AQA AS Chemistry Unit 2 Revision

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  • Created on: 18-04-13 16:58
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Ener
get
ics
What
i
s t
her
mo
chemi
str
y?
Thi
s
is
the
study
of
heat
changes
dur
ing
chemi
cal
r
eact
ions.
What
ar
e exot
her
mic
react
ions?
These
are
react
ions
that
gi
ve
out
heat
such
as
neut
ral
is
ing
an
aci
d wi
th
an
alkal
i.
What
ar
e endot
her
mic
react
ions?
These are react
ions which t
ake in heatf
rom t
hei
rs
u rr
oundi
ngs f
ore
xample t
he br
eakdown ofl
imest
one (
cal
ci
um
car
bo nat
e)
tol
ime(
cal
ci
um oxi
de)
andc
a r
bond
i
oxi
de.
A not
her
exampl
ei
sheat
ingb
luec
opper
sul
phat
ec
r
ystal
st
oma
ke
whit
e anhydr
ous
copper
sulphat
e.
CuSO4.
5H20
C uSO4
+5H2O i
s endot
her
mic
so
the
rever
se
dir
ect
ion
w oul
d be
exot
her
mic
How
does
ther
mo
chemi
str
y enabl
e us
to
compar
e t
he
eff
ici
ency
of
dif
fer
ent
f
uel
s?
Theoret
ical
chemist
sme
a sur
et
hee
nthal
pyo
f combusti
oni
nkJmo
l 1b
e causet
hi
sc omp ar
est
hes
amen umber
of
molecul
es f
or each
fuel
.
For
use as
fuel
s,
ene r
gy gi
ven out
per
gram of
f
uel
(t
he
energy densi
ty
of
a f
uel
) i
s more
import
ant
.
Pet
rol
stor
es si
gnif
icant
ly
mo re
energy
than
me t
hano l
or
ethanol
.
H ydr
ogenh a sav
e ryh
ighe
n er
gyd
e nsi
tya
nds
toresl
otso
f
en er
gyp
e r
gram but
gaseoush
ydrogent
akesu
pal
ot
of
space
an d
is
dif
fi
cult
t
o st
ore
eff
ici
entl
y.
What
i
s t
he
ent
hal
py
change
of
a sys
tem?
Thi
si
stheh
eat
energyc
hangea
t
constant
pr
essur
e. Chemist
so
ftenu
sef
l
askso
pent
ot hea
tmo spher
et
ome
asur
eh
eat
changes
meani
ng t
he
react
ion
is
carr
ied
out
at
atmospher
ic
pressur
e whi
ch
onl
y var
ies
sli
ghtl
y day
to
day.
What
ar
e t
he
standar
d condi
ti
ons
for
measur
ing
ent
hal
py
changes?
100kPa whi
ch
is
app r
oxi
ma t
ely
normal
at
mospher
ic
pressur
e.
298K/
2 5
degrees
w hi
ch
is
approxi
mat
ely
nor
ma l
room t
e mperat
ure
What
i
s t
he
standar
d st
ate
of
an
element
?
Thi
s
is
the
stat
e i
n whi
ch
the
element
exi
sts
at
298K
and
100KPa
What
does
the
ent
hal
py
level
di
agr
am
look
li
ke
for
an
exot
her
mic
react
ion?
Thep
roduct
se
n du
pw
i
thl
essh
eat
ener
gyt
hant
hes
tar
ti
ngma
teri
a l
sb
e causet
heyh
avel
ost
heat
ener
gyw
henh
eat
ingu
p
t
heir
sur
roundi
ngs
meani
ng
they
are
on
a l
ower
level
t
han
the
react
ants.
What
does
the
ent
hal
py
level
di
agr
am
look
li
ke
for
an
endot
her
mic
react
i
o n?
I
na
ne n dot
hermicr
eact
ion,
thep
roductse
ndu
pw
i t
hmo
r ee
nergyt
hat
t
hes
t
art
ingma
t
eri
alss
ot
hee
nt
hal
pyc
hangei
s
posi
ti
ve
and t
he pr
oduct
s are
on a
higher
l
evel
t
han
the
react
ant
s.
How
does
atmospher
ic
pressur
e af
fect
t
he
amount
of
heat
ener
gy
giv
e n
out
by
react
ions
that
i
nvol
ve
gasses?
I
fag
asi
sg
i veno
u t
, somee
n er
gyi
sr
e qui
redt
op
u sha
w ayt
hea
t mospher
ea
ndt
heg
r
eat
er
thea
t
mospher
ic
pr
essur
e,
the
mo re
energy i
s
used f
or
thi
s.
Thi
s
me ans
less
energy
rema i
ns
to
be gi
ven out
as
heat
by
the
react
ion
How
does
the
physi
cal
st
ate
of
the
react
ant
s and
product
s af
fect
t
he
ent
hal
py
change
of
a r
eact
ion?
Ther
ei
sagr
eat
er
negat
iv
ee nt
hal
pyc
hanget
ot
ur
nh
ydr
ogena
ndo
xygeng
asi
nt
ol
i
qui
dw
at
er
thant
ot
ur
ni
ti
nto
st
eam

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Page 2

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Thed
i
ff
erenceb
et
w eent
het
woe
nt
hal
pyc
hangesi
st
hea
mount
of
heat
neededt
ot
ur
no
nemo
l
eo
f
wat
er
int
o
st
eam
What
i
s t
he
standar
d mol
ar
ent
hal
py
of
for
mat
ion?
Thi
s is t
he ent
ha l
py change when one mo l
e ofc
omp ound i
s f
ormedf
r
om i
tsc
o nst
it
uente
lement
su
nders
tandar
d
condi
ti…read more

Page 3

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How
do
w e
all
ow f
or
heat
l
oss
on
a gr
aph?
Befor
et
hee
x per
ime nt
all
t
hea
p paratusa
n db
o t
hs
ol
uti
on sa
rel
eft
tos
tandi
nthel
aba
n dt
hise
nsurest
hat
theya
ll
r
each
the
sa me r
oo m temperatur
e .…read more

Page 4

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Page 5

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Page 6

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Thesea
r
emi
n eral
st
hat
havev
e r
yo
p enp
o r
es
t r
uctur
est
hat
ionso
r mol
ecul
esc
anf
i
t
int
o,
theyc
onf
inet
hemo
l
ecul
esi
n
smal
l
spaces
w hi
ch
causes
a change
in
thei
r
str
uctur
e and
react
ivi
ty.…read more

Page 7

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Thes
e ao
fd
e l
ocal
isede
lect
ronsg
etsf
urt
hera
w ayf
rom thep
o s
iti
ven
ucl
euse
acht
i
mea
n dt
her
ei
sa
lsod
ecr
easing
densi
tyo
f
char
geme
a ningt
her
ei
slessa
t
tr
acti
onf
or
thee
lect
ronsa
ndt
hes
t
rengt
ho
f
t
heme
t
all
i
cb
ondsd
ecr
eases
tar
ti
ng
wi
th
ca l
ci
um.…read more

Page 8

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I
t i
sa
lsou
s eda
sas
imp l
et
est
for
sul
phat
ei
onsi
ns
ol
uti
on.
T hes
ol
uti
oni
sfi
rst
aci
dif
i
e dw
ithn
i
tr
ica
ci
do
r
hydr
ochl
ori
c
aci
da
n dt
henb
a r
ium
chl
ori
des
o l
uti
oni
saddeda
ndi
fasulphat
ei
spresent
,
aw hi
tep
reci
pit
ateo
f
BaSO4i
sf
ormed.…read more

Page 9

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Vand
er waalsf
or
cesa
ret
heo
nl
y i
nter
molecul
ar
for
cess
ome
l
ti
nga
ndb
oi
li
ngp
oi
ntsi
ncr
easew
i
thc
hai
nl
engt
ha
ndt
hey
ar
e non
polar
so
they
are
insol
ubl
e i
n wat
er.
How
do
alkenes
react
?
Theya
remo
r er
eact
ivet
hana
lkanest
hought
heyh
a veah
igher
bonde
nt
hal
py.…read more

Page 10

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What
happens
w hen
the
doubl
e bond
is
n '
t
in
the
exact
mi
ddl
e of
t
he
chai
n?
Ther
ea
r et
wop
ossi
blep
r
oductsb
e causet
heh
y dr
ogenb
r
omi
dec
oul
db
ondt
oe
i
ther
of
t
hec
ar
bona
t
omso
f
t
hed
oubl
e
bond
e.g.
1
Bromopr
opane
or
2 Bromo propane.…read more

Comments

Peter

Pretty good, will help with revision :) thanks

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