Lecture notes
Chemical Energetics Chemistry A Level CIE
Chemical Energetics Chemistry A Level CIE
[Show more]
Seller
Follow
Content preview
192↳2=
E
↳
III
Lattice Energy Born Haber Cycles
bond breaking -
endothermic
bond formation - exothermic
· AH = ( -
>
bond formation > bond breaking
· DH = (t)
bond breaking > bond formation
standard enthalpy change of reaction enthalpy change when the amounts of reactants shown in the
:
stoichiometric equation react to give products under standard conditions
-standard enthalpy change of formation :
enthalpy change when one mole of a compound is formed
from its elements under standard conditions
e x
.
: 2 Fe(S) +
102(9) -> FezOzCS) BHf= H
cigraphites + 29(5) +> CS2(e) DHf=(H)
standard enthalpy change of combustion :
enthalpy change when one mole of a compound is burnt
in excess
250 290K
oxygen under standard conditions ,
1 atm
-standard enthalpy change of neutralisation :
enthalpy change when one mole of water is formed by
the reaction of an acid and alkali under standard conditions (always exothermic
-enthalpy change of atomisation
:
enthalpy change when one mole of gaseous atoms is formed from
its element under standard conditions & Must be endothermic labsorb solid -
gas)
,
LiCS) -> LiCg) BHat (H)
:
e x
.
=
C1219) -> C1 (g) DHat =
(H)
, Hatt= DHatmetal +
DHatNM +IEm + EANM
an ionic compound
Lattice Energy
:
enthalpy change when I mole of is formed from its gaseousions
under standard conditions
e x
.
:
Nat (g) +
C1-19) -> NaCICS) DHatt= -
+
Mg2 (g) +
2C1- (g) -
MgClz(S) DHlatt = If
2A13 30219) A1z03 (S)
+
19) + -
DHlatt= -
Mg2 (9) 02-(9) M90(S)
+
+
-> &Hatt= -)
·
Electron Affinity
the energy change when a gaseous non metal atom accepts one electron
-First electron affinity :
enthalpy change when I mole of electrons is added to I mole of gaseous atoms
to form one mole of gaseous 1-ions under standard conditions
-second electron affinity :
enthalpy change when I mole of electrons is added to I mole of gaseous--ions
to form one mole of gaseous 2-ions under standard conditions
First : subsequent :
Formation of bond -) and repel - need to supply energy to form
(->
subsequently , .
First exothermic , then endothermic :
Energy needs to be absorbed to overcome Electrostatic forces of
(t)
!
masukin energy ke
Attraction between negative charged electrons and negative ions
shell yg less energy
negatives
-
S(g) e S (9) 200 trend 1s+ EA down the group decrease cless
-
+
->
-
S
-
(9) 640
-
5-(9) e F
-
+ -
+
FC e
more energy
52 -(9) Cl
440
-
S(9) +
ze - +
Br masuk shell
larger
radius Cl
yg higher
I
-e- energy ,
We
I di release
* why Hat of Cl half of its bond energy (+244K)/MOl ↓ IeSS
weaker nuclear
E((219) -- (I(g) Attraction
I (4) So BHat =
+ 122 LE
=
BHF-DH1
I gaS LE =
DHF-(IDHqt+IDHatNM+IlEm +ZEANm)
Cl gas yellowish green Add e- to i not favourable,
there's repulsion , to overcome
Br liquid reddish-brown
the repulsion bond energy
I solid black (gas :
purple , liquid
:
dark browns
D Hat of He =
0K) /Mol
Element Always zero
Kr , Ar , etc
All noble gases ,
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 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 kathleenho. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for £8.26. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
50843 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy revision notes and other study material for 14 years now