\'ve noticed that recently most of my chemistry questions that get answered have

Question

've noticed that recently most of my chemistry questions that get answered have also been incorrect. I cant help but feel like this is a discrepncy between either the methods used, or the values of the refreances when choosing Ka,Ksp,Kb, costants of the nature. In order to avoid this I will post 2 pictures. The fisrt one will be the question I am asking, and the second one will be a worked question of similar nature that I missed. I will also post the refrences that I am using. Please use the numbers off those refernces or the answer will be wrong. Thanks

Missed:

Charts:

Ksp-

BromidesPbBr26.3 × 10-6

AgBr3.3 × 10-13CarbonatesBaCO38.1 × 10-9

CaCO33.8 × 10-9

CoCO38.0 × 10-13

CuCO32.5 × 10-10

FeCO33.5 × 10-11

PbCO31.5 × 10-13

MgCO34.0 × 10-5

MnCO31.8 × 10-11

NiCO36.6 × 10-9

Ag2CO38.1 × 10-12

ZnCO31.5 × 10-11ChloridesPbCl21.7 × 10-5

AgCl1.8 × 10-10ChromatesBaCrO42.0 × 10-10

CaCrO47.1 × 10-4

PbCrO41.8 × 10-14

Ag2CrO49.0 × 10-12CyanidesNi(CN)23.0 × 10-23

AgCN1.2 × 10-16

Zn(CN)28.0 × 10-12FluoridesBaF21.7 × 10-6

CaF23.9 × 10-11

PbF23.7 × 10-8

MgF26.4 × 10-9HydroxidesAgOH2.0 × 10-8

Al(OH)31.9 × 10-33

Ca(OH)27.9 × 10-6

Cr(OH)36.7 × 10-31

Co(OH)22.5 × 10-16

Cu(OH)21.6 × 10-19

Fe(OH)27.9 × 10-15

Fe(OH)36.3 × 10-38

Pb(OH)22.8 × 10-16

Mg(OH)21.5 × 10-11

Mn(OH)24.6 × 10-14

Ni(OH)22.8 × 10-16

Zn(OH)24.5 × 10-17IodidesPbI28.7 × 10-9

AgI1.5 × 10-16OxalatesBaC2O41.1 × 10-7

CaC2O42.3 × 10-9

MgC2O48.6 × 10-5PhosphatesAlPO41.3 × 10-20

Ba3(PO4)21.3 × 10-29

Ca3(PO4)21.0 × 10-25

CrPO42.4 × 10-23

Pb3(PO4)23.0 × 10-44

Ag3PO41.3 × 10-20

Zn3(PO4)29.1 × 10-33SulfatesBaSO41.1 × 10-10

CaSO42.4 × 10-5

PbSO41.8 × 10-8

Ag2SO41.7 × 10-5SulfidesCaS8 × 10-6

CoS5.9 × 10-21

CuS7.9 × 10-37

FeS4.9 × 10-18

Fe2S31.4 × 10-88

PbS3.2 × 10-28

MnS5.1 × 10-15

NiS3.0 × 10-21

Ag2S1.0 × 10-49

ZnS2.0 × 10-25SulfitesBaSO38.0 × 10-7

CaSO31.3 × 10-8

Ag2SO31.5 × 10-14

Ka&Kb-

Acetic acid

CH3COOH

1.8 × 10-5

Acetylsalicylic acid (aspirin)

HC9H7O4

3.0 × 10-4

Aluminum ion

Al(H2O)43+

1.2 × 10-5

Arsenic acid

H3AsO4

2.5 × 10-4

5.6 × 10-8

3.0 × 10-13

Ascorbic acid

H2C6H6O6

7.9 × 10-5

1.6 × 10-12

Benzoic acid

C6H5COOH

6.3 × 10-5

Carbonic acid

H2CO3

4.2 × 10-7

4.8 × 10-11

Ferric ion

Fe(H2O)63+

4.0 × 10-3

Formic acid

HCOOH

1.8 × 10-4

Hydrocyanic acid

HCN

4.0 × 10-10

Hydrofluoric acid

HF

7.2 × 10-4

Hydrogen peroxide

H2O2

2.4 × 10-12

Hydrosulfuric acid

H2S

1.0 × 10-7

1.0 × 10-19

Hypochlorous acid

HClO

3.5 × 10-8

Nitrous acid

HNO2

4.5 × 10-4

Oxalic acid

H2C2O4

5.9 × 10-2

6.4 × 10-5

Phenol

C6H5OH

1.0 × 10-10

Phosphoric acid

H3PO4

7.5 × 10-3

6.2 × 10-8

3.6 × 10-13

Sulfuric acid

H2SO4

very large

1.2 × 10-2

Sulfurous acid

H2SO3

1.7 × 10-2

6.4 × 10-8

Zinc ion

Zn(H2O)42+

2.5 × 10-10

Base

Formula

Kb

Ammonia

NH3

1.8 × 10-5

Aniline

C6H5NH2

7.4 × 10-10

Caffeine

C8H10N4O2

4.1 × 10-4

Codeine

C18H21O3N

8.9 × 10-7

Diethylamine

(C2H5)2NH

6.9 × 10-4

Dimethylamine

(CH3)2NH

5.9 × 10-4

Ethylamine

C2H5NH2

4.3 × 10-4

Hydroxylamine

NH2OH

9.1 × 10-9

Isoquinoline

C9H7N

2.5 × 10-9

Methylamine

CH3NH2

4.2 × 10-4

Morphine

C17H19O3N

7.4 × 10-7

Piperidine

C5H11N

1.3 × 10-3

Pyridine

C5H5N

1.5 × 10-9

Quinoline

C9H7N

6.3 × 10-10

Triethanolamine

C6H15O3N

5.8 × 10-7

Triethylamine

(C2H5)3N

5.2 × 10-4

Trimethylamine

(CH3)3N

6.3 × 10-5

Urea

N2H4CO

1.5 × 10-14

Acetic acid

CH3COOH

1.8 × 10-5

Acetylsalicylic acid (aspirin)

HC9H7O4

3.0 × 10-4

Aluminum ion

Al(H2O)43+

1.2 × 10-5

Arsenic acid

H3AsO4

2.5 × 10-4

5.6 × 10-8

3.0 × 10-13

Ascorbic acid

H2C6H6O6

7.9 × 10-5

1.6 × 10-12

Benzoic acid

C6H5COOH

6.3 × 10-5

Carbonic acid

H2CO3

4.2 × 10-7

4.8 × 10-11

Ferric ion

Fe(H2O)63+

4.0 × 10-3

Formic acid

HCOOH

1.8 × 10-4

Hydrocyanic acid

HCN

4.0 × 10-10

Hydrofluoric acid

HF

7.2 × 10-4

Hydrogen peroxide

H2O2

2.4 × 10-12

Hydrosulfuric acid

H2S

1.0 × 10-7

1.0 × 10-19

Hypochlorous acid

HClO

3.5 × 10-8

Nitrous acid

HNO2

4.5 × 10-4

Oxalic acid

H2C2O4

5.9 × 10-2

6.4 × 10-5

Phenol

C6H5OH

1.0 × 10-10

Phosphoric acid

H3PO4

7.5 × 10-3

6.2 × 10-8

3.6 × 10-13

Sulfuric acid

H2SO4

very large

1.2 × 10-2

Sulfurous acid

H2SO3

1.7 × 10-2

6.4 × 10-8

Zinc ion

Zn(H2O)42+

2.5 × 10-10

A solution contains 1.12x10 M aluminum nitrate and 1.16x10 Mbarium acetate Solid ammonium phosphate is added slowly to this mixture A. What is the formula of the substance that precipitates first? formula What is the concentration of phosphate ion when this precipitation first begins? [PO4 1

Explanation / Answer

the concentrations:

Al(NO3)3 = 1.12*10^-2

BaAc = 1.16*10^-2

Due to stoichiometry, find ion concentration:

[Al+3] = 1.12*10^-2 M

[Ba+2] =  1.16*10^-2

When we add NH4+ and PO4-3 ions:

Al3PO4 precipitates

Ba3(PO4)2 precipitates as well

Find Ksp data

AlPO4 = 1.3 × 10-20

Ba3(PO4)2 = 1.3 × 10-29

Identify the amount of PO4-3 required to precipitate each:

1.3*10^-20 = [Al+3](PO4-3)

1.3*10^-20 = (1.12*10^-2)(PO4-3)

[PO4-3] = (1.3*10^-20)/ (1.12*10^-2) = 1.160*10^-18 M

for

1.3*10^-29 = [Ba+2]^3 [PO4-3]^2

(1.3*10^-29) / (1.16*10^-2)^3 = S^2

S = ((1.3*10^-29) / (1.16*10^-2)^3) ^0.5 = 2.885*10^-12

Clearly, AlPO4 precipitates first

B)

find concentration of PO4-3 ion when this occurs:

from previous data:

[PO4-3] = (1.3*10^-20)/ (1.12*10^-2) = 1.160*10^-18 M

[PO4-3] = 1.160*10^-18 M

Related Questions

Navigate

• Browse (All)
• Browse #
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.