kunci jawaban termokimia fix.docx

No.
So
al

Kunci
Jawab
an

No
.
So
al

Kunci
Jawab
an

1

d

11

c

2

c

12

a

3

e

13

e

4

b

14

e

5

e

15

c

6

a

16

d

7

d

17

d

8

e

18

b

9

a

19

d

10

a

20

b

13.

Penyelesaian
C4H8(g) + 6O2(g)  4CO2(g) + 4H2O(l)

∆Hreaksi= ∑ ∆Hof produk − ∑ ∆Ho f reaktan
= 4(-394 kJ/mol) + 4(-296,5 kJ/mol) – (-94,9 kJ/mol)
= -2762 kJ/mol – (-94, 9) kJ/mol
= - 2667, 1 kJ/mol

V
V STP

n=

ΔH°C =
14.

=

1
2 mol

44,8 L
22,4 L/mol

= 2 mol

x (- 2667, 1 kJ/mol) = - 1333,55 kJ

Penyelesaian
mol =

gram CO2
Mr CO 2

ΔH =

0,05mol
1mol

=

2,2 gram
gram

44
mol

= 0,05 mol

x 802,252 kJ

= 40,1126 kJ
15.
16.

Penyelesaian
ΔH = (ƩEpemutusan ikatan) – (ƩEpenggabungan ikatan)
ΔHHCl = H2 + Cl2 – 2HCl
-184 kJ = + 434 kJ + 242 kJ – 2H – Cl
-184 kJ = + 676 kJ – 2H – Cl
2H – Cl = + 676 kJ + 184 kJ
2H – Cl = + 860 kJ
H – Cl = + 430 kJ

17.

Penyelesaian
Fe2O3(s)  2Fe(s) + 1
3Ca(s) + 1

1
2

1
2

O2(g)

ΔH°f = + 800 kJ/mol

O2(g)  3 CaO(s)

ΔH°f = - 1920 kJ/mol

3Ca(s) + Fe2O3(s)  3CaO(s) + 2Fe(s) ΔH°f = - 1120 kJ/mol
18.

Penyelesaian
H2S(g) + 2 O2(g)  H2(g) + SO42-(aq)
H2(g) + SO42-(aq)  H2(g) + S(g) + 2O2(g)
H2SO4(aq)  H2S(g) + 2 O2(g)
H2SO4(aq)  H2(g) + S(g) + 2O2(g)

19.

q reaksi
mol

=

−3,57 kJ
0,005mol

= − 714 kJ mol−1

Penyelesaiaan
5H2(g) + 2

1
2

O2(g)  5 H2O(g)

4C(s) + 4O2(g)  4CO2(g)
C4H10(g)  4C(s) + 5H2(g)

1
2

C4H10(g) + 6
21.

ΔH4 = - 99 kJ

Penyelesaian
q larutan = m x c x ∆T = ( 25 + 25 )g x 4,2 Jg−1 oC−1 x 17oC = 3570 J
q reaksi= − q larutan = − 3570 J = − 3,57 kJ
Mol HCl = mol NaOH = 25 ml x 0,2 M = 5 mmol = 0,005 mol
∆Hᵒn =

20.

ΔH1 = - 22 kJ
ΔH2 = - 47 kJ
ΔH3 = - 30 kJ

ΔH1 = - 1210 kJ
ΔH2 = - 1574 kJ
ΔH3 = + 124, 5 kJ

O2(g)  4CO2(g) + 5 H2O(g) ΔH = - 2659, 5 kJ

Penyelesaian
ΔH = (ƩEpemutusan ikatan) – (ƩEpenggabungan ikatan)
= (1692 + 801 + 464 + 348) kJ/mol – (2115 + 348 + 386 + 482) kJ/mol
= 3305 kJ/mol – 3331 kJ/mol = - 26 kJ/mol

Essay
1. Kunci Jawaban :
a. ΔH°f MgO(s) =

1
2

(-1203,4) = - 601,7 kJ/mol

b. S(s) + O2(g)  SO2(g)
SO2(g) +
S(s) +

1
O2(g)  SO3(g)
2

3
O2(g)  SO3(g)
2

2. Kunci jawaban
2 C(s) + 3 H2(g)  C2H6 (g)
2 C(s) + 3 H2(g)  C2H4(g) + H2(g)

ΔH°reaksi = - 296,8 kJ
ΔH°reaksi = -98,9 kJ
ΔH°f SO3(g) = -395,7 kJ

ΔH1 = 273 kJ
ΔH2 = 593 kJ

C2H4(g) + H2(g)  C2H6 (g)

ΔH3 = 320 kJ

Jika ditanyakan ΔH reaksi 2C2H6 (g)  4C(s) + 6H2 (g) , maka:
C2H6 (g)  2 C(s) + 3 H2(g)
ΔH1 = - 273 kJ
C2H4(g) + H2(g)  2 C(s) + 3 H2(g)
ΔH2 = - 593 kJ
C2H6 (g)  C2H4(g) + H2(g)
ΔH3 = - 320 kJ
2C2H6 (g)  4C(s) + 6H2 (g)

ΔH = - 1186 kJ