The Nature of Energy
What is energy commonly defined as?
The capacity to do work or transfer heat.
What does the first law of thermodynamics state?
Energy can be neither created nor destroyed.
What is enthalpy (H)?
The internal energy plus the product of the pressure and volume of the system.
What is calorimetry used to measure?
Heat changes in chemical processes.
What does Hess's Law state?
The enthalpy change of a total reaction is the sum of the enthalpy changes of its individual steps.
What type of energy is associated with the motion of an object?
Kinetic energy.
What is the internal energy of a system?
The sum of all the kinetic and potential energies of the components of the system.
What is the formula for the change in enthalpy (ΔH) at constant pressure?
ΔH=ΔE+PΔV
What is the heat capacity of an object?
The amount of heat required to raise its temperature by 1 degree Celsius.
What is the standard enthalpy of formation?
The change in enthalpy when one mole of a substance is formed from its elements in their standard states.
What type of energy is associated with the position of an object relative to other objects?
Potential energy.
What is the formula for the change in internal energy (ΔE)?
ΔE=Efinal−Einitial
What does a positive ΔH indicate?
The process is endothermic (heat is absorbed).
What is the formula for calculating heat (q)?
q=m⋅c⋅ΔT
What is the standard state of an element?
The form in which the element exists under standard conditions (1 atm pressure and 25°C).
What is the SI unit for energy?
Joule (J).
What are the two main ways energy can be transferred?
As work and as heat.
What does a negative ΔH indicate?
The process is exothermic (heat is released).
What is the specific heat capacity?
The amount of heat required to raise the temperature of 1 gram of a substance by 1 degree Celsius.
How do you calculate the enthalpy change of a reaction using standard enthalpies of formation?
ΔHreaction=∑ΔHf(products)−∑ΔHf(reactants)
What is the formula for calculating kinetic energy?
Kinetic Energy=1/2mv2
How is the change in internal energy related to heat and work?
ΔE=q+w
How is enthalpy change (ΔH) related to heat at constant pressure?
ΔH=qp
What is a bomb calorimeter used for?
Measuring the heat of combustion of a substance.
What is the enthalpy change for the reaction if the enthalpies of formation for the reactants and products are given?
Use the formula ΔH(reaction) = ∑ΔHf(products) − ∑ΔHf(reactants)