Thermodynamics Quiz

The overall free energy of a real system is the sum of the contributions from each component, represented by their respective chemical potentials.

In ideal systems, free energy changes can be expressed simply as $ riangle G° = -RT ext{ln}K_{eq}$, while in real systems, it's framed as $ riangle G - riangle G° = RT ext{ln}K_{eq}$ indicating dependency on system conditions.

Activities account for the non-ideal behavior of components in real systems and should be used in equilibrium expressions over concentrations.

<p>In a system not at equilibrium, $ riangle G$ represents the change in free energy that results from the difference between the system's current state and the equilibrium state.</p> Signup and view all the answers

<p>The chemical potential of a component in a solution is defined as $ ext{μ}_i = ext{μ}_i° + RT ext{ln} a_i$, incorporating both standard chemical potential and the activity of the component.</p> Signup and view all the answers

<p>ΔH indicates the change in enthalpy, which helps assess whether a process is exothermic or endothermic, but it does not alone determine spontaneity.</p> Signup and view all the answers

<p>Entropy relates to the degree of disorder, with an increase in entropy (ΔS &gt; 0) often indicating a spontaneous process.</p> Signup and view all the answers

<p>A process with positive ΔH can be spontaneous if it has a sufficiently large positive ΔS resulting in a greater overall increase in the Gibbs free energy change.</p> Signup and view all the answers

<p>Heat naturally flows from hotter to colder bodies, signifying that this direction of heat transfer is spontaneous.</p> Signup and view all the answers

<p>Molecular mixing occurs spontaneously in one direction, from ordered (separated) to disordered (mixed) when the partition is removed.</p> Signup and view all the answers

<p>To predict the equilibrium position, both the change in enthalpy (ΔH) and the change in entropy (ΔS) must be considered.</p> Signup and view all the answers

<p>Yes, a process can occur in the reverse direction, but it would require external intervention to overcome the natural spontaneous tendency.</p> Signup and view all the answers

<p>Temperature plays a vital role since entropy decreases as temperature decreases, indicating lower disorder and less spontaneity.</p> Signup and view all the answers

<p>The phase with the lowest free energy G at temperature T is the most stable.</p> Signup and view all the answers

<p>Solids have large negative enthalpy and small entropy, making them the most stable phase at low temperatures.</p> Signup and view all the answers

<p>Gas phases have enthalpy close to 0 and large positive entropy, leading to higher stability at high temperatures.</p> Signup and view all the answers

<p>The Phase Rule (F = C - P + 2) indicates the number of degrees of freedom for changing temperature and pressure without altering phases.</p> Signup and view all the answers

<p>A phase diagram illustrates the conditions, specifically temperature and pressure, at which different phases coexist and change from one to another.</p> Signup and view all the answers

<p>Tvap is the temperature of vaporization, and Tfus is the temperature of fusion; these points indicate phase transitions for pure substances.</p> Signup and view all the answers

<p>A dosage formulation may contain multiple phases and components, complicating the equilibrium and stability of the formulation.</p> Signup and view all the answers

<p>Solids are typically the most stable state at low temperatures due to their large negative enthalpy and low entropy.</p> Signup and view all the answers

<p>Degrees of freedom (F) quantify how many independent changes can be made to phase conditions without changing the number of phases.</p> Signup and view all the answers

<p>Understanding phase equilibria is crucial for predicting stability and interactions in complex dosage forms that affect drug efficacy.</p> Signup and view all the answers

<p>It represents the relationship between the degrees of freedom (F), the number of components (C), and the number of phases (P) present in the system.</p> Signup and view all the answers

<p>The eutectic point is where solid and liquid phases coexist in equilibrium at a fixed temperature and composition.</p> Signup and view all the answers

<p>Composition refers to the percentage of each component (A and B) present in the mixture.</p> Signup and view all the answers

<p>The four regions indicate the states of the system: all liquid, all solid, two regions of solid suspended in liquid, and the eutectic point.</p> Signup and view all the answers

<p>It exhibits clear phase behavior and distinct regions that correspond to different states and compositions.</p> Signup and view all the answers

<p>As temperature decreases, the composition may approach the eutectic point where solid and liquid phases can coexist.</p> Signup and view all the answers

<p>One region contains solid A at a higher percentage of A, while the other region contains solid B at a higher percentage of B.</p> Signup and view all the answers

<p>Empirical measurement is necessary to identify the exact eutectic point since it varies based on the specific components involved.</p> Signup and view all the answers

<p>Phases refer to the distinct states of matter (solid, liquid) present in the system at specific compositions and temperatures.</p> Signup and view all the answers

<p>Temperature plays a critical role in determining which phases are stable and in what proportions they exist.</p> Signup and view all the answers

<p>A negative $ riangle G$ indicates that the process is spontaneous and will proceed in the preferred direction.</p> Signup and view all the answers

<p>The term $ riangle H$ represents the change in enthalpy of the system.</p> Signup and view all the answers

<p>A process reaches equilibrium when $ riangle G = 0$.</p> Signup and view all the answers

<p>A positive $ riangle S$ indicates increased disorder, largely due to the release of solvent molecules and ionic species.</p> Signup and view all the answers

<p>The process is considered to go to completion because it is highly favored thermodynamically with a significant negative $ riangle G$.</p> Signup and view all the answers

<p>The standard free energy change $ riangle G^ heta$ is the change in free energy under standard conditions, crucial for predicting reaction spontaneity.</p> Signup and view all the answers

<p>Using the equation, $ riangle S^ heta = rac{ riangle H - riangle G}{T} = rac{-20.1 - (-30.5)}{310} = 0.049 kJ K^{-1} mol^{-1}$.</p> Signup and view all the answers

<p>The temperature is calculated as $T &gt; rac{ riangle H}{ riangle S} = rac{250800}{752} ightarrow T &gt; 333.3$ K and hence above 60.3 °C.</p> Signup and view all the answers

<p>A high positive value of $ riangle H$ suggests the reaction is endothermic, requiring energy input to proceed.</p> Signup and view all the answers

<p>The relative contributions can be analyzed through $ riangle G$, where if the $ riangle H$ is small &amp; positive but $ riangle S$ is significantly positive, $ riangle G$ can still be negative, indicating spontaneity.</p> Signup and view all the answers

<p>The law of mass action states that the rate of a reaction is proportional to the product of the concentrations of the reactants, which allows for the determination of equilibrium concentrations in dynamic equilibrium.</p> Signup and view all the answers

<p>The equilibrium constant (Keq) quantifies the ratio of the concentrations of products to reactants at equilibrium, providing insight into the favorability of a reaction.</p> Signup and view all the answers

<p>Drug partitioning between aqueous and lipid phases influences the availability and absorption of the drug in biological systems, thereby affecting its therapeutic efficacy.</p> Signup and view all the answers

<p>Stoichiometries determine the coefficients used in the equilibrium constant equation, indicating the relative amounts of reactants and products involved in the chemical reaction.</p> Signup and view all the answers

<p>When a chemical system reaches dynamic equilibrium, the concentrations of reactants and products remain constant, although individual reactions continue to occur in both directions.</p> Signup and view all the answers

<p>Dynamic equilibrium can be illustrated by reversible reactions, where the rates of the forward and reverse reactions become equal, leading to stable concentrations of all species involved.</p> Signup and view all the answers

<p>Temperature can shift the equilibrium position of a reaction, favoring either the reactants or products depending on whether the reaction is exothermic or endothermic.</p> Signup and view all the answers

<p>In equilibrium reactions, 'concentration' refers to the amount of a substance present per unit volume, which affects the reaction rates and equilibrium constant.</p> Signup and view all the answers

<p>Chemical potential reflects the change in free energy with respect to the number of moles of a component, thus allowing for the total free energy of a real system to be expressed as the sum of the chemical potentials of each component multiplied by their respective mole fractions.</p> Signup and view all the answers

<p>Using activities provides a more accurate representation of the effective concentration of a species in a solution, accounting for interactions between molecules, leading to better predictions of equilibrium behavior in real systems.</p> Signup and view all the answers

<p>Temperature and pressure directly influence the chemical potential by affecting kinetic energy and molecular interactions, which alter how components behave and interact with one another within the system.</p> Signup and view all the answers

<p>At equilibrium, the change in free energy $ riangle G$ is zero, indicating that the forward and reverse reactions occur at the same rate, and the system is in a state of dynamic balance.</p> Signup and view all the answers

<p>The equation signifies that the total free energy of a system is the sum of the contributions from each component, each represented by their chemical potential weighted by the number of moles, reflecting the system's composition.</p> Signup and view all the answers

<p>A positive change in entropy (ΔS) indicates an increase in disorder, which favors spontaneity in a process.</p> Signup and view all the answers

<p>Enthalpy change (ΔH) helps predict whether a reaction releases or absorbs heat, impacting its spontaneity.</p> Signup and view all the answers

<p>If the enthalpic contribution (ΔH) is sufficiently large and negative, it can drive the process despite a decrease in entropy.</p> Signup and view all the answers

<p>The first law of thermodynamics states that energy is conserved, indicating that the energy balance must be maintained during spontaneous changes.</p> Signup and view all the answers

<p>As temperature decreases, the entropy of a system typically decreases, indicating a reduction in disorder.</p> Signup and view all the answers

<p>Gases spontaneously mix due to an increase in entropy, reflecting the natural tendency toward disorder in thermodynamic systems.</p> Signup and view all the answers

<p>Interventions can drive non-spontaneous processes to occur, often requiring an external energy input to overcome entropic barriers.</p> Signup and view all the answers

<p>Entropy is classified as a state function because its value depends only on the current state of the system, not on the path taken to reach that state.</p> Signup and view all the answers

<p>Heat spontaneously flows from a hotter body to a colder body due to the tendency to reach thermal equilibrium, reflecting an increase in overall entropy.</p> Signup and view all the answers

<p>Assessing the direction of spontaneous change helps determine how and when a system will reach equilibrium by balancing enthalpy and entropy influences.</p> Signup and view all the answers

<p>A and B become fully miscible, forming a single liquid phase.</p> Signup and view all the answers

<p>The presence of stronger A-A and B-B interactions than A-B interactions.</p> Signup and view all the answers

<p>Below the lower critical temperature, A and B are less miscible, leading to phase separation.</p> Signup and view all the answers

<p>It illustrates the phase behavior of three components at constant temperature and pressure.</p> Signup and view all the answers

<p>They indicate compositions consisting of only two components from the three present.</p> Signup and view all the answers

<p>The interaction between triethylamine and water is a known example.</p> Signup and view all the answers

<p>Surfactants reduce the interfacial tension between the liquid phases.</p> Signup and view all the answers

<p>Point O represents a specific ratio among the three components, dictating the phase behavior.</p> Signup and view all the answers

<p>They visually represent the conditions under which different phases coexist.</p> Signup and view all the answers

<p>As temperature increases, the miscibility of the two liquids improves until they become fully mixed.</p> Signup and view all the answers

<p>Large drops in entropy at phase transitions indicate a transition from a less ordered to a more ordered phase, reflecting a significant change in the system's organization.</p> Signup and view all the answers

<p>Within the same phase, decreasing temperature generally leads to a decrease in entropy as the system becomes more ordered.</p> Signup and view all the answers

<p>The 3rd Law of Thermodynamics states that at 0 K, the entropy ($S$) of a perfect crystal is equal to 0 J mol−1 K−1.</p> Signup and view all the answers

<p>Heat is expressed as $q = T \times S$, indicating that heat transfer is directly proportional to both the temperature and the change in entropy.</p> Signup and view all the answers

<p>Reversible processes can be reversed without changes in the system or surroundings, while irreversible processes cannot return to their original state once changed.</p> Signup and view all the answers

<p>Understanding $\Delta S$ is crucial because a positive change in entropy often indicates that a process can occur spontaneously by increasing disorder in the universe.</p> Signup and view all the answers

<p>The intensity factor represents the driving force (e.g., force or temperature) while the capacity factor represents the extent of that force (e.g., distance or entropy).</p> Signup and view all the answers

<p>Dynamic equilibrium implies that, despite ongoing processes, the system remains in a consistent state at equilibrium, with no net change in its properties.</p> Signup and view all the answers

<p>A system at absolute zero would imply that molecular motion ceases completely, leading to maximum order and minimal entropy.</p> Signup and view all the answers

<p>An irreversible process signifies that energy transformations result in a net increase in entropy, leading the system away from its original state.</p> Signup and view all the answers