Chemistry Unit 7

Arrhenius definition of acids and bases

Acid produces H⁺ (hydrogen ions) in water, Base produces OH⁻ (hydroxide ions) in water,

Brønsted-Lowry definition of acids and bases

Acid donates a proton (H⁺), base Accepts a proton (H⁺)

Arrhenius acid

Produces H⁺ in water

Brønsted-Lowry acid

Donates H⁺

Arrhenius base

Produces OH⁻ in water

Brønsted-Lowry base

Accepts H⁺

Solvent required by Arrhenius definition

Must be in water

Solvent allowed by Brønsted-Lowry definition

Any solvent or medium

Scope of Arrhenius definition

Narrow (only aqueous solutions)

Scope of Brønsted-Lowry definition

Broad (works in many contexts)

Formula for pH

pH = -log[H+]

Formula for pOH

pOH = -log[OH-]

How to find [H+] from pH

[H+] = 10^{-pH}

How to find [OH-] from pOH

[OH-] = 10^{-pOH}

Relationship between pH and pOH

pH + pOH = 14

Relationship between [H+] and [OH-]

[H^+] × [OH^-] = 1.0 × 10^{-14}

Solute

The substance that is dissolved in a solvent to form a solution (e.g., salt in saltwater).

Solvent

The substance that does the dissolving in a solution, usually present in greater amount (e.g., water in saltwater).

Acid

A substance that increases the concentration of hydrogen ions (H⁺) in an aqueous solution.

Base

A substance that increases the concentration of hydroxide ions (OH⁻) in an aqueous solution or accepts hydrogen ions.

Hydronium ion (H₃O⁺)

A water molecule that has accepted a proton (H⁺); the form in which hydrogen ions exist in water.

Strong acid

An acid that completely ionizes (dissociates) in solution, releasing all of its H⁺ ions.

Weak acid

An acid that only partially ionizes in solution, meaning only some molecules donate H⁺ ions. Ionized/Dissociated: Describes the process where molecules split into ions when dissolved in water (e.g., HCl → H⁺ + Cl⁻).

Diprotic acid

An acid that can donate two protons (H⁺ ions) per molecule (e.g., H₂SO₄).

Triprotic acid

An acid that can donate three protons (H⁺ ions) per molecule (e.g., H₃PO₄).

Amphoteric

A substance that can act as both an acid and a base, depending on the situation (e.g., water).

Molarity (M)

A measure of concentration; the number of moles of solute per liter of solution (mol/L).

Neutralization reaction

A chemical reaction between an acid and a base that produces water and a salt.

Dilution

The process of reducing the concentration of a solution by adding more solvent (usually water).

Saturated

A solution that contains the maximum amount of solute that can dissolve at a given temperature.

Polyatomic ions

Function as singular units and have charges

Process of balancing equations for neutralization reactions

Find Reactants and balance charges, Construct equation with water on product side, Fill in the blank with the missing Element and balance charges, and, finally, balance the equation.

Q: What is a neutralization reaction?

A chemical reaction between an acid and a base that produces water and a salt.

Q: How do you balance a neutralization reaction between a monoprotic acid and a base like Sr(OH)₂?

Use stoichiometry to balance H⁺ from the acid with OH⁻ from the base. Sr(OH)₂ has 2 OH⁻ ions, so it reacts with 2 moles of a monoprotic acid.

Q: What is the mole ratio in a balanced chemical equation used for?

It allows you to convert between moles of one substance and moles of another using coefficients in the balanced equation.

Q: What does molarity (M) represent?

Molarity = moles of solute ÷ liters of solution

Q: How do you find moles from molarity and volume?

Multiply molarity by volume in liters:
moles=M×L

Q: How do you find the volume of solution from moles and molarity?

Divide moles by molarity:
volume=molesM

Q: How do you find the mass of solute to make a solution?

Use molarity and volume to get moles, then:
mass=moles×molar mass

Q: What is the formula for dilution?

M1V1=M2V2, where M = molarity, V = volume

Q: What happens to concentration when water evaporates from a solution?

The concentration increases (same solute, less water = more concentrated)

Q: If you remove half the solution, what happens to the concentration?

The concentration stays the same (you're removing equal amounts of solute and solvent)

Q: What happens to concentration if you add more solute to the same volume?

The concentration increases

Q: How do you determine if a solution is acidic or basic using [H⁺] and [OH⁻]?

Use this rule:
If [H⁺] > [OH⁻], it’s acidic
If [OH⁻] > [H⁺], it’s basic

Q: What is the relationship between [H⁺] and [OH⁻] in water?

[H+]×[OH−]=1.0×10−14

Q: What is the equivalence point in a titration?

The point at which moles of acid = moles of base (reaction is exactly neutralized)

Q: How do you find the unknown concentration in a titration?

Use mole ratios and:
M1V1(acid)=M2V2(base) (if 1:1 ratio)
Adjust if not 1:1 based on balanced equation.

Q: What does phenolphthalein indicate?

It's colorless in acid and pink in base

Q: What is an electron configuration?

A way of showing where electrons are in an atom’s orbitals (e.g., 1s² 2s² 2p⁶…)

Q: What is a noble gas configuration?

A shorthand electron configuration using the previous noble gas in brackets, e.g. [Ne] 3s² 3p¹