Thermochemistry of Gases

The work done is equal to the pressure multiplied by the change in volume, expressed as $w = -P\Delta V$.

Enthalpy (H) is defined as $H = U + PV$ and signifies the heat content of a system at constant pressure, important for analyzing heat transfers during chemical processes.

At constant volume, $\Delta U = q_v$, indicating that the change in internal energy equals the heat transferred since there is no work done ($\Delta V = 0$).

<p>Intensive properties are independent of system size, such as pressure (P); extensive properties depend on system size, such as internal energy (U).</p> Signup and view all the answers

<p>An endothermic process has a positive enthalpy change ($\Delta H &gt; 0$), indicating heat absorption; an exothermic process has a negative enthalpy change ($\Delta H &lt; 0$), indicating heat release.</p> Signup and view all the answers

<p>$\Delta H = \Delta U + P\Delta V$, showing that enthalpy change accounts for internal energy change and the work associated with volume change.</p> Signup and view all the answers

<p>State functions, like $\Delta U$ and $\Delta H$, depend only on the current state of the system and not on the path taken to reach that state.</p> Signup and view all the answers

<p>The enthalpy of formation is defined as the heat absorbed when one mole of a compound is formed from its elements in their most stable forms, typically measured at 25 °C and 1 atmosphere pressure.</p> Signup and view all the answers

<p>1.0 x 10^6 Pa</p> Signup and view all the answers

<p>The heat gained by the melting ice equals the heat lost by the surrounding water, resulting in no overall change in the entropy of the universe.</p> Signup and view all the answers

<p>32 g mol−1</p> Signup and view all the answers

<p>First Law of Thermodynamics</p> Signup and view all the answers

<p>The change in entropy is 22.0 J mol−1 K−1.</p> Signup and view all the answers

<p>Change in internal energy of a system.</p> Signup and view all the answers

<p>The entropy of the cold object increases while the entropy of the hot object decreases, leading to an overall increase in the entropy of the universe.</p> Signup and view all the answers

<p>In reversible processes, the entropy change is calculated as ∆S = q_rev / T, whereas in irreversible processes, the entropy change is greater than this value (∆S &gt; q_irr / T).</p> Signup and view all the answers

<p>It is quantified by the value of w.</p> Signup and view all the answers

<p>The second law implies that the entropy of the universe always increases in spontaneous processes.</p> Signup and view all the answers

<p>ΔU = q + w</p> Signup and view all the answers

<p>It corresponds to expansion, leading to energy transfer from the gas.</p> Signup and view all the answers

<p>Through heat transfer or work done.</p> Signup and view all the answers

<p>It is quantified by the value of q.</p> Signup and view all the answers

<p>No changes to phases or components occur.</p> Signup and view all the answers

<p>The energy of a system influences the equilibrium constant K by determining the position of equilibrium; higher energy states correspond to changes in K.</p> Signup and view all the answers

<p>Ideal gases are characterized by random molecular movement, no intermolecular interactions, and negligible molecular volume.</p> Signup and view all the answers

<p>In pharmaceutical applications, a system at equilibrium signifies stability, while a system not at equilibrium indicates a tendency for change, affecting drug behavior.</p> Signup and view all the answers

<p>Dynamic equilibrium illustrates how pharmaceutical systems continuously adjust to maintain stability despite ongoing processes.</p> Signup and view all the answers

<p>Studies on ideal gases lay the foundational principles of thermodynamics, which can be adapted to understand interactions in complex pharmaceutical systems.</p> Signup and view all the answers

<p>Boyle's Law states that at constant temperature, the pressure of a gas is inversely proportional to its volume, highlighting the relationship between P and V in ideal gases.</p> Signup and view all the answers

<p>A pharmaceutical system not at equilibrium may experience degradation or altered efficacy, affecting therapeutic outcomes and patient safety.</p> Signup and view all the answers

<p>Observing gas behavior under changing P, V, and T informs drug formulation by revealing how environmental factors influence drug stability and delivery.</p> Signup and view all the answers

<p>The key assumptions are that the gas molecules do not interact chemically and occupy no physical space, which simplifies calculations and predictions.</p> Signup and view all the answers

<p>Starting from simple systems allows for easier understanding and application of fundamental principles before tackling the complexities of pharmaceutical systems.</p> Signup and view all the answers

<p>Spontaneous processes are associated with an increase in entropy, indicating a move towards greater disorder.</p> Signup and view all the answers

<p>The first law of thermodynamics accounts for energy conservation, but does not provide information about the direction of spontaneous change.</p> Signup and view all the answers

<p>This signifies that the formation of glucose from its elements releases energy, making the process exothermic.</p> Signup and view all the answers

<p>Heat flows from hot to cold due to the second law of thermodynamics, which states that entropy of an isolated system tends to increase.</p> Signup and view all the answers

<p>The change in entropy (ΔS) is crucial because a positive ΔS indicates that the process is likely to be spontaneous.</p> Signup and view all the answers

<p>Entropy decreases as temperature decreases, showing that lower temperatures correspond with greater order in a system.</p> Signup and view all the answers

<p>This demonstrates a spontaneous process where the increase in entropy occurs as the gas molecules move towards a state of greater disorder.</p> Signup and view all the answers

<p>While reverse processes can occur, they typically require energy input or specific conditions to overcome the natural tendency towards spontaneity.</p> Signup and view all the answers

<p>Both ΔH and ΔS are essential to understanding equilibrium, as they together determine whether a process will favor products or reactants at equilibrium.</p> Signup and view all the answers

<p>This implies that O2 is considered a reference state and its formation does not require or release energy, making it a stable elemental form.</p> Signup and view all the answers