Thermochemistry Flashcards
calorie (cal)
The amount of energy required to raise one gram of water by 1 degree celsius. (or 1 kelvin)
Calorie
Commonly used in quantifying food energy content. also known as a kilocalorie
Joule (J)
The amount of energy used when a force of 1 newton moves an object 1 meter.
1 calorie = ?
= 4.184 joules
Heat capacity (C)
The amount of heat (q) a body of matter absorbs or releases when it experiences a temperature change (ΔT) of 1 °C (or 1 kelvin)
Heat capacity equation
C=q/ΔT
What sort of property is heat capacity?
Extensive property — Depends on the size of the substance
Specific heat capacity (c)
the quantity of heat required to raise the temperature of 1 gram of a substance by 1 °C (or 1 kelvin)
What type of property is specific heat capacity?
Intensive property — It only depends on the identity of the substance, not the amount.
equation for the amount of heat (q) entering or leaving a substance
q= (c)(m)(ΔT) . Delta T means the initial temperature (Ti) is subtracted from the final temperature (Tf)
If a substance gains thermal energy (Tf>Ti), then the value of q is
Positive
If a substance loses thermal energy (Tf<Ti), then the value of q is
negative
Calorimetry
Used to measure the amount of heat transferred to or from a substance
System
The substance of substances undergoing the chemical or physical change
Surroundings
All other matter, including components of the measurement apparatus, that serve to either provide heat to the system or absorb heat from the system
Thermochemistry
The study of heat absorbed or released during chemical and physical changes
Thermal Energy
A type of kinetic energy (KE) associated with the random motion of atoms and molecules
Temperature
The quantitative measure of hot or cold
Fast Moving molecules mean—>
High thermal energy giving a “hot” temperature
Slow moving molecules mean —>
Low thermal energy giving a “cold” temperature
Heat
Also abbreviated as (q). Is the transfer of thermal energy between two bodies at different temperatures
Heat Flow
This increases the thermal energy of one body and decreases the thermal energy of the other
How long will thermal energy flow from one body to another?
When two substances are placed in contact, thermal energy will always flow from a high temperature substance to the low temperature substance until both substances are at the same temperature.
Exothermic process
A change that releases heat (heat is exiting the substance)
Endothermic process
A change that absorbs heat (en like in because heat is going into the substance)
