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Questions and Answers
The energy of a system is the key determinant of equilibrium, structure and stability.
True
Ideal gases exhibit defined spatial relationships and significant chemical interactions between molecules.
False
Boyle's law describes the relationship between pressure and volume at constant temperature for an ideal gas.
True
Under all conditions, all gases behave ideally.
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Dynamic equilibria occur only in systems that have reached stability.
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The relationship between energy of a system and the equilibrium constant K is essential for understanding chemical processes.
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Complex pharmaceutical systems cannot be developed from theories based on simple systems such as ideal gases.
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Charles’ law examines the relationship between volume and temperature of a fixed amount of an ideal gas while keeping pressure constant.
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The change in enthalpy (ΔH) solely determines the direction of spontaneous change in a process.
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Entropy (S) is defined as the degree of order or organization in a system.
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Heat flows from a colder body to a hotter body during spontaneous processes.
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A process can occur spontaneously in the reverse direction without any intervention.
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As temperature decreases, the entropy of a single component increases.
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The internal energy of an isolated system can change over time.
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The work done on a system is considered positive when expanding the volume at constant pressure.
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The molecular mass of oxygen (O2) is 32 g mol−1.
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The formula for the First Law of Thermodynamics is ΔU = q + w.
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The pressure inside a cylinder will not leak unless the temperature exceeds 1.0 x 10^6 Pa.
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The mole fraction of oxygen (O2) in air is typically around 0.21.
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According to Boyle's Law, at constant temperature, the pressure is directly proportional to the volume.
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To convert temperature from Celsius to Kelvin, you add 273.15.
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In an ideal gas, energy due to interactions between molecules is significant.
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Avogadro’s Hypothesis states that samples of different gases at the same pressure, volume, and temperature contain the same number of molecules.
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The formula PV = nRT is not valid when calculating the amount of gas in a given volume.
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Charles' Law indicates that volume is proportional to temperature at constant pressure.
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Heat absorbed by a system is quantified by a positive value of q.
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The ideal gas law equation is expressed as PV = nRT.
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The mole fraction of a component in a mixture is defined as the number of moles of that component divided by the total number of moles in the mixture.
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The constant R in the ideal gas law equation varies with changes in temperature.
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Pressure and volume of an ideal gas are related by Avogadro’s Hypothesis.
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One mole of a pure substance contains approximately 6.022 x 10^23 entities.
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In a mixture of ideal gases, the total pressure is the sum of the partial pressures of each gas.
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For n moles of an ideal gas, the temperature must always be expressed in degrees Celsius for calculations.
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The value of ΔHf⁰ for fumaric acid is higher than that for maleic acid.
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Hess's Law states that ΔH for a process depends solely on the total enthalpy change of a system.
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The standard enthalpy of formation ΔHf° of Cl2 (g) is equal to zero.
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The reaction of glucose and oxygen includes forming glucose as a product.
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The calculated value of ΔHrxn for the reaction of C2H4 and Cl2 is −219.5 kJ mol−1.
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The value of ΔHf⁰ for CS2 (l) calculated using Hess's Law is 129.7 kJ mol−1.
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The ΔH for a reaction at constant pressure is generally represented as ΔHrxn.
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The enthalpy of formation for a compound is always a positive value.
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For the reaction of fumaric acid converting to maleic acid, ΔHrxn is calculated by taking the difference of their enthalpies of formation.
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At 305 K, the enthalpy change during glucose metabolism is negligible.
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Study Notes
Structure and Stability of Pharmaceutical Systems
- Equilibrium constants and dynamic equilibria are key elements of structure and stability.
- Pharmaceutical systems are complex, but simplified systems can be used to develop theories.
Energy and Equilibrium
- The energy of a system is the key determinant of equilibrium, structure, and stability.
- Ideal gases are the simplest systems to understand.
- Ideal gases consist of molecules moving randomly with no interactions between them.
Ideal Gases
- Some gases behave close to ideal under specific conditions.
- Boyle's law relates pressure to volume at constant temperature: P ∝ 1/V.
- Charles' law relates volume to temperature at constant pressure: V ∝ T.
- The ideal gas law combines Boyle's and Charles' law: PV = nRT, where R is the gas constant.
Mixtures of Ideal Gases
- The total pressure of a mixture of ideal gases is the sum of the partial pressures of each component.
- Mole fraction is used to determine the proportion of each component in the mixture.
The First Law of Thermodynamics
- Energy cannot be created or destroyed.
- Internal energy (U) is the total energy of a system.
- For ideal gases, internal energy is due to translational, rotational, and vibrational motion.
- The internal energy of an isolated system is constant.
Changes to the Internal Energy of a System
- Changes in internal energy (ΔU) can occur through heat transfer (q) and work (w).
- ΔU = q + w
Work and Pressure-Volume Changes
- Work done on a system is positive; work done by a system is negative.
- Work done by a system expanding at constant pressure is P * ΔV.
Hess's Law and Enthalpies of Reaction
- The enthalpy change of a reaction is independent of the path taken.
- Enthalpy changes for multi-step processes can be calculated by adding the changes for each step.
The Direction of Spontaneous Change
- The first law of thermodynamics states energy is conserved.
- Entropy is a measure of disorder or randomness.
- Changes in enthalpy (ΔH) and entropy (ΔS) determine the direction of change.
Spontaneous Processes
- Many processes occur spontaneously in one direction, like heat flowing from hot to cold.
- Entropy increases for spontaneous processes.
- Reverse processes require work or intervention.
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Description
Explore the fascinating concepts of structure, stability, and equilibrium in pharmaceutical systems. This quiz also covers ideal gas laws, including Boyle's and Charles' laws, to help you understand the behavior of gases in various conditions.
