Thermochemistry Flashcards
Explain Potential energy changes regarding enthalpy.
Potiential Energy change is when the ethalpy of a substance changes due to a phase change. (Breaking inter or intramolecular bonds)
change in ethalpy= (moles)(molar enthalpy of the process)
If change in Enthalpy is - that means the reaction is exothermic. Because the system is loosing enthalpy>
What is the equations for mesuring change is kenetic energy of a system?
Q=mc(Tfinal-Tinitial)
Molecules are speeding up due to change of energy is the system. If Temperature intial is greater than temp final you will get a negative q. Meaning loss of enthalpy in that system.
What is molar enthalpy?
Molar enthalpy is the amount of energy absorbed or released per mole of substance through different types of reactions
- reaction
- combustion
- neutrlization
- fusion
- formation
If Molar enthalpy is +. Engery is added (adsorbed)(endothermic). If - energy is removed (released) (exothermic).
What are the assumbtions of a calorimeter?
What are some tricks of calioimeter calculation?
When adding a solution to another solution. The final mixture you must add the masses together.
ELost= - Egained
What makes the molar enthalpy of a proccess positive or negative.
Breaking of bonds and forming bonds
What makes a compound more stable?
Compounds with lower molar enthapy formation are more stable. Because The more energy relased during the formation (-) the stronger the bonds are of the molecule and the more energy that would be required to break them.
What are the ways to express enthalpy change in an equation?
what are the units for molar enthalpy and the symbol?
H= molar enthalpy (KJ/mol)
n=moles
DeltaH=Enthalpy change (KJ)
DeltaH=nH
Explain what enthalpy of formation is relative to chemical equations?
Depending on the compound that the enthalpy of formation is for. It described how much energy it takes for 1 mole of that compound. SO if you are asked how much energy is required for a forming element. writing out the chemical equation and balancing it is key. This will show you how much energy is required depening on the ratio of all the elements in that reaction.
How would you find the enthalpy change for a building element of a formation reaction.
- Find the compound in the formation table
- Write chemical equation
- Balance equation
- Reduce ratios so that the compound has a ratio of 1 (because that is what the value heat of formation is relating to KJ/(mole of the compound)
- make a proportions equation and solve
Explain hess Law
Explain hess’s law
Explain how you would do a hess law equation using H of formation
Explain a hess laaw equation using the additive method
For a reaction to occer what must happen
What is catalysts (enzyme)?
What is Activation Energy
What is an activating complex?
