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8/10/2019 Pembahasan Ptk 2011 ptk ptk ptk

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2/18

1. A sample of calcium nitrate, Ca(NO3)2, with a

formula weight of 164 g/mol, has 5.00 x 1025atoms

of oxygen. How many kilograms of Ca(NO3)2are

present?

Answer :


3/18

2. Dilute sulfuric acid has to be added to dry

charged batteries at service stations to activate a

battery. You are asked to prepare a batch of new

18.63% acid as follows. A tank of old weak battery

acid (H2SO4) solution contains 12.43% H2SO4(theremainder is pure water). If 200 kg of 77.7%

H2SO4is added to the tank, and the final solution

is to be 18.63% H2SO4. How many kilograms of

battery acid have been made?


4/18

Basis : 200 kg T

MIXINGW = ... kg

WH,W= 0.1243

Wa,W= 0.8757

T = 200 kg

WH,T= 0.777Wa,T

= 0.223

N = ... kg

WH,N=

0.1863

Wa,N = 0.8137

W : weak battery

N : new battery

T : addition

H : H2SO4

a : water

W + T = N

W + 200 = N

W = N - 200

Overall massbalance :

H2SO4mass balance :

WH,W. W + WH,T.T = WH,N.N

0.1243 W + 0.777 (200) = 0.1863 N

0.1243 (N-200) + 155.4 = 0.1863 N0.1243 N24.86 + 155.4 = 0.1863 N

130.54 = 0.062 N

N = 2105 kg

So, 2105 ki log rams of battery acid have been made


5/18

3. Fish caught by human beings can be turned into

fish meal, and the fish meal can be used as feed toproduce meat for human beings or used directly asfood. The direct use of fish meal significantlyincreases the efficiency of the food chain. However,

fish-protein concentrate, primarily for aestheticreasons, is used mainly as a supplementary proteinfood. As such, it competes with soy and other oilseedproteins.

In the processing of the fish, after the oil is extracted,

the fish cake is dried in rotary drum dryers, finelyground, and packed. In a given batch of fish cake thatcontains 80% water (the remainder is dry cake), 100kg of water is removed, and it is found that the fish

cake is then 40% water. The weight of the fish cakeori inall ut into the dr er is ...


6/18

Basis : 100 kg water removed

DRYINGF = ... kg

Wa,F= 0.80

Wd,F= 0.20

W = 100 kg

Wa,w= 1.00

R= ... kg

Wa,F= 0.40

Wd,F= 0.60

F : feed

R : result

W : water removed

a : water component

d : Dry cakecomponent

F = R + W

F = R + 100

R = F - 100


Water mass Balance :

Wa,F. F = Wa,W.W + Wa,R.R

0.80 F = 1.00 (100) + 0.40 R

0.80 F = 100 + 0.40 (F-100)0.80 F = 100 + 0.40 F -40

0.40 F = 60

F = 150

So, the weight of th e f ish cake or iginal ly put into the dryer is 150 kg


7/18

Chemical Engineers shall uphold and advance the

integr i ty, honorand digni tyof the engineering

profession by:

5. Being honest and impartial and serving with fidelity

their employers, their clients, and the public (, ., .)

Answer: d, f, j, k


8/18

Chemical Engineers shall uphold and advance the

integr i ty, honorand digni tyof the engineering

profession by:

6. Striving to increase the competence and prestige of

the engineering profession (., ., .)

Answer: c, e, i, h


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11/18

9. Catalytic reforming is a process to convert straight hydrocarbonto

cyclic formby producing hydrogen.10. Alkylationunit produces high octane component for gasoline

blending.

11. Fluidized catalytic cracker unit upgrades heavier fractioninto

shorter hydrocarbon that is a more valuable products.12. Hydrocracker unit uses hydrogento upgrade heavier fractions into

shorter hydrocarbon/gasoline chains.

13. Gas synthesis is a mixture of carbon monoxideand hydrogen.

14. Fischer-Tropsch synthesis is a set of chemical reactions that convert

synthesis gas into gaseous and or liquidhydrocarbons.


12/18

15.Reynolds number or Re is a dimensionlessnumberassociated with the smoothness of flow of a fluid that

used in fluid mechanics.

16.Re shows the ratio between velocity, fluid density,

fluid viscosity, and characteristic length/diameter.

17.So that the formulation of Re is

18.This flow scheme shows a turbulentflow with the Re

more than4000.

This flow scheme shows a laminarflow with the Re less

than2100.

vdRe


13/18

18.A feed is flowing to a separator in a rate of 100kg/hr.

this feed contains 40% benzene, 50% toluene, and therest are acetone. Separator separate this feed to the top

column (flow rate 40kg/hr) and bottom column

(60kg/hr).

The top column contains 80% benzene while the bottomcolumn contains 80% toluene. Define the composition

of flowing through the top and bottom column!

S

e

pa

r

a

t

o

r

Feed (F1) =

100kg/hr

B = 0.4

T = 0.5

A = 0.1

Top (F2) = 40kg/hr

B = 0.8

T = ?

A = ?

Bottom (F3) =

40kg/hr

B = ?

T = 0.8

A = ?


14/18

Neraca Massa Total

Feed (F1)= Top (F2) + Bottom (F3)

Neraca Massa Benzene

XB1. F1 = XB2. F2+ XB3. F3(0.4) (100)kg/hr = (0.8)(40)kg/hr + XB3(60)kg/hr

XB3 = 0.133kg/hr

Neraca Massa Toluene

XT1. F1 = XT2. F2+ XT3. F3(0.5) (100)kg/hr = XT2 . (40)kg/hr + (0.8)(60)kg/hr

XT2 = 0.05kg/hr

Top : XB2+ XT2+ XA2= 1

XA2= 1- (0.8 + 0.05) = 0.15

Bottom : XB3+ XT3+ XA3= 1

XA3= 1- (0.8 + 0.133) = 0.067


15/18

2. A manufacturer of briquets has a contract to

make briquets for barbecuing that are guaranteedto not contain over 10% moisture. The basic

material they use has the analysis : moisture

12.4%, volatile material 16.6%, carbon 57.5%, and

ash 13.5%. To meet the specifications they plan to

mix with the base material a certain amount of

petroleum coke that has the analysis : volatile

material 8.2%, carbon 88.7%, and moisture 3.1%.How much petroleum coke must be added per 100

lb of the base material


16/18

Basis : 100 lb FF : basic material

P : petroleum coke

B : briquet

v : volatile

m : moisturec : carbon

a : ashMIXER

F = 100 lb

Wm,F= 0.124

Wv,F= 0.166

Wc,F= 0.575

Wa,F= 0.135 P = ... lb

Wm,P= 0.031Wv,P= 0.082

Wc,P= 0.887

B = ... lb

Wm,B= 0.10

Wv,B=

Wc,B=

Wa,B=

Moistrue mass balance :

Wm,F. F + Wm,P.P = Wm,B.B

0.124 (100) + 0.031 (P) = 0.10 (B)12.4 + 0.031 (P) = 0.10(100+P)

12.4 + 0.031 (P) = 10 + 0.10 P

0.069 (P) = 2.4

P = 34.78

F + P = B

100 + P = B

B = 100 + P


So, the petor leum coke that is n eeded per 100 lb basic mater ia l is :


17/18

3. This is a definition of Sustainable

Development (SD)

SD is a development that meets the

needs of the present without

compromising the ability of future

generations to meet their own needs.

Write down three components of SD !


18/18 PEUI 2008

Economic:what things cost - and

how to make a business out of

providing infrastructure, goods or

services

Environmental:what impact those

things have on nature and the earths

support systems - which are finite

Social:how those things serve theneeds and quality of life of people and

their communities

Sustainable developmentaims to balance three elements

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