awal kompre tugas 2

8/8/2019 awal kompre tugas 2

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1. For the reaction: pA + qBp rC + sDa. W hat is the reaction rate of A or vA b. W hat is the reaction rate of B or vB c. W hat is the reaction rate of C or vC d. W hat is the reaction rate of D or vD e. W hat is the relationship between vA, vB, vC and vD?

Answer:a. vA=

b. vB=

c. vC=

d. vD=

e. v = 2. Volumeof container is 10 L; at that container 4 gram of SO3 is decomposed to SO2 and O2. After 15 sthere are 1 gram SO3.a. W hat is the rate of decomposition SO3? b. W hat is the rate of formation of SO2?c. W hat is the rate of formation of O2?Answer:

2SO3 2SO2 + O2 i 0.05mol - -r 0.0375mol 0.0375mol 0.01875mole 0.0125 0.0375mol 0.08175 mol


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3.

a. K inetically, how can reaction be progress? b. Mention the factors that influenced the reaction rate! How is influence that given, thus th

reaction rate is changed?Answer:

c. For a reaction to occur, molecules, atoms, or ions must first collide. However, not acollisions result in reaction only effective collisions. For a collision to be effective, threacting species must (1) possess at least a certain minimum energy necessary to rearranouter electrons in breaking bonds and forming new ones and (2) have the proporientations toward one another at the time of collision.

a. Basically, reaction rate is influenced by several factors:a . Surf ace Ar ea

T he reaction rate is influenced by the surface area between reactants. A solid will reamore quickly if its surface is widened by changing its form bar to powder or making the sismaller.

T he reaction rate increase happens becauses m a ller siz es of th e s am e m a ss of s ol id h ave a gr ea ter surface a r ea compared to larger pieces of the solid. So the collision of the solidwhich have the small pieces is more than large pieces.

b . T emp er a tur e I ncrease of temperature will increase the reaction rate.T he increasing of temperature

causes the rate of molecule move increase so the kinetic energy of reactant moleculincrease, so its kinetic energy has higher point than its activation energy (Ea) or kinetenergy can reach activation energy (Ea).

c. C on centr a t ionI ncreasing the concentration of reactants will increase the frequency of collision amon

the reactants particles.T his is because in a concentrated solution, the distance among particlesis relatively close, so they are easy to collide.

d . P r ess ur e For reaction is using reactants on gas state.T he reaction rate of this reaction is influence

by pressure. Remember the ideal gas equation . Inc reasi ng p ressure will bedecrease volume and increase concent ra t ion. So, the reaction rate of this reaction will beincrease.

e. C a ta lys t


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Added catalyst at reaction will be decrease activation energy so the reaction rate will faster.

4. Given:aA + bBp cC + dD

By experimentally, given the equation of reaction rate:v = k [A] p . [B]q

a. determine order of reaction b. determine order of reaction respect to Ac. determine order of reaction respect to Bd. determine order of reaction respect to Ce. determine order of reaction respect to Df. I s a equal with p; b equal with q? Does possible order of reaction equal with coefficient ofreactant?

Answer:a. order of reaction = p+q b. order of reaction respect to A=pc. order of reaction respect to B=qd. order of reaction respect to C= not knowne. order of reaction respect to D=not knownf. no, maybe but order of reaction is not determined by reactant coefficient.

5.a. Mention the factors that not influenced with k (reaction rate constant)

b. Determine the unit of k Answer a. concentration, pressure, catalyst and surface are b. Unit of k is depend on the order of reaction, the k unit of zero order reaction is differentwith k unit of first order reaction and soon.

6. Given reaction between salt is pA3B + q C2D p r AxDy + s CaB bFrom the observation on the reaction rate data obtained as follows:* I f the concentration of A3B increased 2 times the concentration of C2D is constant, thereaction rate will be 8 times.* I f the concentration of A3B and C2D increased 2 times, the reaction rate becomes 32 times.a. Determine the reaction order b. Determine the units of k c. determine the value of p, q, r and s Answer:

a. Reaction order A3B


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C2D

reaction order respect to A3B=3reaction order respect to C2D=2reaction order=3+2=5

b .

c . P , q, r, s can not determine with reaction order 7. From the reaction : 2H2(g) + 2NO(g) p 2H2O(g) + N2(g) given the experiment data as follow:

Number of experiment

Initial concentration (Molar) Reaction rate(molar/second)H2 NO

1 2,00 . 10-3 8,00. 10-3 1,13. 10-4 2 4,00. 10-3 8,00. 10-3 2,26. 10-4

3 8,00. 10-3

2,00. 10-3

2,83. 10-3

4 8,00. 10-3 6,00. 10-3 2,54. 10-2 a. determine the reaction order b. determine the value of k

Answer:I f the reaction order of H2 = m and the reaction order of NO = n


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T he reaction order of H2 is determined based on the concentration of NO which is constant,that is in experiment number 1 and 2

= m=1T he reaction order of NO is determined based on the concentration of H2 which is constant,that is in experiment number 3 and 4

= n=2a. T he reaction order respect to H2 is 1

T he reaction order respect to NO is 2T he total reaction order is 3

b. T he value of k v1=k [H2] [NO]2

8. Given the reaction: 2A(g) + B(g) p A2B(g) given the experiment data as follow: Number of

experiment

Initial concentration (molar) time

(second)A B1 M M t2 2M 2M 1/8 t3 2M M t

a. determine the reaction order b. what is time that needed, if the concentration of each reactant is 3M?

Answer:a. I f the reaction order of A = m and the reaction order of B = n

T he reaction order of A is determined based on the concentration of B which is constan

that is in experiment number 1 and 3=

Because and [B]1=[B]2 so,

= =

= m=2


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T he reaction order of B is determined based on the concentration of A which is constanthat is in experiment number 2 and 3

= Because [A] 2=[A] 3 so,

= =

= n=1T he reaction order on A is 2T he reaction order on B is 1T he total reaction order is 3

T he value of k v=k[A]2[B]

b.when [A] and [B]=3 Mv=k[A]2[B]

9. From the reaction A + Bp C, given the equation of reaction rate is: v = k [A]2 c. How many times reaction rate will be increase, if the concentration of A is increased 2 times an

the concentration of B is increased 10 times?d. How many times reaction rate will be increase, if the concentration of B is increased 10 times

and the concentration of B is constant?Answer:K nown:the equation of reaction rate is: v = k [A]2 a. v1 = k [A]2

v2 = k [2A]2 v2 = k 4A2 v 2= 4 v1

b. v is constant because B is not influence in that reaction

10. Given the coefficient of reaction temperature = 2.If the reaction rate of reaction in 500C is 0,005M/det, what is reaction rate in 800C and 950C ?


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Answer:At 80o C

at 950C

11. Given the reaction diagram of Ap B as follow:

Description:T he up path curve isa curve point on the reaction energy without catalystT he down path curve isa curve point on the reaction energy with catalyst a. W hat is the activation energy without a catalyst? b. W hat is the activation energy with catalyst?

c. W hat is the enthalpy reaction?Answer:a. T he activation energy without a catalyst =200 J-98 J=102 J b. T he activation energy with catalyst=160 J-98 J=62 Jc. Enthalpy of reaction=35 J 200 J =-165 J

12. a. Does catalyst take part on reaction?

A

A*

B

A*

200 j

160 j

98 j

35 j

H

t


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b. W hy is catalyst (positive) increase the reaction rate?c. Does promotor equal with positive catalyst?d. Does inhibitor equal with negative catalyst?Answer:a. yes

b. catalyst (positive) allow reactions to occur via alternative pathways with the lower activation energy so the reaction rates is increasing.c. Nod. No

13. W hat is the different between catalyst and promotor?Answer: catalyst does take part in the reaction, but all of it is re-formed in later steps, but promotor not.

14. W hat is the different between negative catalyst and inhibitor?

Answer: negative catalyst does take part in the reaction, but all of it is re-formed in later ste but inhibitor not.

15. In mechanism reaction, which is called rate determining step?T he slowest step is called the rate-determining step

C h em ica l eq u i lib r ium

1. W hat is the physical condition must be filled by the system will undergoing on equilibrium

condition?Answer:At the forward reaction rate is equal with reverse reaction rate and also at the change of Gibbs free energy of reaction is zero (( Greaction= 0)

2. W hen the equilibrium condition is reached, the reactant is remaining, but also not changed, whereasthe product is not increased. Does the reaction stopped?Answer: No, Chemical equilibrium ared yn am ic eq u i li br ium; that is, individual molecules arecontinually reacting, even though the overall composition of the reaction mixture does no

change

3. How is reaction rate when equilibrium reached?At equilibrium the forward reaction rate is equal with reverse reaction rate

4. For homogeneous reaction among gas: pA + qBqC + s DW hat is definition of equilibrium constantK c andK p? W hat is the relationship betweenK p andK c?


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Answer:T he equilibrium constant K c, is defined as the product of theequilibrium concent ra t ion s (moles per liter) of the products, each raised to the power that corresponds to its coefficient inthe balanced equation, divided by the product of theequilibrium concent ra t ion s of reactants,each raised to the power that corresponds to its coefficient in the balanced equation.

? A ? A? A ? Aq p

sr

B A

DC K c !

T he relationshipK p andK c:

n= difference the total of power of nominator and the total of power of denominator

5. How is reactant concentration versus time curve at the equilibrium reaction?Answer:Reaction: Consider a case in which the coefficients in the equation for a reaction are all 1.W hensubstances A and B react, the rate of the forward reaction decreases as time passes becauthe concentration of A and B decrease.

6. How is the reaction rate versus time curve at the equilibrium reaction?Reaction: As more C and D molecules are formed, more can react, and so the rate of reaction between C and increases with time. Eventually, the two reactions occur at the same rate, and the system is aequilibrium

[C] and [D]

[A] and [B]

Equilibriu

time

concentratio

[C] and [D]

[A] and [B]

Equilibriu time

concentratio


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7. W hat is definition of equilibrium dissociation?W hat is that opposite?W hat is dissociationdegree?Answer:Equilibrium dissociation is equilibrium condition that happened dissociation in the closystemT he opposite of Equilibrium dissociation is Equilibrium formation,Dissociation degree is ratio between the number of substance that dissociated and the numbof initiall substance.

9.W hat are factors that influence the equilibrium and how is that effect?T he factors that influence the equilibrium and how is that effectT hree types of changes can disturb the equilibrium of a reaction.1. Changes in concentration

y I f the concentration of substance increase, the reaction will shift to the opposite part oequation of equation of the substance which increase

y I f the concentration of substance decrease, the reaction will shift to direction of the part of equation of the substance which decrease

2. Changes in pressure or volume (for reactions that involve gases)y I f the pressure is increased (volume is reduced), the equilibrium will shift toward the

amount of gas which is smaller.y I f the pressure is reduced (volume is increased), the equilibrium will shift toward the

amount of moles which is larger y T he amount of moles in an equilibrium reaction is shown by the number reaction

coefficient.y I f the amount of moles of substance on the right is equal to that on the left, the chang

in pressure-volume does not shift the equilibrium.

3 . Changes in temperature R aisi ng th e t em pera t ure of an equilibrium mixture shifts the equilibrium condition in thedirection of the endothermic reaction. Loweri ng th e t em pera t ure causes a shift in thedirection of the exothermic reaction

10. Explain, why?a. Equilibrium shifts to rightward if reactant is increased? b. Equilibrium shifts to the position that larger total of mol, if the volume of container is increased?


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c. Dissociation equilibrium of HI does not shift if the volume of container is increased?d. Equilibrium shifts to endothermic position if reactant is increased?

Answer:a. W hen more of any reactant isadded to the system, the value of Q ( R ea ct ion Q uot ient)

changes, so it no longer matches K c. Q < K c, and the forward reaction occurs more rapidlyand to a greater extent than the reverse reaction until equilibrium is reestablished

b. If in an equilibrium reaction of gas, the pressure is increased, according Le-Chatelier principle, thesystem will try to reduce the effect of the increasing pressure by method of reducing the number omolecules or the amount of mole substances.Such changes therefore affect the value of Q for reactions in which the number of moles of gaseous reactants differs from the number of moles of gaseous products. For an ideal gas

T he term (n/V ) represents concentration, that is, mol/L. At constant temperature,n, R andT are constants.T hus, if the volume of gas decreases, its partial pressure increases and its

concentration (n/V ) increase.I f the volume of a gas increases, both its partial pressure andits concentration decrease.

c. Given reaction: T he amount of moles of substance on the right is equal to that on the left; the change in pressure-volume does not shift the equilibrium

d. Heatis produced by the forward (exothermic) reaction. Suppose we increase thetemperature at constant pressure by adding heat to the system.T his favors the reaction tothe left, removing some of the extra heat. Lowering the temperature favors the reaction to

the right as the system replaces some of the heat that was removed

11. W hat are factors that influence the value of equilibrium constant?Answer:T he factor that influenced the value of equilibrium constant is temperature.

12. W rite dissociation reaction from:1. P otassium carbonate 2. Ammonia 3.salmiak 4.P Cl5 5.SO3 6. HCl 7. Vapor of HBr 8. . N2O4 9. BariumP eroxide

Answer:1. P otassium carbonateCaCO3(s) CaO (s) + CO2(g)

2. Ammonia2NH3 N2 (g)+3 H2(g)

3. NH4Cl (salmiak) NH4Cl(s) NH3 (g)+ HCl(g)

4. P Cl5


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P Cl5(g) P Cl3(g) + Cl2(g)5. SO3

2SO3 (g) 2SO2 (g) + O2(g)6. HCl

2HCl(g) H2(g) + Cl2(g)

7. HBr 2 HBr(g) H2(g) +Br 2(g)8. N2O4

N2O4(g) 2NO2(g)

13. DetermineK c andK p on dissociation reaction of no.10 above.1. P otassium carbonate

CaCO3(s) CaO (s) + CO2(g)

2. Ammonia

2NH3(g) N2 (g)+3 H2(g)

3. NH4Cl (salmiak) NH4Cl(s) NH3 (g)+ HCl(g)

4. P Cl5 P Cl5(g) P Cl3(g) + Cl2(g)

5. SO3 2SO3 (g) 2SO2 (g) + O2(g)

6. HCl2HCl(g) H2(g) + Cl2(g)


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c. what the room pressure before dissociation and what is pressure after dissociation if the roomvolume is constant

d. W hat is the total number of mole in equilibrium?e. In the constant temperature, done compress room to be 5 liter.W hat is the number of mol of each

gas on the room now.

f. T he volume is constant (5 L), but that room is injected with 3 mol hydrogen gas at constanttemperature.W hat is the number of mol HI after equilibrium again?

2 HI (aq) H2 (g) + I 2(g)I nitial 4 mol - -Reaction 1.5 mol ~ 0.75 mol ~ 0.75 molEquilibrium 2.5 mol 0.75 mol 0.75 mol

Answer:a. b.

[H2] in equilibrium = 0.75 mol/10 L =0.075 M[I 2] in equilibrium = 0.75 mol/10 L =0.075 M[HI] in equilibrium = 2.5 mol/10 L =0.25 M

c. P ressure before dissociation

Pressure after dissociation = 13.2 atmd. T otal number in equilibrium=2.5 mol+0.75 mol+ 0.75 mol= 4 mol

e. If the volume is compressed until 5 L at constant temperatureK c is constant=0.09, x is mol H2 and I 2 in equilibrium so mol of HI in equilibrium is (4-2x)


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T hus, the number mol of HI in equilibrium=(4-2x0.75)=2.5 molT he change of volume does not influence the equilibrium because the difference of totalmol reactant and product is 0.

f. Mol H2 andI 2 is 0.75 mol2 HI (aq) H2 (g) + I 2(g)

I nitial 2.5 mol 0.75 mol+3=3.75 mol 0.75 molReaction 2x ~ X ~ xEquilibrium 2.5-2x mol 3.75-x mol 0.75-x mol

15. In 10-L of the close room at 1270C is found 4 mol HI (g) that dissociated 0.6.a. W hat is the number of molI 2 in the room after equilibrium? b. W hat is the value of K c andK p?c. At the constant volume, the temperature will be increase to be 2000C. On this new temperature,

the value of K c will be increase 1.5 times of K c at 1270C.1. W hat is the value of dissociation degree at 2000C?2. W hat is the number of mol HI in the new equilibrium?

Answer:2 HI (aq) H2 (g) + I 2(g)

I nitial 4 mol - -Reaction 0.6 x 4=2.4mol 1.2 mol 1.2 molEquilibrium 1,6 mol 1.2 mol 1.2 mol

a. T he number volume of molI 2 in the room after equilibrium=1.2 mol b.

[H2] in equilibrium = 1.2 mol/10 L =0.12 M[I 2] in equilibrium = 1.2 mol/10 L =0.12 M

[HI

] in equilibrium = 1.6 mol/10 L =0.16 M c. K c at 200C=1.5 timesK c at 127C


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0.918x4 (2x.0.918)=xx=3.672-1.836x2.836 x=3.672x=1.29

T hus, mol HI=4-2.(1.29)Mol HI=1.42 (at equilibrium)

16. On the 1-L container is found 1 mol SO3 that dissociated on certain temperature. After equilibrium isreached, mol fraction of O2 on the container is 1/5. Calculate the dissociation degree andK p, if thereaction temperature is 600K .

Answer:2 SO 3 (g) 2 SO 2 (g) + O 2

In i t ia l 1 molC h ang e d u e to r eac t ion 2x mol ~ 2 x mol ~ x mol

Eq u i lib r ium 1-2x mol 2 x mol x mol

Mol fraction of O2=1/5

1(1+x)=5x1+x=5x1=5x-xx=1/4Mol SO3=1-2x=1-(2x0.25)=0.5 molMol SO2=2x0.25=0.5 molMol O2=0.25 mol


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17. Given the dissociation of salmiak on equilibrium condition.W hat is total mol of salmiak (will be

increased/will be decreased:a. on the container is injected with ammonia

b. volume of container is increasedc. pressure of container is increasedd. temperature of container is increased

Answer: NH4Cl(s) NH3 (g)+ HCl(g)

a. I f the space is added into the total number of moles of ammonia will be many moresalmiak. b. I f the volume of space is enlarged, then the number of moles salmiak will be reduced.c. I f the enlarged chamber pressure, the number of mole salmiak will increase.

d. I f the room temperature is raised, then the number of moles salmiak will increase. 18. On the production of sulfuric acid industry, one of that step is : 2SO2 + O2 2SO3 + q jouleFor produce the maximum product based on Gulberg andW aage Law:a. the volume of container must be (increased/decreased) b. the pressure of container must be (increased/decreased) c. the temperature of reaction (high / low)Answer:a. decreased b. increasedc. low

19. W hy on the dissociation of HCl, equilibrium not shift when the volume of container/pressurare changed?Answer:2HCl H2 + Cl2 the amount of moles of substance on the right is equal to that on the left, the change in pressure-volume does not shift the equilibrium

20. Given the dissociation reaction: 2A3B + C, H = -300 joule. On that reaction do the expansion of volume.T he consequence that happened is:a. dissociation degree will be (larger/smaller) b. concentration of A (increase/decrease)c. equilibrium constant will be (larger/smaller)Answer:a. Constant b. Decreasec. Constant


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TUG AS MANDIRII NDI VI DUALT ASK

L aj u R eak si Reaction RateI . Give the cross on the most correct answer


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. Generally, the chemical reaction undergoing step by step. A series of reaction step is called. . . . . . . . . .

A. reaction level D. reaction rateB. reaction order E. reaction mechanismC. reaction series

Answer: E

2. All the steps listed below affect the reaction rate,exce pt . . . . . . . .A. addition of one reagent substancesB. the addition product of reactionC. given catalystD. changes in reaction temperatureE. reactant particle size is reduced

Answer: B

3. Sodium reacts with water great at room temperature, while the iron is not.T his shows thatthe reaction rate depends on. . . . . . . .A. temperature D. reactant stateB. type of reagent E. catalystC. the surface area

Answer: B

4. T he increase in temperature will accelerate the reaction rate, because the increasetemperature will. . . . . . ..A. raise the activation energy of the reacting substancesB. increasing concentrations of substances which reactC. increase the kinetic energy of reactant moleculesD. increasing pressureE. enlarge the surface areaAnswer: C

5. Among the expected pairing reagent following having the greatest rate is. . . . . . . . .A. 50 grams of Al powder with 0.01 M HCl solutionB. 50 grams of Al powder with 0.001 M HCl solutionC. 50 grams of Al powder with 0.1 M HCl solutionD. 50 grams of Al plates with 0.01 M HCl solutionE. 50 grams of Al plates with 0.1 M HCl solutionAnswer: C


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6. Every increase of 200C, the reaction rate becomes 3 times faster that before, if at 200Creaction rate undergoing 9 minutes, thus the reaction rate at 800C is . . . .

A. 6,67 dt D. 30 dtB. 10 dt E. 40 dtC. 20 dt

Answer: C

7. T he reaction A + B p C + D is obtain the following data:

[A] [B] v ( M / dt)0,1 0,1 30,1 0,5 150,3 0,1 27

T hese reactions have a reaction rate equation. . . . . . . . . . .A. v = k [A] [B] D. ][[A].k 1/2 Bv ! B. v = k . [A] [B]2 E. v = k . [A]2 [B]C. 2/1][[A].k Bv !

Answer: E

8. On the reaction A + B p C is obtain the data:

NoI nitial concentration

Reaction rate (M / dt)[A] M [B] M

1 2 x 10 3

4 x 10-3

6 x 10-7

2 2 x 10 3 8 x 10-3 12 x 10-7 3 4 x 10 3 4 x 10-3 24 x 10-7

Reaction order is..A. 1 D. 4B. 2 E. 5C. 3

Answer: C

9. T he existence of a positive catalyst in a reaction can accelerate reaction rate, because. . .A. increase the number of collisions D. lowering the activation energyB. reduce the number of collisions E. does not change the reaction rateC. adding activation energyAnswer: D

10. I f on the reaction A + B p C + D


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T he concentration of A increase 2 times, the reaction rate will be 8 times faster that befoT hus, the reaction order respect to A is

A. 4 D. 1B. 3 E. 0C. 2Answer: B

II . Fill the point on below1. I f the equation reaction rate of:

2H2 (g) + 2 NO (g) p 2 H2O (g) + N2 (g) is v = k . [H2] . [NO]2 thus : - order reaction respect to H2 = 1

- tingkat reaksi terhadap NO = 2- tingkat reaksi keseluruhan = 3

Because the order of reaction is 3, thus the reaction above is called with third reactioorder

2. Given the reaction rate:A p Bis a molar / second at 200C

if the temperature coefficient of reaction is 2, calculate the reaction rate at 600Cthe temperature of reaction from 200C to 600Ctemperature rise = 400C or = 4 x 100C because every raise 100C the reaction rate to be 2 times, thus raising 400C the reaction rate

to be 2 x 2 x 2 x 2 times than before = 16 timesif the initial reaction rate = a mol / liter .dt, thus reaction rate at 600C= 16 .x a mol / liter . dt

III . Answer the questions below correctly1. Mention the definition of reaction rate!

Answer:Definition of Reaction Rate is the measure representing the decrease of reactants amou per unit of time or the increase of products amount per unit of time

2. W hy with the same mass of iron powder would be easier to corrosive than the rusty iron plates?Answer:T his condition can be explained with the one of factors that influence the reaction ratthis is surface area.T he reaction rate increase happens becauses m aller p iece s of th e s a m e m a ss of s ol id have a gr ea ter s urf ace a r ea compared to larger pieces of the solid.So the collision of the solid which have the small pieces is more than large pieces.I n iron


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powder has larger surface areas and hence more atoms exposed to the oxygen of the acorrosive easily

3. Reaction:2NO (g) + Cl2 (g) p 2NOCl (g)

T he equation reaction rate v = k . [NO]2. [Cl2]a) Decide the reaction order of each reagent b) the total reaction order c) if each concentration of NO and Cl2 increased 2 times, how change the reaction rate?Answer:(a) Reaction order respect to NO is 2 and reaction order respect to Cl2 is 1(b) T otal reaction order=3(c) T he change of reaction rate is increase 8 times than before

4. Mention of factors that influence reaction rateAnswer: Concentration, surface area, pressure temperature, catalyst

5. Mention the kinds of catalystAnswer: positive catalyst and negative catalyst, homogeneous catalyst and heterogeneocatalyst

6. I n a 10 liter vessel, initially, there are 12 moles of pure HCl gas. After 3 hours in this rooformed was 3 mol of H2. Determine the rate of dissociation of HCl.Answer:

7. Based on collision theory, why:

a. concentration of reactant influence the reaction rate? b. temperature of reaction influence the reaction rate ?c. size/surface area influence the reaction rate ?d. catalyst influence the reaction rate?Answer:

a. concentration of reactant influence the reaction rateIncreased concentrations of reacting species result in greater numbers of collisions per unittime.T his is because in a concentrated solution, the distance among particles is relativelyclose, so they are easy to collide. So, the reaction rate is more quickly.

b. temperature of reaction influence the reaction rateIncreasing temperature, caused particle having kinetic energy which is larger than activationenergy.T his condition enables the occurrence of more effective collisions between particles,so the reaction proceeds more quickly.


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c. size/surface area influence the reaction rateIn the reaction of solids which are powdery in form (large surface area), every part of thesolids will react immediately with other substance simultaneously because the contactingsurface area of the solids is relatively large, thus that particles of solid is easy to collide, so threaction rate is more quickly. Mean while, in the reaction of solids in the form of rod or plate,

the reaction will occur at the surface of solids which contacts with other substances, so thereaction for all parts of the solids to occur takes along time.d. catalyst influence the reaction rate

T he presence of a catalyst can increase the fraction of colliding molecules that have the propeorientations.

8. W hat is the definition of activation energy?Answer T he activation energy, E a, is the kinetic energy that reactant molecules must have to allow them toreach the transition state.

K es et im ba ng an K i m ia C hem ica l E q u ilib r ium

1. Consider the following equilibrium:2HI H2 + I 2 I f initially there are 4 M HI and after the dissociation are 1.5 M H2 in equilibrium,a. How many M of HI is dissociated? W hat is the value of E ? b. How many MI 2 that is formed?


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c. Draw a graph of changes in the concentration of HI , H2 and I 2 of the time at equilibrium.Answer:

2 HI (aq) H2 (g) + I 2(g)I nitial 4 M - -Reaction 2.5 M ~ 1.25 M ~ 1.25MEquilibrium 1.5 M 1.25 M 1.25M

D 4-1.5 M=2.5 M, = , E =(2.5/4)=0.625E I 2 that formed is 1.25 MF

2. Given the reaction A B . Initially, the reaction rate Ap B is 10 M/det. After equilibrium, thereaction rate will be 6 M/deta. make the reaction rate curve of Ap B versus time b. make the reaction rate curve of Bp A versus timec. make the reaction rate curve of AB versus timeAnswer:a.

b.

H2

I 2

HI

t im e

c o n c e n

t r a

t i o n

4

2.5

1.25

v

t

10

v

v

t

10

v

10


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c.

3. Given the value of K c for reaction 2HI H2 + I 2 is K 1, while for HI H2 + I 2 is K 2, what isrelationship betweenK 1 andK 2 ?Answer:

4. If the value of K c at certain temperature for reaction 2HClH2 + Cl2 is 1.

a. investigate, what at that temperature, 10 mol H2, 5 mol Cl2 and 10 mol HI on the equilibrium state? b. if on the room is found 25 mol HI on the equilibrium state, what is the number of mol H2 and I 2 on

this room ?Answer:a. 10 mol H2, 5 mol Cl2 and 10 mol HI

K now:2 HCl (aq) H2 (g) + Cl2(g)

I nitialReactionEquilibrium 10 mol 5 mol 10 mol

equilibiu

not

x

x xQc ,5.01005010

105

2 !!

-

-

-

!

b. 25 mol H2,K now:

2 HI (aq) H2 (g) + I 2(g)I nitial


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ReactionEquilibrium 25 mol

? A? A? A2

22

H I

H I K c !

5. Given the homogeneous reaction CO + H2O CO2 + H2.Initially, there 0,1 M each of CO and H2O. At4000C the equilibrium constant isK c = 9. How many M CO which reacts?Answer:

K now:K c = 9CO (g) + H2O CO2 (g) + H2(g)

I nitial 0.1 M 0.1 M - -Reaction x M ~ X ~ x ~ xEquilibrium 0.1-x M 0.1-x x xAsk: M CO which react=.?

Solution: ? A? A? A? AO C O

C O K c

2

22!

)1.0)(1.0(.9

x x x x

!

)1.0(.3

x x!

x=3/7 6. T he value of K c at certain temperature for reaction NH3 N2 + 1 H2 is 5,2 . 10-5. W hat is the

value of K

c at that temperature for reaction N2 + 3H2 2NH3 ?Answer:

7. Given, at certain temperature:

N2 + O2 2 NO K c1= 4,1 . 10 31 N2 + O2 N2O K c2 = 2,4 . 10 18 At that temperature, what is the value of K c for reaction N2O + O2 2 NO ?Answer:K c for reaction N2O + O2 2 NO N2O N2 + O2 (1/K c2) =(1/ 2,4 . 10 18) N2 + O2 2 NO K c1= 4,1 . 10 31 N2O + O2 2 NO K c=(1/K c2)*K c1=1.708 x 10-13

8. T he value of K p for reaction A B + C is 0.328.W hat is the value of K c?


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T he reaction is not known the phase of reactant and product, and temperatureIf all of phase of reactant and product is gas phase

9. Given the heterogeneous equilibrium reaction C(s)

+ CO2(g) 2CO. DefineK p andK c!Answer:

10. From the equilibrium reaction CaCO3(s) CaO(s) + CO2 , known that at certain temperature, the valueof K p = 3.W hat is the value of K c ?Answer:

11. W hich reaction which moved on rightward, if the pressure of room is increased?(1) H2 + I 2 2HI (2) N2 + 3H2 2NH3 (3) N2O4 2NO2 (4) 2H2 + O2 2H2O

Answer: increasing temperature, the equilibrium will be shift to the greater number of mol or coefficient. So the answer are (2), (4)

12. Given the reaction 2NO N2 + O2 H = +43,2 kkalW hat manner can be done so the dissociation degree will increase?Reduced temperature, [NO] is enlarged

13. Given the reaction: H2O(l) H2(g) + O2(g) W hat manner can be done so the reaction move on therightward?Answer:Increasing volume and decreasing pressure.

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