strong bonds are defined by similar
electronegativity properties and radius.
2- Stability of the conjugate base / acid: more stable the conjugate acid, stronger the
base.
3- Inductive effect: other atoms in the molecule can alter the electron distribution (HOCl)
Important to determine how the molecule will react.
✔✔What are some common strong and weak acids? - ✔✔Strong acids- HCl, HBr, HI,
HNO3, H2SO4
Weak- HF, CH3COOH, HCN
✔✔What are some common strong and weak bases? - ✔✔Strong bases- group I or II
metals with hydroxide (NaOH, KOH)
Weak- NH3, CH3NH2
✔✔What is the difference between strong, weak, diluted, and concentrated? -
✔✔Strong and weak are referring to the ionization of the molecule, while diluted and
concentrated is referring to the number of molecules in solution.
✔✔Predict and explain relative strengths of a range of related acids (bases) using
thermodynamic or electronegativity arguments. - ✔✔Strong Acids - high
electronegativity, high thermodynamics due to big radius (down periodic table so it does
not overlap orbitals)
Basic - less electronegative, lone pairs
✔✔Explain how the progression of Arrhenius, Bronsted Lowry, and Lewis acid-base
theories build on each other. - ✔✔Arrhenius: The neutralization reaction where an acid
reacts with a base to form a salt and water
Bronsted: when acids H+ are able to donate a proton to a base, that can receive it.
Lewis: the bases actually that start the reaction by having electrons that can be donated
to an acid that is electron needed (electrophile)
✔✔Predict the products of acid base reactions based on the relative strengths of the
acids and bases (put examples) - ✔✔
✔✔What determined an extent of an acid-base reaction? - ✔✔1- The number of
reactants / products.
2- The sign of ΔG
3- The equilibrium constant
