Free Energy of Dissolution - AP Chemistry
Card 1 of 30
Which quantity becomes zero at the dissolution equilibrium point?
Which quantity becomes zero at the dissolution equilibrium point?
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$\triangle G$. Free energy equals zero when forward and reverse rates are equal.
$\triangle G$. Free energy equals zero when forward and reverse rates are equal.
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Identify the factor that primarily affects $\triangle S$ in dissolution.
Identify the factor that primarily affects $\triangle S$ in dissolution.
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Molecular disorder. Dissolution typically increases randomness as molecules spread out.
Molecular disorder. Dissolution typically increases randomness as molecules spread out.
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Determine the spontaneity: $\triangle H = 5 \text{ kJ/mol}$, $T = 298 \text{ K}$, $\triangle S = 30 \text{ J/mol·K}$.
Determine the spontaneity: $\triangle H = 5 \text{ kJ/mol}$, $T = 298 \text{ K}$, $\triangle S = 30 \text{ J/mol·K}$.
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Spontaneous. $\triangle G = 5000 - 298(30) = 5000 - 8940 = -3940$ J/mol, so spontaneous.
Spontaneous. $\triangle G = 5000 - 298(30) = 5000 - 8940 = -3940$ J/mol, so spontaneous.
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What does a positive $\triangle S$ indicate about entropy in dissolution?
What does a positive $\triangle S$ indicate about entropy in dissolution?
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Entropy increases. Positive $\triangle S$ means the system becomes more disordered.
Entropy increases. Positive $\triangle S$ means the system becomes more disordered.
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Determine the spontaneity: $\triangle H = 5 \text{ kJ/mol}$, $T = 298 \text{ K}$, $\triangle S = 30 \text{ J/mol·K}$.
Determine the spontaneity: $\triangle H = 5 \text{ kJ/mol}$, $T = 298 \text{ K}$, $\triangle S = 30 \text{ J/mol·K}$.
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Spontaneous. $\triangle G = 5000 - 298(30) = 5000 - 8940 = -3940$ J/mol, so spontaneous.
Spontaneous. $\triangle G = 5000 - 298(30) = 5000 - 8940 = -3940$ J/mol, so spontaneous.
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State the effect on $\triangle G$ if both $\triangle H$ and $\triangle S$ are positive.
State the effect on $\triangle G$ if both $\triangle H$ and $\triangle S$ are positive.
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Depends on $T$. Sign depends on whether $T\triangle S$ is greater or less than $\triangle H$.
Depends on $T$. Sign depends on whether $T\triangle S$ is greater or less than $\triangle H$.
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Calculate $\triangle H$ given $\triangle G = -3 \text{ kJ/mol}$, $T = 310 \text{ K}$, $\triangle S = 80 \text{ J/mol·K}$.
Calculate $\triangle H$ given $\triangle G = -3 \text{ kJ/mol}$, $T = 310 \text{ K}$, $\triangle S = 80 \text{ J/mol·K}$.
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$\triangle H = 21.8 \text{ kJ/mol}$. $\triangle H = \triangle G + T\triangle S = -3000 + 310(80) = 21800$ J/mol.
$\triangle H = 21.8 \text{ kJ/mol}$. $\triangle H = \triangle G + T\triangle S = -3000 + 310(80) = 21800$ J/mol.
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Identify the type of dissolution with $\triangle S > 0$ and $\triangle H < 0$.
Identify the type of dissolution with $\triangle S > 0$ and $\triangle H < 0$.
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Spontaneous dissolution. Both favorable enthalpy and entropy make $\triangle G$ negative at all temperatures.
Spontaneous dissolution. Both favorable enthalpy and entropy make $\triangle G$ negative at all temperatures.
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State the condition for a dissolution to be spontaneous at all temperatures.
State the condition for a dissolution to be spontaneous at all temperatures.
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$\triangle H < 0$, $\triangle S > 0$. Exothermic enthalpy and positive entropy ensure spontaneity.
$\triangle H < 0$, $\triangle S > 0$. Exothermic enthalpy and positive entropy ensure spontaneity.
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What is indicated by a positive $\triangle G$ in dissolution?
What is indicated by a positive $\triangle G$ in dissolution?
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Non-spontaneous process. Positive free energy means the process is thermodynamically unfavorable.
Non-spontaneous process. Positive free energy means the process is thermodynamically unfavorable.
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What determines the spontaneity of a dissolution process?
What determines the spontaneity of a dissolution process?
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Sign of $\triangle G$. Negative $\triangle G$ means spontaneous, positive means non-spontaneous.
Sign of $\triangle G$. Negative $\triangle G$ means spontaneous, positive means non-spontaneous.
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How does the dissolution of a gas in a liquid typically affect $\Delta S$?
How does the dissolution of a gas in a liquid typically affect $\Delta S$?
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$\Delta S$ decreases. Gas molecules become more ordered when dissolved in liquid.
$\Delta S$ decreases. Gas molecules become more ordered when dissolved in liquid.
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What is the relationship between $\triangle H$ and $\triangle S$ in spontaneous dissolution?
What is the relationship between $\triangle H$ and $\triangle S$ in spontaneous dissolution?
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$\triangle H < T\triangle S$. For spontaneity, the entropy term must overcome unfavorable enthalpy.
$\triangle H < T\triangle S$. For spontaneity, the entropy term must overcome unfavorable enthalpy.
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Calculate $\triangle G$ given $\triangle H = 10 \text{ kJ/mol}$, $T = 298 \text{ K}$, $\triangle S = 50 \text{ J/mol·K}$.
Calculate $\triangle G$ given $\triangle H = 10 \text{ kJ/mol}$, $T = 298 \text{ K}$, $\triangle S = 50 \text{ J/mol·K}$.
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$\triangle G = -4.9 \text{ kJ/mol}$. $\triangle G = 10000 - 298(50) = 10000 - 14900 = -4900$ J/mol.
$\triangle G = -4.9 \text{ kJ/mol}$. $\triangle G = 10000 - 298(50) = 10000 - 14900 = -4900$ J/mol.
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What is the sign of $\triangle G$ when dissolution is at equilibrium?
What is the sign of $\triangle G$ when dissolution is at equilibrium?
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$\triangle G = 0$. Zero free energy indicates the system has reached equilibrium.
$\triangle G = 0$. Zero free energy indicates the system has reached equilibrium.
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Which factor affects the sign of $\triangle G$ at constant pressure and temperature?
Which factor affects the sign of $\triangle G$ at constant pressure and temperature?
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Enthalpy and entropy. Both enthalpy and entropy contributions determine free energy sign.
Enthalpy and entropy. Both enthalpy and entropy contributions determine free energy sign.
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Calculate $\triangle G$ with $\triangle H = 20 \text{ kJ/mol}$, $T = 350 \text{ K}$, $\triangle S = 70 \text{ J/mol·K}$.
Calculate $\triangle G$ with $\triangle H = 20 \text{ kJ/mol}$, $T = 350 \text{ K}$, $\triangle S = 70 \text{ J/mol·K}$.
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$\triangle G = -4.5 \text{ kJ/mol}$. $\triangle G = 20000 - 350(70) = 20000 - 24500 = -4500$ J/mol.
$\triangle G = -4.5 \text{ kJ/mol}$. $\triangle G = 20000 - 350(70) = 20000 - 24500 = -4500$ J/mol.
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What effect does increased pressure have on gas solubility in liquids?
What effect does increased pressure have on gas solubility in liquids?
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Increases solubility. Henry's law: gas solubility is directly proportional to pressure.
Increases solubility. Henry's law: gas solubility is directly proportional to pressure.
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What does a positive $\triangle S$ indicate about entropy in dissolution?
What does a positive $\triangle S$ indicate about entropy in dissolution?
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Entropy increases. Positive $\triangle S$ means the system becomes more disordered.
Entropy increases. Positive $\triangle S$ means the system becomes more disordered.
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Determine the spontaneity: $\Delta H = 5 \text{ kJ/mol}$, $T = 298 \text{ K}$, $\Delta S = 30 \text{ J/mol·K}$.
Determine the spontaneity: $\Delta H = 5 \text{ kJ/mol}$, $T = 298 \text{ K}$, $\Delta S = 30 \text{ J/mol·K}$.
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Spontaneous. $\Delta G = 5000 - 298(30) = 5000 - 8940 = -3940$ J/mol, so spontaneous.
Spontaneous. $\Delta G = 5000 - 298(30) = 5000 - 8940 = -3940$ J/mol, so spontaneous.
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Which parameter is zero for a process at equilibrium?
Which parameter is zero for a process at equilibrium?
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$\triangle G$. At equilibrium, the free energy change equals zero.
$\triangle G$. At equilibrium, the free energy change equals zero.
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Calculate the enthalpy change: $\Delta G = -5 \text{ kJ/mol}$, $T = 298 \text{ K}$, $\Delta S = 20 \text{ J/mol·K}$.
Calculate the enthalpy change: $\Delta G = -5 \text{ kJ/mol}$, $T = 298 \text{ K}$, $\Delta S = 20 \text{ J/mol·K}$.
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$\Delta H = 1.96 \text{ kJ/mol}$. $\Delta H = \Delta G + T \Delta S = -5000 + 298(20) = 1960$ J/mol.
$\Delta H = 1.96 \text{ kJ/mol}$. $\Delta H = \Delta G + T \Delta S = -5000 + 298(20) = 1960$ J/mol.
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Identify the factor that primarily affects $\triangle S$ in dissolution.
Identify the factor that primarily affects $\triangle S$ in dissolution.
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Molecular disorder. Dissolution typically increases randomness as molecules spread out.
Molecular disorder. Dissolution typically increases randomness as molecules spread out.
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State the sign of $\triangle G$ for a spontaneous dissolution.
State the sign of $\triangle G$ for a spontaneous dissolution.
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$\triangle G < 0$. Negative free energy indicates a thermodynamically favorable process.
$\triangle G < 0$. Negative free energy indicates a thermodynamically favorable process.
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What is the formula for Gibbs free energy change?
What is the formula for Gibbs free energy change?
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$\triangle G = \triangle H - T\triangle S$. Fundamental thermodynamic equation relating free energy to enthalpy and entropy.
$\triangle G = \triangle H - T\triangle S$. Fundamental thermodynamic equation relating free energy to enthalpy and entropy.
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What is the sign of $\triangle G$ when $\triangle H < 0$ and $\triangle S > 0$?
What is the sign of $\triangle G$ when $\triangle H < 0$ and $\triangle S > 0$?
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$\triangle G < 0$. Both terms favor spontaneity, making $\triangle G$ always negative.
$\triangle G < 0$. Both terms favor spontaneity, making $\triangle G$ always negative.
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Calculate $\triangle G$ when $\triangle H = 15 \text{ kJ/mol}$, $T = 300 \text{ K}$, $\triangle S = 60 \text{ J/mol·K}$.
Calculate $\triangle G$ when $\triangle H = 15 \text{ kJ/mol}$, $T = 300 \text{ K}$, $\triangle S = 60 \text{ J/mol·K}$.
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$\triangle G = -3 \text{ kJ/mol}$. $\triangle G = 15000 - 300(60) = 15000 - 18000 = -3000$ J/mol.
$\triangle G = -3 \text{ kJ/mol}$. $\triangle G = 15000 - 300(60) = 15000 - 18000 = -3000$ J/mol.
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What is the significance of $\triangle G = 0$ in dissolution?
What is the significance of $\triangle G = 0$ in dissolution?
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Equilibrium state. Zero free energy indicates the system is at thermodynamic equilibrium.
Equilibrium state. Zero free energy indicates the system is at thermodynamic equilibrium.
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What does a negative $\triangle S$ for dissolution indicate?
What does a negative $\triangle S$ for dissolution indicate?
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Entropy decreases. Negative entropy change indicates decreased molecular disorder.
Entropy decreases. Negative entropy change indicates decreased molecular disorder.
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What is the unit of Gibbs free energy change?
What is the unit of Gibbs free energy change?
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Joules (J) or kilojoules (kJ). Energy units for thermodynamic quantities in the SI system.
Joules (J) or kilojoules (kJ). Energy units for thermodynamic quantities in the SI system.
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