Summary
Summary chemistry chapter 13: Thermodynamics
- Course
- Institution
This is a good summary with all the information you need to know about thermodynamics!
[Show more]
Seller
Follow
samenvattingenvanmeike
Reviews received
Content preview
CHAPTER 13 - THERMOCHEMISTRYSystems:
- Isolated: no exchange energy/matter from system with surrounding
- Closed: fixed amount of matter, exchange energy possible
- Open: both matter and energy can be exchanged with surrounding
Heat capacity(C) is the heat needed to raise the temperature of a substance by 1K.
Specific heat capacity Cs is for 1 gram substance.
q
Cs=
m∗dT
Molar heat capacity is of 1 mol:
q
C m=
n∗dT
Value of molar heat capacity depends for gases on if the experiment is carried out under
constant pressure or volume Cp/Cv
Heat capacities are intensive properties of substances: don’t depend on quantity
substances. (extensive properties do depend).
Enthalpy change: dH is heat transferred at constant pressure by chemical
reaction/process. It’s a state function: only depends on current state system, not how it
got there. dX=Xfinal-Xinitial.
Standard enthalpy change of fusion: dfusH: energy to melt 1 mol substance at
melting point at 1 bar. dvapH at boiling point. dfusH<dvapH.
Sublimation: solid goes directly to gas: dsubH=dfusH+dvapH
Hess’s law: the total enthalpy change for a chemical
reaction is independent of the path by which the reaction
occurs, provided the starting and finishing states are the
same for each reaction path.
Standard enthalpy change of formation: 1 mol compound
formed under standard conditions from elements in standard
states. Enthalpy of formation for element in standard
state=0. Standard state= most stable form
elements under standard conditions.
, Vi is stoichiometric coefficient: number of moles of reactant of product involved in
balanced thermochemical equation.
Standard enthalpy change of combustion dcH: heat released when substance burns at
constant pressure a.k.a. the heat of combustion. Variation of dcH: energy desity or
enthalpy change per unit mass of a compound in units kJ(or MJ)/g = enthalpy change on
burning 1 (k)g of compound.
Standard enthalpy change of a solution dsolH: when 1 mol substance dissolves in
large excess pure solvent at 1 bar, a.k.a. integral enthalpy change of solution.
Bond dissociation enthalpy D(A-B): enthalpy change per mol when particular
chemical bond, A-B, is broken under standard conditions in the gas phase.
Different quantities of energy needed to break
each bond because of the different electron
densities in the particular C-H bonds. The
mean bond enthalpy is the average of the
bond dissociation enthalpies.
These mean bond enthalpies are
approximated values calculated from a large
number of compounds.
Enthalpies of substances increase when the temperature increases. Enthalpy change =
heat transferred at constant pressure. If qp is energy used to heat substance in open
container from T1 to T2, enthalpy change is:
dH T 1→ T 2=H T 2−H T 1 =q p
P stands for constant pressure. dH is an enthalpy change of a substance when
temperature is raised form initial to final temperature, not an enthalpy change of a
reaction (like before).
qp
Cm , p= , so qp=Cp∗n∗dT =dH T 1 →T 2=H T 2 −H T 1, so for 1 mol:
n∗dT
qp=Cp∗dT =dH T 1 → T 2=H T 2−H T 1, so H T 2 =H T 1 +Cp∗dT
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller samenvattingenvanmeike. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $8.10. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
56326 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now