Thermochemistry Flashcards
What is thermochemistry?
Thermochemistry is the study of the heat energy associated with chemical reactions and changes of state.
What is an exothermic reaction?
An exothermic reaction is a chemical reaction where enrgy is transferred to the surroundings in the form of heat.
What is an endothermic reaction?
An endothermic reaction is a chemical reaction where energy is taken in from its surrounding in the form og heat.
What are some examples of exothermic reactions?
-Bond making
-Oxidation of fuels(Combustion)
-Respiration
What are some examples of endothermic reactions?
-Bond breaking
-Thermal Decomposition
Fill in the blank: The change in enthalpy (ΔH) for an exothermic reaction is _____.
negative
Fill in the blank: The change in enthalpy (ΔH) for an endothermic reaction is _____.
positive
What is the standard enthalpy change of formation?
The change in enthalpy when one mole of a compound is formed from its elements in their standard states under standard conditions.
What is the standard enthalpy change of combustion?
The change in enthalpy when one mole of a substance is completely combusted in oxygen under standard conditions.
What is the enthalpy change of reaction?
The change in enthalpy of any reaction at any number of moles of reactants involves.
What is the formula for calculating heat energy (q)?
q = mcΔT
In the formula q = mcΔT, what does ‘m’ represent?
mass of the substance
In the formula q = mcΔT, what does ‘c’ represent?
specific heat capacity of the substance
In the formula q = mcΔT, what does ‘ΔT’ represent?
change in temperature
What is Hess’s Law?
The total enthalpy change of a reaction is independent of the route taken from the reactants to the products.
What does the term ‘enthalpy’ refer to?
Enthalpy is a measure of the total energy of a thermodynamic system.
What does the term ‘bond enthalpy’ refer to?
The amount of energy needed to break a covalent bond during a chemical reaction.
What does the term ‘average bond enthalpy’ refer to?
The average balue of the enthalpy required to break a given type of covalent bond in a molecule in the gaseous state.
Fill in the blank: A calorimeter is used to measure the ____ of a chemical reaction.
heat change
What is the difference between specific heat capacity and molar heat capacity?
Specific heat capacity is the heat required to raise the temperature of one gram of a substance by one degree Celsius, while molar heat capacity is for one mole of the substance.
What is calorimetry?
An experimental method used to calculate the enthalpy change by measuring the mass and temperature change over time.
What is the formula for the enthalpy change per mole of a substance?
ΔH=q/1000/n
