Introduction to Enthalpy of Reaction - AP Chemistry
Card 1 of 30
State the formula for change in enthalpy ($\Delta H$).
State the formula for change in enthalpy ($\Delta H$).
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$\Delta H = H_{products} - H_{reactants}$. Difference between final and initial enthalpy states.
$\Delta H = H_{products} - H_{reactants}$. Difference between final and initial enthalpy states.
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Which principle states that the total energy of an isolated system remains constant?
Which principle states that the total energy of an isolated system remains constant?
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The First Law of Thermodynamics. Conservation of energy in closed systems.
The First Law of Thermodynamics. Conservation of energy in closed systems.
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Calculate the $\Delta H$ for the decomposition of $2$ moles of $H_2O_2$ given $\Delta H = -196$ kJ/mol.
Calculate the $\Delta H$ for the decomposition of $2$ moles of $H_2O_2$ given $\Delta H = -196$ kJ/mol.
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$\Delta H = -392$ kJ. Multiply per-mole enthalpy by number of moles reacting.
$\Delta H = -392$ kJ. Multiply per-mole enthalpy by number of moles reacting.
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What is the enthalpy change ($\Delta H$) when one mole of water vapor condenses?
What is the enthalpy change ($\Delta H$) when one mole of water vapor condenses?
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$\Delta H = -40.7$ kJ/mol. Reverse of vaporization with opposite sign.
$\Delta H = -40.7$ kJ/mol. Reverse of vaporization with opposite sign.
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What does a positive $\Delta H$ indicate about a reaction?
What does a positive $\Delta H$ indicate about a reaction?
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A positive $\Delta H$ indicates an endothermic reaction. Heat is absorbed from the surroundings during the reaction.
A positive $\Delta H$ indicates an endothermic reaction. Heat is absorbed from the surroundings during the reaction.
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What is the enthalpy of vaporization?
What is the enthalpy of vaporization?
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It is the enthalpy change when one mole of liquid turns into gas. Evaporation process requiring energy input for phase change.
It is the enthalpy change when one mole of liquid turns into gas. Evaporation process requiring energy input for phase change.
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State the enthalpy change for the formation of one mole of carbon dioxide from carbon and oxygen.
State the enthalpy change for the formation of one mole of carbon dioxide from carbon and oxygen.
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$\Delta H_f^\circ = -393.5$ kJ/mol. Standard formation enthalpy for carbon dioxide from elements.
$\Delta H_f^\circ = -393.5$ kJ/mol. Standard formation enthalpy for carbon dioxide from elements.
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Find the enthalpy change for the reaction given $H_{products} = 100$ kJ and $H_{reactants} = 150$ kJ.
Find the enthalpy change for the reaction given $H_{products} = 100$ kJ and $H_{reactants} = 150$ kJ.
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$\Delta H = -50$ kJ. Using $\Delta H = H_{products} - H_{reactants} = 100 - 150$.
$\Delta H = -50$ kJ. Using $\Delta H = H_{products} - H_{reactants} = 100 - 150$.
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What does the symbol $\Delta H_{rxn}$ represent?
What does the symbol $\Delta H_{rxn}$ represent?
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It represents the enthalpy change for a chemical reaction. Standard notation for reaction enthalpy under specified conditions.
It represents the enthalpy change for a chemical reaction. Standard notation for reaction enthalpy under specified conditions.
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What is the relationship between $\Delta H$ and $q$ at constant pressure?
What is the relationship between $\Delta H$ and $q$ at constant pressure?
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$\Delta H = q$ at constant pressure. Direct equivalence when pressure remains constant throughout.
$\Delta H = q$ at constant pressure. Direct equivalence when pressure remains constant throughout.
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Calculate the enthalpy change for a reaction if $q = 250$ J and $n = 0.5$ mol.
Calculate the enthalpy change for a reaction if $q = 250$ J and $n = 0.5$ mol.
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$\Delta H = 500$ J/mol. Using $\Delta H = \frac{q}{n} = \frac{250}{0.5}$.
$\Delta H = 500$ J/mol. Using $\Delta H = \frac{q}{n} = \frac{250}{0.5}$.
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What is meant by 'enthalpy of combustion'?
What is meant by 'enthalpy of combustion'?
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It is the enthalpy change when one mole of a substance burns completely in oxygen. Complete oxidation reaction with oxygen as the oxidizing agent.
It is the enthalpy change when one mole of a substance burns completely in oxygen. Complete oxidation reaction with oxygen as the oxidizing agent.
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Identify the enthalpy change for the evaporation of water.
Identify the enthalpy change for the evaporation of water.
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$\Delta H_{vap} = 40.7$ kJ/mol. Energy required for liquid-to-gas phase transition.
$\Delta H_{vap} = 40.7$ kJ/mol. Energy required for liquid-to-gas phase transition.
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Define the term 'standard state' in the context of enthalpy.
Define the term 'standard state' in the context of enthalpy.
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It is the physical state of a substance at 1 atm and 25°C. Reference conditions for comparing thermodynamic properties.
It is the physical state of a substance at 1 atm and 25°C. Reference conditions for comparing thermodynamic properties.
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What is the enthalpy of fusion?
What is the enthalpy of fusion?
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It is the enthalpy change when one mole of solid turns into liquid. Melting process requiring energy input for phase change.
It is the enthalpy change when one mole of solid turns into liquid. Melting process requiring energy input for phase change.
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Which type of reaction absorbs heat from the surroundings?
Which type of reaction absorbs heat from the surroundings?
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Endothermic reactions absorb heat. Positive $\Delta H$ indicates heat absorption from surroundings.
Endothermic reactions absorb heat. Positive $\Delta H$ indicates heat absorption from surroundings.
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What is the enthalpy of neutralization?
What is the enthalpy of neutralization?
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It is the enthalpy change when an acid and a base react to form water. Acid-base reaction forming water as the primary product.
It is the enthalpy change when an acid and a base react to form water. Acid-base reaction forming water as the primary product.
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What is the definition of enthalpy (H)?
What is the definition of enthalpy (H)?
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Enthalpy (H) is the heat content of a system at constant pressure. Represents total internal energy plus pressure-volume work.
Enthalpy (H) is the heat content of a system at constant pressure. Represents total internal energy plus pressure-volume work.
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Identify the components in the enthalpy change equation $\Delta H = q_p$.
Identify the components in the enthalpy change equation $\Delta H = q_p$.
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$q_p$ represents the heat absorbed or released at constant pressure. Heat transfer equals enthalpy change at constant pressure.
$q_p$ represents the heat absorbed or released at constant pressure. Heat transfer equals enthalpy change at constant pressure.
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Calculate the $\Delta H$ for a reaction using Hess's Law given multiple reactions.
Calculate the $\Delta H$ for a reaction using Hess's Law given multiple reactions.
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Add individual $\Delta H$ values to find total $\Delta H$. Sum intermediate steps to find overall enthalpy change.
Add individual $\Delta H$ values to find total $\Delta H$. Sum intermediate steps to find overall enthalpy change.
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Calculate $\Delta H$ using calorimetry data for a reaction.
Calculate $\Delta H$ using calorimetry data for a reaction.
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Use $q = mc\Delta T$ and $\Delta H = \frac{q}{n}$, where $n$ is moles. Combine heat capacity data with molar quantities.
Use $q = mc\Delta T$ and $\Delta H = \frac{q}{n}$, where $n$ is moles. Combine heat capacity data with molar quantities.
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What is the significance of a large negative $\Delta H$ value?
What is the significance of a large negative $\Delta H$ value?
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It indicates a strongly exothermic reaction. Large energy release indicates highly favorable reaction.
It indicates a strongly exothermic reaction. Large energy release indicates highly favorable reaction.
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What does a negative $\Delta H$ signify about a reaction?
What does a negative $\Delta H$ signify about a reaction?
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A negative $\Delta H$ indicates an exothermic reaction. Heat is released to the surroundings during the reaction.
A negative $\Delta H$ indicates an exothermic reaction. Heat is released to the surroundings during the reaction.
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What is the enthalpy change for the conversion of diamond to graphite?
What is the enthalpy change for the conversion of diamond to graphite?
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$\Delta H = -1.9$ kJ/mol. Slightly exothermic carbon allotrope transformation.
$\Delta H = -1.9$ kJ/mol. Slightly exothermic carbon allotrope transformation.
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What is the significance of enthalpy in chemical reactions?
What is the significance of enthalpy in chemical reactions?
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Enthalpy helps predict the heat exchange and spontaneity of reactions. Determines energy requirements and reaction feasibility.
Enthalpy helps predict the heat exchange and spontaneity of reactions. Determines energy requirements and reaction feasibility.
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What is the enthalpy change when 1 mol of water forms from hydrogen and oxygen?
What is the enthalpy change when 1 mol of water forms from hydrogen and oxygen?
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$\Delta H_f^\circ = -285.8$ kJ/mol. Standard formation enthalpy for liquid water from elements.
$\Delta H_f^\circ = -285.8$ kJ/mol. Standard formation enthalpy for liquid water from elements.
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What is the enthalpy change when one mole of ice melts to water at 0°C?
What is the enthalpy change when one mole of ice melts to water at 0°C?
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$\Delta H_{fus} = 6.01$ kJ/mol. Energy required for solid-to-liquid phase transition.
$\Delta H_{fus} = 6.01$ kJ/mol. Energy required for solid-to-liquid phase transition.
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Identify the enthalpy change for the evaporation of water.
Identify the enthalpy change for the evaporation of water.
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$\Delta H_{vap} = 40.7$ kJ/mol. Energy required for liquid-to-gas phase transition.
$\Delta H_{vap} = 40.7$ kJ/mol. Energy required for liquid-to-gas phase transition.
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What is the enthalpy change for the conversion of diamond to graphite?
What is the enthalpy change for the conversion of diamond to graphite?
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$\Delta H = -1.9$ kJ/mol. Slightly exothermic carbon allotrope transformation.
$\Delta H = -1.9$ kJ/mol. Slightly exothermic carbon allotrope transformation.
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Calculate the enthalpy change for a reaction if $q = 250$ J and $n = 0.5$ mol.
Calculate the enthalpy change for a reaction if $q = 250$ J and $n = 0.5$ mol.
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$\Delta H = 500$ J/mol. Using $\Delta H = \frac{q}{n} = \frac{250}{0.5}$.
$\Delta H = 500$ J/mol. Using $\Delta H = \frac{q}{n} = \frac{250}{0.5}$.
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