NAME: Ihl4tUU

PERIOD:

Chapter 6 Review

1. Two gases, A(g) and B(g), are confined in a cylinder-and-piston arrangement. Substances A and B reactto form a solid product:

A(g) + B(g) -+ C(s)

As the reaction occurs, the system loses 1150.0J of heat to the surroundings. The piston moves downwardas the gases react to form the solid. As the volume of the gas decreases under the constant pressure of theatmosphere, the surroundings do 480.0J of work on the system. Determine the change in the internalenergy of the system.

- / I SO , 0 .::T

3 -t ur-

(-IISO.OJ") -I ('1ro.O:r)

2. Calculate the change in the internal energy of the system for a process in which the system absorbs140.0J ofheat from the surroundings and does 85.01 of work on the surroundings.

tV ~ - ffs.Q .:::r

.::- (1'10.0 J) + (-RS.o:::r)

:: IS~. 0 :r I

IIJO.o .:r

3. Calculate 6E, and determine whether the process is endothermic or exothermic for the following cases:

a. A system absorbs 85.0kJ of heat from its surroundings while doing 29.0k1 of work on the surroundings.z: g s , 0 Jc....r- LV'::- -,;J. 9, 0 .lc..r:

'b I.> E = ~. W- s: (~s. 0 -J.<.T) + (- ~9.0 .lcJ) :

b. q = 1.50kJ and w = -657.0J

t:.~ s: b"HV's: (I. S0-kr) -I- ( - • " ;S 7 Jc:J) : \L-O~.~p_~_~_jc_J__ .:_:2_<t_3-;-.o_J__ l

.Lvt.d.,c. The system releases 57.5kJ of heat while doing 13.5kJ of work on the surroundings.

~:: -SI.S.k.:r IN:- -I3.$L.T'

,~t:':; b 1" lV .: ( - '5.1. S Je..T) -t ( - J a. s )<:..3) s: t -7/. 0 k.r 1h.;o.

OVER

4. At one time. a common means of forming small quantities of oxygen gas in the laboratory was to heatKCIO):

2 KCIO) (s) --+ 2 KCI (5) + 3 02 (g) ilH = -89.4 kJ /f·\

For this reaction, calculate ~H for the formation of

a. 0.855 mol of 02

.SSS n-(ci o~=

I

b. 1O.75g ofKCl

..l.J- = 10. lSj J(ClI

I",,-rR 1<LI74. S.Sj KCJ

j~6~ ) ( q1.0 - Ql~. 0)

(,t;. tf ~~J5b. Determine the molar heat capacity of water.

C Ii· .: (tf.fa -L-)( I~, 02J) __"'~ J~ /...•.,.1.

6a. Large beds of rocks are used in some solar heated homes to store heat. Assume that the specific heat ofthe rocks is 0.82 J/g°C. Calculate the quantity of heat absorbed by 50.0kg of rocks if their temperatureincreases by 12.0vC.

6b. Calculate the temperature change these rocks would undergo if they emitted 450.0kJ of heat.

z s:

_ t..I SO ClOO s: ( 50000) (. g 2.) £::)-r

_ 1.\ S.OOQO - =(.i l-){ .$0000\

7. The specific heat of iron metal is 0,450 J/gliC. Determine the amount of heat necessary to raise thetemperature of 1.05 kg block of iron from 25.0oC to 88.5°C.

~: n<lC61

::: (10 S0.5 ) (. q ~ 0

:; 3000.3.? S .r~ )(88'.S-~S.O)jC

z: 1"0.0~:r!

8. When a 9.55g sample of sodium hydroxide dissolves in IOO.Ogof water in a coffee cup calorimeter, thetemperature rises from 23.6°C to 47,4°C. Calculate L-.H. in kJ, for the solution process. Assume the.specific heat of the solution is the same as that for water.

NaOH (s) -. Na" (aq) + OH- (aq)

1> ~ - me 6.-r= (I01U$~) (</.,2 j~) (17.</ - .;lj,/,)

: - lo~q2'. tll~d. -J"

z

OVER

9. When a student mixes 50.0 mL of I.OM HCI and 50.0 rnl, of I.OM NaOH in a coffee cup calorimeter,the temperature of the resultant solution increases from 21.0oC to 27.5°C. Calculate the enthalpy changefor the reaction in kllmol HC!. assuming that the calorimeter loses only a negligible quantity of heat, thatthe total volume of the solution is 100.0 mL, that its density is 1.00 g/rnl., and that its specific heat is 4.18J/g0C.

HCI (aq) + NaOH (aq) -+ H20 (I) -i- NaCI (aq)

/Yl~ .: (/00"" L) (1.00 ~L.) =6 xo'IH EQ.m Ic, R..X,.J

a.l~v(-~~H .: (;'

mrrl. l-IeJ .: (.0 SL) ( /. 0 ~) : .os~D; -(1;1 Cu r zr.:: - (/~) (<-1.,2 j0e.)( ;)7. S - .J/. U )

.:: -~7/7J

- d7t7=

: (-StJ.3. %~]10. A 1.800 g sample of phenol (C6H;OH) was burned in a bomb calorimeter whose total heat capacity is11.66 kl/°C. The temperature of the calorimeter plus contents increased from 21.360C to 26.370C.

(a). Write a balanced chemical equation for the bomb calorimeter reaction.

(b). Determine the heat of combustion per gram of phenol.6:; - Cc..O ~ r;:; - (11.(,1, k.Xc..) ('2.(,.37 -~,.~'"'> .;

- :s~.4'''<' Jc.J'I g-00-1

II. Under constant volume conditions the heat of combustion of glucose (C6HJ206) is 15.57 kJ/g. A2.500g sample of glucose is burned in a bomb calorimeter. The temperature of the calorimeter increasedfrom 20.550C to 23 .25QC. Determine the total heat capacity of the calorimeter.

CJ (~~, ~S - 070, S S )

k:r:; 14,tfJ - \

o~ \-_.__ ...__ ._ ....._.__ ....._-_.\

10.---------- ---

f-l-

12. Under constant volume conditions, the heat of combustion of benzoic acid (HC7H,02) is 26.38 kJ/g. A1.640 g sample of benzoic acid is burned in a bomb calorimeter. The temperature of the calorimeterincreases from 22.250C to 27.20°C.

_ I.~t/Oj j_4ii" Ji'.IIc..r(a) Determine the total heat capacity of the calorimeter. .Ik J ;: - ::. 1/ 3. 2~ .3. l.

f 's

(b) A 1.320g sample of a new organic substance is combusted in the same calorimeter. The temperature ofthe calorimeter increases from 22.14oC to 26.82°C. Determine the heat of combustion per gram of the newsubstance.

%= - e~~-r~ _ (~,'JtI _-k~ )(o/t..t:l- ,,",,;),/l.t)::. - 4(). 9aa a8·1aif ..k.J

,. 10. qo J3i 90 1"k:r~ j:A.4,"W{ =I.3l0.J

:

13. Calculate the enthalpy change for the reaction

Given the following enthalpies of reaction:

p~ (s) +3 O2 (g)"--+ P~06 (s) 6H=-1640.1 kJ

P~ (5) + 5 O2 (g) --+ P~OIO(5) 6H = -2940.1 kJ

J: ~P,., 0'0 b. H : - iJ '1 '-fo, / .k.r:+ %'Od ~7

Py 0 y -,~

of- 3()~ 6H s: It; 'la, / .e r:/

------.~-.."----....;.--~------~ H:. -,300.0 .kr:

OVER

14. Calculate the heat of reaction for

Given the following enthalpies of reaction:

:2 H2 (g) + O2 (g) -+ 2 H20 (g) ~H = -483,6 kJ

3 O2 (g) -+ 2 03 (g) c"H = 284.6 kJ

s 3 3 3- '" '¥ Ha + L 0,; -7 2i{ I-Ia. 0;JI '%.I ~ 03Ol X ~ ~ O~

15. From the enthalpies of reaction

H2 (g) + F2 (g) -+ 2 HF (g) 6H = -537.0 kJ

c (s) + 2 F2 (g) -+ CF4 (g)

2 C (5) + 2 H2 (g) -+ CZH4 (g)

~H = -680.0 kJ

~H = 52.3 kJ

Calculate tlH for the reaction of ethylene with F2

C 2 1-1y -"f J c...f 02 f./.J~ X ~ C. f 'I~ r.;l -7 ~c..;:::,-/

.. _-_ ..... _--

6 f/ z - .s ~. 3 ..k:r

61-1 : - ~ 2'0,0 Jc.:r(z.)

~ ~ -= - $31. D.t:r (~)

6~ - a l/R',.3 J-:r-.3

s: ~. tI? X 10 ):.J

._--- ._- _ •..__ ....

16. The standard enthalpy change for the reaction

CaCO) (5) -. CaO (s) + C02 (g)

Is 178.1 kJ. From the values for the standard enthalpies of formation of CaO (s) and C02 (g) given inAppendix 4. calculate the standard enthalpy of formation of CaCO) (s).

(- 3 q 3. s) J - ~~.; Ct CO~

; [(-('3~)" (-3'1"3.S)J -Ilg./

) ~~I I- Iao s . ~ ~NL-

11g.1 z: [(-(,3S) <l-

e~ J-\.f ~L03

17. Given the following standard enthalpy change, use the standard enthalpies of formation provided tocalculate the standard enthalpy of formation of CuO (5).

CuO (s) + H2(g) -. Cu (5) + H20 (I)

~Hr H2 = 0 tiHr Cu = 0 tiHr H20(I) = ·286 kl/rnol

- '~«l.1 = [(0) + (-aa-f,)] - [(0)" ~ Hf ct.O]!) ~ / Cu. 0 ~ ( - a 9-~) - (- I ~ q. 1) ::. \,........--,-~G,-.-3-.k-:---~-J

j . Ill"'"

18. Using values from Appendix 4, calculate the standard enthalpy change for each of the followingreactions:

(b) Mg(OHh (5) -> MgO (5) + H20 (I)

o [ ] r f'I )] Ii ~1 ~J? A.lc.H"?'1l :;(-(,O~)f (-doff,) - (-l~S :. l"" /~,...,__

(c) CH4 (g) + 4 Cb (g) -> CCI4 (I) + 4 HCI (g)

b i-I~" "['j( -1~h (-IH) J - L (-1' ) > 'I (.)] , 1- <(.;)J' ¥J(d) SiCI4 (I) + 2 H20 (I) -> Si02 (5) + 4 HCI (g)

~~~"l1 .: [(-ql/) + 1I(-t;2.)] - [(-(,21) ~ d(-2f~)J

s: f-~o ~JOVER