CHEM 1160 Exam 3 Study Guide (copy)

What is the trend for acid strength across a period in the periodic table?

Acid strength increases with electronegativity.

Provide an example showing acid strength across a period.

HF > H₂O > NH₃ > CH₄.

What is the trend for acid strength down a group in the periodic table?

Acid strength increases with the size of the atom.

Provide an example showing acid strength down a group.

HI > HBr > HCl > HF.

What affects acid strength in terms of enthalpy?

Larger atoms have weaker H–X bonds, making them easier to break.

How does entropy relate to acid strength?

Larger ions disrupt fewer water molecules, increasing disorder which is favorable.

How does resonance affect acid strength?

More resonance in the conjugate base makes it more stable, leading to a stronger acid.

List the strong acids that one should know.

HCl, HBr, HI, HNO₃, HClO₄, H₂SO₄.

What is the relationship between Ka and acid strength?

A large Ka indicates a strong acid.

What is the formula for calculating pH?

pH = -log[H₃O⁺].

How do you calculate the concentration of hydronium ions from pH?

[H₃O⁺] = 10^(-pH).

What does Kw represent, and what is its value?

Kw = [H₃O⁺] * [OH⁻] = 1 x 10^{-14}.

How do you calculate percent ionization of an acid?

% = ([H₃O⁺] / [acid initial]) * 100.

Differentiate between strong and weak acids/bases in terms of ionization.

Strong acids/bases completely ionize; weak acids/bases partially ionize.

What is oxidation in redox reactions?

Loss of electrons.

What is reduction in redox reactions?

Gain of electrons.

How do you assign oxidation states to free elements?

Free elements have an oxidation state of 0.

What is the general form of a rate law for a reaction?

Rate = k[A]^m[B]^n.

How do you find the units of k in a rate law?

Units depend on the overall reaction order.

What is the activation energy (Ea)?

Energy needed to start a reaction.

What do exothermic reactions produce in terms of enthalpy?

ΔH < 0.

What do endothermic reactions produce in terms of enthalpy?

ΔH > 0.

What is the relationship of ΔG to ΔH and ΔS?

ΔG = ΔH - TΔS.

What does it mean when ΔG = 0?

The system is at equilibrium.

What does K > 1 indicate about a reaction?

The reaction favors products.

What does Le Châtelier’s Principle state about changing reactant concentration?

Adding reactants shifts the equilibrium to the right.

How does increasing pressure affect equilibrium?

Shifts the equilibrium to the side with fewer gas moles.

What is the effect of temperature on exothermic reactions according to Le Châtelier’s Principle?

Increasing temperature shifts equilibrium to the left.

Do catalysts affect the position of equilibrium?

No, catalysts only speed up the rate of reaching equilibrium.

What is the impact of hybridization on acid strength?

Higher hybridization (more s-character) leads to stronger acids due to greater bond strength.

How does the presence of electronegative atoms affect acid strength?

Electronegative atoms stabilize the conjugate base, resulting in stronger acids.

What is the relationship between bond length and acid strength?

Longer bond lengths correspond to weaker bonds, making it easier to donate protons and resulting in stronger acids.

Explain how the size of a conjugate base impacts acid strength.

A larger conjugate base can spread charge over a larger volume, leading to increased stability and stronger acids.

What role does solvation play in acid strength?

Effective solvation stabilizes the conjugate base, enhancing acid strength.

What is the trend for strong bases in relation to the periodic table?

Strong bases tend to be found in Group 1 and Group 2 of the periodic table.

Can you give examples of weak acids?

Examples include acetic acid (CH₃COOH) and formic acid (HCOOH).

What defines a Lewis acid?

A Lewis acid is an electron pair acceptor.

What defines a Lewis base?

A Lewis base is an electron pair donor.

What is the significance of pKa in discussing acid strength?

A lower pKa value indicates a

What are the common properties of acids?

Acids typically taste sour, can conduct electricity, react with metals to produce hydrogen gas, and turn blue litmus paper red.

What is a buffer solution?

A buffer solution is a mixture that can resist changes in pH when small amounts of acid or base are added.

How does temperature affect the solubility of solids in liquids?

Generally, the solubility of solid substances in liquids increases with an increase in temperature.

What is the pH range for acidic solutions?

Acidic solutions have a pH range of 0 to less than 7.

What is the function of a titration in chemistry?

A titration is a technique used to determine the concentration of an unknown solution by reacting it with a solution of known concentration

What are the common properties of acids?

Acids typically taste sour, can conduct electricity, react with metals to produce hydrogen gas, and turn blue litmus paper red.

What is a buffer solution?

A buffer solution is a mixture that can resist changes in pH when small amounts of acid or base are added.

How does temperature affect the solubility of solids in liquids?

Generally, the solubility of solid substances in liquids increases with an increase in temperature.

What is the pH range for acidic solutions?

Acidic solutions have a pH range of 0 to less than 7.

What is the function of a titration in chemistry?

A titration is a technique used to determine the concentration of an unknown solution by reacting it with a solution of known concentration

What defines a Lewis acid?

A Lewis acid is an electron pair acceptor.

What defines a Lewis base?

A Lewis base is an electron pair donor.

What is the significance of pKa in discussing acid strength?

A lower pKa value indicates a stronger acid.

What is oxidation in redox reactions?

Loss of electrons.

What is reduction in redox reactions?

Gain of electrons.

What is the trend for acid strength across a period in the periodic table?

Acid strength increases with electronegativity.

What is the trend for acid strength down a group in the periodic table?

Acid strength increases with the size of the atom.