SOLUCIONES Guía de Ejercicios pH

8/2/2019 SOLUCIONES Gua de Ejercicios pH

1/7

Universidad Tecnolgica Metropolitana

Qumica Industrial

Qumica General II

1

SOLUCIONES Gua de Ejercicios de pH

1. Cul es el pH de 250 mL de:a) KOH 0.45 M

pOH = log OH pH = 14 pOH

pOH = log 0.45 pH = 14 0.34

pOH = 0.34 pH = 13.66

b) Ca(OH)2 0.078 M

+2

20.078 M 2 0.078 M0.078 M

0.156 M

Ca(OH) Ca 2 OH


pOH = log 0.156 pH = 14 0.80

pOH = 0.80 pH = 13.20

c) HClO4 0.068 M

+pH = log H

pH = log 0.068

pH = 1.16

d) HNO3 0.045 M

+pH = log H

pH = log 0.045

pH = 1.34

2. Cul es el pH de 300 mL de:a) CH3COOH 0.066 M

5

aK 1.75 10

3 3

3

e e a

3

CH COOH CH COO H

0 0 0

0.066 M

CH COO HK K K

CH COOH

Si

Sf x x x

25

6 2

6

3

1.75 10 0.066

1.155 10

1.155 10

1.07 10 M

x

x

x

x

x

+

3

pH = log H

pH = log 1.07 10

pH = 2.97


2/7

Universidad Tecnolgica Metropolitana Dallits Sagredo Oyarce

Qumica Industrial

Qumica General II

2

b) HNO2 0.68 M4

aK 4.5 10

2 2

2

e e a

2

HNO H NO

0 0 0

0.68 M

H NOK K K

HNO

Si

Sf x x x

24

4 2

4

4.5 100.68

3.06 10

3.06 10

0.017 M

x

x

x

x

x

+pH = log H

pH = log 0.017

pH = 1.76

c) NH3 0.024 M5

bK 1.8 10

4 4

4

e e b

4

NH OH NH OH

0 0 0

0.024 M

NH OHK K K

NH OH

Si

Sf x x x

25

7 2

7

4

1.8 100.024

4.32 10

4.32 10

6.57 10 M

x

x

x

x

x

4


pOH = log 6.57 10 pH = 14 3.18

pOH = 3.18 pH = 10.82


3/7


Qumica Industrial

Qumica General II

3

3. Cul es el pH de 100 mL de solucin que tiene disuelto:a) 0.7 mL de HCl gm m mL32 % 1,19

33

1.19 gc 32 gp0.83 gc 0.26 gp

1 mL 0.7 mL 100 gc 0.83gc

1 mol 7.12 10 moles7.12 10 moles 0.0172 M

36.5 g 0.26 gp 100 mL 1000 mL

x x

x x

+pH = log H

pH = log 0.0172

pH = 1.76

b) 0.4 g de NaOH, de un m m90 %

3

3

90 gp 1 mol0.36 gp 9 10 moles

100 gc 0.4 gc 40 g 0.36 gp

9 10 moles0.09 M pOH = log OH pH = 14 pOH

100 mL 1000 mL

pOH = log 0.09 pH = 14 1.04

pOH = 1.04 pH = 12.96

x x

x

c) 0.8 mL de NH3 5gm m mL b62 % 0.9 K 1.8 10

0.9 gc 62 gp0.72 gc 0.44 gp

1 mL 0.8 mL 100 gc 0.72gc

1 mol 0.025 moles0.025 moles 0.25 M

17 g 0.44 gp 100 mL 1000 mL

x x

x x


4/7


Qumica Industrial

Qumica General II

4

4 4

4

e e b

4

NH OH NH OH

0 0 0

0.25 M

NH OHK K K

NH OH

Si

Sf x x x

25

6 2

6

3

1.8 100.25

4.5 10

4.5 10

2.12 10 M

x

x

x

x

x

3


pOH = log 2.12 10 pH = 14 2.67

pOH = 2.67 pH = 11.33

d) 1.4 mL de CH3COOH 5gm m mL a90 % 1.09 K 1.75 10

1.09 gc 90 gp1.52 gc 1.36 gp

1 mL 1.4 mL 100 gc 1.52gc

1 mol 0.02 moles0.02 moles 0.2 M

60 g 1.36 gp 100 mL 1000 mL

x x

x x

3 3

3

e e a

3

CH COOH CH COO H

0 0 0

0.2 M

CH COO HK K K

CH COOH

Si

Sf x x x

2

5

6 2

6

3

1.75 100.2

3.5 10

3.5 10

1.87 10 M

xx

x

x

x

+

3

pH = log H

pH = log 1.87 10

pH = 2.72


5/7


Qumica Industrial

Qumica General II

5

4. Cul es la M de una solucin de:a) HCl de pH = 3.7 4H 1.99 10 M

b) HNO3 de pH = 2.5 3H 3.16 10 M

c) KOH de pH = 13.2

pOH = 14 pH

pOH = 14 13.2

pOH = 0.8

OH 0.15M

d) NaOH de pH = 12.8

pOH = 14 pH

pOH = 14 12.8

pOH = 1.2

OH 0.063M

e) NH3 de pH = 8.35

bK 1.8 10

6

pOH = 14 pH

pOH = 14 8.3

pOH = 5.7

OH 1.99 10 M

4 4

6 6

4

e e b

4

NH OH NH OH

1.99 10 M 1.99 10 M

NH OH

K K KNH OH

Sf x

2

6

5

12

45

7

4

1.99 101.8 10

3.96 10NH OH

1.8 10

NH OH 2.2 10 M

x

x


6/7


Qumica Industrial

Qumica General II

6

f) CH3COOH de pH = 4.95

aK 1.75 10

5H 1.25 10 M

3 3

5 5

3

e e a

3

CH COOH CH COO H

1.25 10 M 1.25 10 M

CH COO HK K K

CH COOH

Sf x

2

5

5

10

35

6

3

1.25 101.75 10

1.56 10CH COOH

1.75 10

CH COOH 8.91 10 M

x

x

5. Cul es la concentracin:a) v v% de 300 mL de solucin que tiene disuelto 2 mL de etanol

v v

2 mL EtOH

0.66 %300 mL soluc 100 mL soluc

x

b) m v% de 200 mL de agua que disuelve 0.4 g de NaNO3

3 mv

0.4 g NaNO0.19 %

200.4 mL soluc 100 mL soluc

x

c) m m% de 1200 g de solucin que tiene disuelto 30 g de CuSO4

4 m

v

30 g CuSO

2.5 %1200 g soluc 100 g soluc

x


7/7


Qumica Industrial

Qumica General II

7

6. Cul es el pH de una mezcla:a) 200 mL HCl 0.035 M + 300 mL de HCl 0.066 M

0.035 moles 0.007 moles HCl1000 mL 200 mL

x 0.066 moles 0.0198 moles HCl1000 mL 300 mL

x

0.007 moles HCl + 0.0198 moles HCl = 0.0268 moles HCl

200 mL solucin + 300 mL solucin = 500 mL solucin

+

0.0268 moles HCl0.053 M

500 mL 1000 mL

pH = log H

pH = log 0.053

pH = 1.27

x

b) 48 mL NaOH 0.1 M + 100 mL NaOH 0.5 M + 50 mL de agua

0.1 mol0.0048 moles NaOH

1000 mL 48 mL

x

0.5 moles0.05 moles NaOH

1000 mL 100 mL

x

2

0.0048 moles NaOH + 0.05 moles NaOH = 0.0548 moles NaOH

48 mL solucin + 100 mL solucin + 50 mL H O = 298 mL solucin

0.0548 moles NaOH0.18 M

298 mL 1000 mL


pOH = log 0.18 pH = 14 0.74

pOH = 0.74 pH = 13.26

x

Documents

SOLUCIONES Guía de Ejercicios pH