unit chemistry 12 [k£'1 i worksheet 2-1 - equilibrium...
TRANSCRIPT
Chemistry 12
Chemistry 12Worksheet 2-1 - Equilibrium, Enthal~
and EntroQY
Unit 2 - Chemical Equilibrium
[K£'1 I1. What do people mean when they say that a reaction is reversible? +hJL r e.a t.... {~()t1
L~_~.A\t9D {f\ +~IL fcv W 6t r) Or' (~V~v~ JL;. fee h DVl .
2. Give four things which are true about a system at equilibrium:
1.
3.
2. ........LJ 0 m it (I'D $ (D)O,"C_ c~..C( (\ {1L {, v.s~/6.k;rn cLb~:l'd k~p / <;. W(/~'f-~1t1~\J '
4. E Cf:}M' 1 ) bvtv) (tvn b-< t;vPl21&a cl,-?t\
What is meant by macroscopic properties? 010 $..< V V ,1- b)0
rpvop~v-h~s (~: C.7-.}OlAV") PVJS~lAV<,
Give some examples of macroscopic properties: c:b I au ;f I ,Pr-L \ <:; u., #'.e/
l+'-DVV/ I-e.ff ornOM'
cUf/l S i'J-,Yl ~'''f)4.
~~J~~)_k~,~~_' _5. What happens to macroscopic properties at equilibrium?_--J...-'Al~D~--=0_lv__ ~--!J. --""",,,-' _
( r..t..W\ t{.." n LbYl ~ t CL;'" I- J '6. How do the rates of the forward and reverse reaction compare at equilibrium? --1~ff
tLv.e. ..L& ~J .
7. Do the forward and reverse reactions stop at equilibrium?_........L../v_'_O_. _
8. What can be said about the concentrations of all reactants and products at equilibrium?
9. Why is chemical equilibrium called dynamic equilibrium? d. ~"l'\ tt ItVl i Ll'V\..i-.tt-ns "ektt-VI g'I·~r 5v 'frv,Dv'/~ ;1" -get' (.1- CiY/H
ch~ it {UvTJ duel" Cl.,~ v,'c<.. V-e.V{ ~ .f
Worksheet 2-1 - Equilibrium, Enthalpy and Entropy Pagel
Chemistry 12 Unit 2 - Chemical Equilibrium
10. Given sufficient activation energy, a system not at equilibrium will eventually move toward~ (A.A' } ,'Iv vr//...Co/L .
11. Systems will tend toward a position of tv\"n /'mum (low) enthalpy.>
12. Systems will tend toward a position of MIt)(,' 'M IA. m ( h (j" ) entropy.
13. Tell whether each of the following is endothermic or exothermic and state which hasminimum enthalpy, the reactants or the products:
a. Cb(g) + PCb (g) ( ) PC15(g) MI = -92.5 kJ
EX 0 thermic and the p t-o J.,lA.- L h have minimum enthalpy.
bD 2NH3(g) E) N2(g) + 3H2(g) All = 92.4 kJ
8NO 0 thermic and the r e.. iL L+- tIll t~ have minimum enthalpy.
~t+
~Iii~cD CI4(g) + H20(g) + 49.3 kJ ( •• CO(g) + 3H2(g)
8/J 00 thermic and the r -e..a.e.t- Ct (l +_.( have minimum enthalpy.
E;NJ)O. -__ 51(~·All = +25 kJ14. If the reaction: Ch(aq) (.. Ch(g)tfD ,'w lL.r-.A )
was proceeding to the right, the enthalpy would be _LJ !-(\.:......=:~:::::..:V~-l.i.=..:.....7L._!_--'ing. Is this a
favourable change? Iv D
15. If the reaction: N2(g) + 3H2(g) <' 2NH3(g) + 92.4 kJ E)(0 .~
was proceeding to the right, the enthalpy would be eLL L V..e. Ct $ ing. Is this a
favourable change? "I e-~
Worksheet 2-1 - Equilibrium, Enthalpy and Entropy Page 2
Chemistry 12 Unit 2 - Chemical Equilibrium16. For each of the following, decide whether the reactants or the products have greater entropy:
a) l2(s) E 0) h(g) The rp u-o d i..-L["f' ~ have greater entropy. R.i.tfl.£lDWl/~( ~,V 11'\ 05· I /'Vi.OJ ,
b) 4PH3(g) E 0) P4(g) + 6H2(g)
__ -----'-- ----'---- --'have greater entropy.
17. When the two tendencies oppose each other (one favours reactants, the other favours
products), the reaction will ( -l"tc(h (:1 6. I-t"-t k of -l.Ll UA"i J " ~'u t4A
IProcesses in which both the tendency toward minimum enthalpy and toward maximum
entropy favour the products, will --1@g.' --v~_.J..h...;..._..;:w;;....;;;...;..VV1...:...;;_Ifl.,;"",l,/....;--f-;;;..t'-·'l ••• ..;.,U...;,I_1_, _
Processes in which both the tendency toward minimum enthalpy and toward maximum
entropy favour the reactants, will __ 11••••.'o-..;.'t- c_/_L.._' _' Ct..--v_'- __ 1--'_--=cd- tvL(._' __ . _
18. F or each ofthe following reactions decide which has minimum enthalpy (reactantsor products),which has maximum entropy (reactantsorproducts), and if the reactants are mixed, what willhappen? (go to completion!reacha stateof equilibrium/notoccurat all).
~ TY\O.9 '-f m O~ /.:a) 4HCl(g) + OZ(g) E 0) 2HZO(g) 0+ 2CIZ(g) + 114.4 kJ \Ex b ')
The -Ip"--'r--tJ---'-_' _cl_S-__ . have minimum enthalpy.
IThe __ ---=-r_~....::e.='".c_~_' .!-1-_' ....::.~'--_. have maximum entropy.
IfHCl + 02 are put together, what should happen?(go to completion!reacha stateofequilibrium/notoccurat all) .) "b ~! . ,rA-.fL Lk 4L..U I', V V IA.....vV\.,
'J- M 0 ~ 'J- j'Vl °5 G "-C02(g) + H2(g) E " CO(g) + H20(g); MI = 42.6 kJ .BNDO )
The r-L,u c J- (:1.- rl J-s. have minimum enthalpy. L ' L. /,~ ~n 0 Dv...---,-o-How does the entropy of the reactants and products compare? S eLi/VI L "/'/1 Ll"'lf.o/~/IfC02(g) +0 H2(g) were put in a flask, what should happen?
(go to completion!reacha stateof equilibrium/notoccurat allno· - 0L (.-u...,.v- 0 V- . L ,I, . 1'1 I r-t..Li...( t-- .
b)
Worksheet 2-1- Equilibrium, Enthalpy and Entropy Page 3
Chemistry 12i-frnoQ' ~,
c) 4PH3(g) E > P4(s) +rYI 0.s6H2(g) + 37 kJ
Unit 2 - Chemical Equilibrium
~y--o)
The ,D"",,' ,--,0),-=--",~:..;:, =--._L..:...../-..:;..$'._, has/have minimum enthalpy,(
The .q:.p~o_-tJ=_).::..cL__.:.· _0_1._L-.-:f:.-.-· ~...:......... has/have maximum entropy,
IfPH3(g) was put in a flask, what should happen?(go tocompletion!reacha stateofequilibrium/not occuratall)
19. Do systems always reach minimum enthalpy at equilibrium? 11 a '-~--------Explain. -rfL12- 4~fV;f!..i/J CtJ ,(Pr- IY1-Cv%' .e11 hPU pi) au
I
20. Do systems always reach maximum entropy at equilibrium? /1,,0.I -~--------
Explain. 1ivL -I~vlc~t LtJ~V' fY\-.L;"-..I, ~..j h aAf(j21. A "heat term" in a chemical equation shows what is happening to the
M t'--'t) k 0JOjIP () S: i .~)'\ v
.£l rvl/~(j=- ~H)and really has nothing to do with the(Answers are either entropy or enthalpy)
22. As a reaction approaches equilibrium, the rate of the forward reaction1
while the rate of the reverse reaction ----')'--'f1'-'--""'c'-",r--"'~~.e=(_c::;:""'.1=,'__. ~",-" _
Once equilibrium is reached, the rates become __ ---.:::C::....·-.-:&=-· _lA_,. _l4_'_l- _
23. Consider the reaction: BaC03(s) + heat E " BaO(s) + C02(g)
Which one of the following observations will indicate that the reaction has most likelyachieved equilibrium?
/ (' j 11 J .., . Irl r- I uf LrL.' f . a-..' ivM, ,+/A.,'/l(,a-) The mass of the system becomes constant ,,'-I-vi 5 t~·2. c , •..f)' , . '.' 1 '. (/') .J
l?Y The concentration ofBaO(s) becomes constant i v'I.. t)1. c/ D ~.<..t'(, S C) '" J..L.jA;. .
.~ All the BaCO~ is consumed.(dL:Jhe gas pressure (or concentration of gas) of the system becomes constant
Your answer is oi . . Explain why. fr.~.[.'$ L.0y--e t $ Cl. lYt Cl DYe) 'SCOJOt C{2LQ ,ae.'IC~ .~~L -fil.J..., P (--t. t <; U. v~.. p r ,r:CI?~J WI' I I b.z.
(A)VlS t- tt>Vvt--· o..t .L-&"j v--t.. II b v\.. L-L ~
24. Consider the following reaction: Fe3+caq)+0 SCN-(aq) E " FeSCN2+(aq)
A solution ofFe(N03)3 is added to a solution ofKSCN. As equilibrium is being established,the [Fe3+]is d.£(ve~a.~/'~ and the [FeSCN2+] J'oev..e..cl{,"r:j .