Thermodynamics and kinetics Flashcards
What is an open system?
Can exchange matter and energy with its surroundings
What is a closed system?
Can exchange only energy with surroundings
What is an isolated system?
Can exchange neither energy nor matter with its surroundings
Define endothermic.
Requires/absorbs heat, delta H > 0, heat is a reactant
Define exothermic.
Heat released, delta H < 0, heat is a product
What does ‘q’ represent in thermodynamics?
Heat, energy absorbed or released
What is the specific heat capacity (c) value?
4.184
What does ΔH represent?
Energy absorbed or released
What does ΔHsol represent?
Energy absorbed or released per mol
What does ‘n’ represent in thermodynamics?
Moles
What does ‘mm’ stand for?
Molar mass
What does ‘C’ represent in a solution?
Concentration
What does ‘V’ represent?
Volume
What are the types of enthalpy changes?
- Physical
- Chemical
- Nuclear
What is a physical enthalpy change?
Least amount of enthalpy change, involves changes of states or dissolving
What is a chemical enthalpy change?
Mid-range enthalpy change, involves overcoming chemical structure and bonds
What is a nuclear enthalpy change?
Highest enthalpy change, involves splitting atoms and overcoming forces between protons and neutrons
What does ΔHx represent?
Energy change associated with one mole of substance
What is the standard enthalpy of formation?
Enthalpy change at SATP where a mole of a compound is formed from its elements
What method is used to find ΔH for reactions?
Hess’s law or sum method
What is the rate of reaction (RR)?
The speed with which reactants disappear and products form
How can we tell if a reaction has occurred?
- Change in colour
- Heat production or loss
- Bubbles
- Precipitate formation
- Change in pH
How is the measurement of the rate of reaction calculated?
Δconcentration/time(s)
What factors affect the rate of change?
- Concentration
- Surface area
- Temperature
- Catalyst
- Nature of substance
What is the relationship represented by ΔH?
ΔH = Hfinal - Hinitial
