CHEMDUNN

This episode covers Le Chatelier's Principle, explaining how a chemical system at equilibrium will always shift its position to counteract and undo an external "stress." It explores three primary stressors: concentration changes, where the system shifts away from what is added and toward what is removed; pressure or volume changes, which force a shift toward the side with fewer gas m...

This episode breaks down the fundamentals of the pH scale, explaining its concept, mathematics, and real-world applications. It defines pH as the "power of hydrogen," a logarithmic measurement of hydrogen ion concentration ([H+]) where each unit represents a tenfold change in acidity or basicity. Through real-world examples ranging from battery acid to bleach, the episode demonstrates ho...

This episode introduce the Reaction Quotient (Q) and explain how it serves as a "GPS" to predict whether a chemical reaction will shift toward products or reactants to reach its destination, the Equilibrium Constant (K). While both share the identical mathematical expression of products over reactants raised to their coefficients, the episode highlights that K is a fixed constant at a sp...

This episode introduce the ICE table (Initial, Change, Equilibrium) as a foundational tool for tracking concentration changes and calculating the equilibrium constant (K) in chemical reactions. It explain how to construct the table by using initial concentrations, applying stoichiometry and a variable (x) to determine the change, and combining them to find the equilibrium values. The episode walks...

In this episode, we explore the fundamentals of differential rate laws — the mathematical expressions that describe how the speed of a chemical reaction depends on the concentration of its reactants. We break down the general rate law equation, Rate = k[A]^m[B]^n, explaining the role of the rate constant k , reaction orders, and how to calculate the overall reaction order. Through two fully worked...

This episode explores molecular polarity, explaining how electronegativity differences create polar bonds and why molecular geometry determines overall polarity. The hosts distinguish between bond polarity and molecular polarity, showing how symmetrical molecules like CO₂ and CH₄ are nonpolar despite polar bonds, while asymmetrical molecules like H₂O and NH₃ are polar. They conclude with a step-by...

Faraday's Law relates the amount of chemical change in an electrolytic cell to the total electric charge passed through it. The amount of product is directly proportional to the charge. Using Faraday's constant (96,485 C/mol/e-), the charge converts to moles of electrons, which then relates to moles of product via the half-reaction stoichiometry. This allows calculation of the mass of subs...

Electrolysis uses electrical energy to drive a nonspontaneous redox reaction, the opposite of a voltaic cell. An electrolytic cell requires a power source, where the anode is positive and the cathode is negative (reversed polarity from voltaic). The process is used to split molten salts or aqueous solutions. For aqueous solutions, water's reduction/oxidation potential must be considered, as it...

This episode explains how to calculate non-standard cell potentials (voltage) using the Nernst equation. Real-life batteries operate under non-standard conditions where concentrations change, causing voltage to drop. The equation shows that as the reaction quotient Q increases (more product), Ecell decreases, and vice-versa, connecting electrochemistry to chemical equilibrium.

The standard cell potential (E°cell) for a voltaic cell is calculated using E°cell = E°cathode − E°anode, where E° values come from standard reduction potential tables. A positive E°cell indicates a spontaneous reaction capable of producing electricity. Reduction occurs at the cathode (higher potential), and oxidation occurs at the anode (lower potential). Cell notation is written as: Anode|Anode...

Voltaic (or Galvanic) cells convert chemical energy into electrical energy using a spontaneous redox reaction. The reaction is split into two half-cells: the anode (where oxidation occurs) and the cathode (where reduction occurs). Electrons flow through an external wire from the anode to the cathode, creating current. A salt bridge connects the solutions, allowing ions to flow to maintain electric...

To balance redox reactions, they are split into oxidation and reduction half-reactions. The goal is to conserve both mass and charge. In acidic solutions, H2O balances oxygen, and H+ balances hydrogen. In basic solutions, the reaction is first balanced as if it were acidic, and then OH- ions are added to neutralize any H+. Finally, the half-reactions are multiplied so the electrons cancel out when...

Redox (Oxidation-Reduction) reactions involve the transfer of electrons. Oxidation is the loss of electrons (LEO), and Reduction is the gain of electrons (GER). These processes always occur simultaneously. Oxidation numbers are bookkeeping tools used to track this transfer. An increase in the oxidation number means oxidation occurred, while a decrease means reduction occurred. These reactions are...

Gibbs Free Energy (ΔG) predicts reaction spontaneity using the equation: ΔG = ΔH - TΔS. A negative ΔG means the reaction is spontaneous (happens on its own). This value combines enthalpy (ΔH), which is heat change, and entropy (ΔS), which is disorder. The reaction is spontaneous only at certain temperatures if ΔH and ΔS have the same sign.

This episode defines entropy (S) as a measure of the disorder or the number of ways energy and matter can be arranged in a system. Entropy naturally increases when a substance changes phase from solid to liquid to gas, as temperature increases, or when a reaction produces more gas molecules. The change in standard entropy is calculated by subtracting reactant entropies from product entropies, and...

This episode explains that not all salts are neutral; their pH depends on the origin of their ions. A salt is formed from an acid-base neutralization reaction. When dissolved, ions from weak acids or weak bases can undergo ion hydrolysis—reacting with water to form H3O+ (acidic) or OH- (basic) ions. The pH is predicted by its parent compounds: strong acid/strong base yields neutral; strong acid/we...

Indicators are weak acids or bases that change color based on the solution's pH. The color change happens because the indicator exists in an equilibrium between two forms, each having a different color. The goal is to choose an indicator whose transition range closely matches the equivalence point pH of the titration. For example, phenolphthalein is ideal for weak acid-strong base titrations (...

This episode introduces titration, a technique used to determine an unknown concentration (analyte) using a solution of known concentration (titrant). The focus is the strong acid–strong base titration, where reactants fully dissociate. The equivalence point is reached when moles of H+ equal moles of OH-, resulting in a neutral pH of 7.0. Beyond this point, the pH rises sharply. Calculations rely...

A buffer is a solution that resists changes in pH when small amounts of acid or base are added. It must contain a weak acid and its conjugate base (or a weak base and its conjugate acid). When acid (H+) is added, the conjugate base absorbs it; when base (OH-) is added, the weak acid neutralizes it. The pH of a buffer is calculated using the Henderson–Hasselbalch equation. Buffers, like the carboni...

Weak acids and bases partially dissociate in water, establishing equilibrium. Their strength is measured by the acid dissociation constant (Ka) and the base dissociation constant (Kb). A larger Ka or Kb indicates a stronger species. The constants are linked by the vital relationship: Ka x Kb = Kw, where Kw = 1.0 x 10-14 at 25°C. This relationship connects an acid's strength to the strength of...

The episode defines strong acids and strong bases as those that completely ionize (dissociate) in water, meaning 100% of the molecules break apart. This strength is independent of concentration. Memorizing the few common strong acids (like HCl and H2SO4) and strong bases (Group 1 and 2 hydroxides) is critical. Because they ionize fully, the concentration of the strong acid or base directly equals...

The autoionization of water, where H2O acts as both an acid and a base, is the focus of this episode. This process generates H3O+ and OH- ions. The equilibrium constant for this reaction is the Ion-Product Constant for Water, Kw, expressed as Kw = [H3O+][OH-]. At 25°C, the value of Kw is 1.0 x 10-14. This constant is essential for all aqueous solutions as it directly links the concentrations of th...

This episode discusses Conjugate Acid-Base Pairs as a necessary outcome of the Brønsted-Lowry definition. When an acid donates a proton (H+), it forms its conjugate base; when a base accepts a proton, it forms its conjugate acid. These pairs always differ by exactly one proton. Crucially, the strength of an acid is inversely related to the strength of its conjugate base. In any acid-base reaction,...

Acids and bases are fundamental chemical concepts defined by how they behave in solution. The Arrhenius definition states that acids produce H+ ions and bases produce OH- ions in water. A broader view is the Brønsted-Lowry definition, where an acid is a proton (H+) donor and a base is a proton acceptor. The most inclusive is the Lewis definition, identifying acids as electron-pair acceptors and ba...

This episode focuses on the Equilibrium Constant (K), which mathematically quantifies the position of a chemical equilibrium. K is defined by the expression: Products over Reactants, where the molar concentration of each substance, represented by brackets [ ], is raised to the power of its stoichiometric coefficient. A crucial rule is to exclude pure solids (s) and pure liquids (l) from the K expr...