T-1 Nature of Energy Flashcards
Describe how energy is stored within a chemical system
- In the motion of the particles within the system
- In the position of particles that are attracted to or repelled from each other (Intermolecular attractions)
- In the positions of the atoms/ions within a chemical species (intramolecular attractions - chemical bonds)
What is chemical energy?
Energy stored in the positions of the atoms/ions within a chemical species (intramolecular attractions - chemical bonds)
What is thermal energy?
Energy stored in the motion of the particles within the system
What is phase energy?
Energy stored in the position of particles that are attracted to or repelled from each other (Intermolecular attractions)
What factors impact the amount of energy stored in a system, thermally - thermal energy?
1) average velocity of the particles - temperature
2) Number of particles in the system - mass
What factors impact the amount of phase energy stored in a system?
1) Strength of interaction between the particles - some constant
2) Number of particles in the system - mass
What factors impact the amount of chemical energy stored in a system?
1) Strength of interactions within the molecules - some set of constants
2) Number of particles in the system - mass
List three way to transfer energy into or out of a system
- Heating (heat)
- Working (work)
- Radiating
Describe the process of heating.
Fast moving particles collide with slow moving particles. Slow moving particles speed up while fast moving particles slow down. This continues throughout the substance until themal equilibrium is reached.
Describe the conditions that must be met in order for heating to occur.
There must be a difference in temperature
What is thermal equilibrium?
Temperature of two substances/regions is the same. At this point there is no net trasnfer of energy through heating.
What type of work will we consider in chemistry?
Expansion or contraction of a gas at constant pressure.
Is the following process exothermic or endothermic
- A + B → C + energy
Exothermic
Is the following process exothermic or endothermic
- A + B + energy → C
Endothermic
Is the following process exothermic or endothermic
- A + B → C delta H is positive
Endothermic
Is the following process exothermic or endothermic
- A + B → C delta H is negative
Exothermic
Is the following process exothermic or endothermic
- Surroundings grow warm during the process
Exothermic
Is the following process exothermic or endothermic
- Surroundings cool during the process
Endothermic
Is the following process exothermic or endothermic
- Energy is brought into the system from the surroundings
Endothermic
Is the following process exothermic or endothermic
- Energy is released from the system to the surroundings
Exothermic
Is the following process exothermic or endothermic
- Energy is released from the system to the surroundings
Exothermic
Is the following process exothermic or endothermic
- A gas expands at a constant pressure
Exothermic
Is the following process exothermic or endothermic
- A gas contracts at a constant pressure
Endothermic
Is the following process exothermic or endothermic
- A gas expands at a constant pressure
Exothermic
Is the following process exothermic or endothermic
- A gold bar melts
Endothermic
Is the following process exothermic or endothermic
- Sweat evaporates
Endothermic
Is the following process exothermic or endothermic
- Water freezes
Exothermic
Is the following process exothermic or endothermic
- steam condenses
Exothermic
Heat of Solution
Enthalpy change associated with dissolving a solute in a solvent at a constant pressure
Heat of Vaporization
Energy required to change a certain amount of a liquid into a gas.
Heat of Fusion
Energy required to change certain amount of a solid into a liquid
Specific heat capacity
Amount of energy required to change the temperature of 1 gram of a substance by 1 degree Celcius
molar heat capacity
Amount of energy required to change the temperature of 1 mole of a substance by 1 degree Celcius
Enthalpy change associated with dissolving a solute in a solvent at a constant pressure
Heat of Solution
Energy required to change a certain amount of a liquid into a gas.
Heat of Vaporization
Energy required to change certain amount of a solid into a liquid
Heat of Fusion
Amount of energy required to change the temperature of 1 gram of a substance by 1 degree Celcius
Specific heat capacity
Amount of energy required to change the temperature of 1 mole of a substance by 1 degree Celcius
molar heat capacity
Equation for work of gaseous expansion or contraction
w = -P•(Vf-Vi) where P is atmospheric pressure in atm
Equation for heating that occurs when a substance changes temperature
q = m•c•(Tf-Ti) where c is specific heat capacity of the substance
Equation for the heating that occurs during a phase change
q = m•Hphase change where Hphase change is Hvap, Hfus, Hsub, etc…