Now make up 1L stock solutions of each of the following Well

Now, make up 1L stock solutions of each of the following (We’ll skip the vitamins):

2.94 g NaF

17.4 g SrCl₂^.6H₂O

6.8 g KH₂PO₄

0.11 g FeCl₃^.6H₂O

0.012 g ZnSO₄^.7H₂O

0.04 g MnCl₂^.4H₂O

0.027 g Na₂MoO₄^.2H₂O

0.06 g CoCl₂^.6H₂O

0.025 g CuSO₄^.5H₂O

Add 1 mL each of the first 5 stock solutions to the seawater mixture above. Add 100 mL of the Mn, Zn, and Mo stock solutions to the seawater mixture above. Add 10 mL of the Co and Cu stock solutions to the seawater mixture above. What are the final concentrations of each trace element in the seawater solution (F, Sr, P, Fe, Zn, Mn, Mo, Co, and Cu (in mmol/L)? What is the amount of each of these constituents in g/kg? Do these concentrations seem about right?(20 points)

Solution

Below are concentrations in 1 L stock solution.

2.94 g NaF

17.4 g SrCl₂^.6H₂O

6.8 g KH₂PO₄

0.11 g FeCl₃^.6H₂O

0.012 g ZnSO₄^.7H₂O

0.04 g MnCl₂^.4H₂O

0.027 g Na₂MoO₄^.2H₂O

0.06 g CoCl₂^.6H₂O

0.025 g CuSO₄^.5H₂O

After addition of 1 mL of first 5 stock solutions we have,

2.94 mg NaF

17.4 mg SrCl₂^.6H₂O

6.8 mg KH₂PO₄

0.11 mg FeCl₃^.6H₂O

0.012 mg ZnSO₄^.7H₂O

After addition of 100 mL of Mn, Zn, Mo solutions we have,

2.94 mg NaF

17.4 mg SrCl₂^.6H₂O

6.8 mg KH₂PO₄

0.11 mg FeCl₃^.6H₂O

0.012 mg ZnSO₄^.7H₂O

0.004 g MnCl₂^.4H₂O

0.0012 g ZnSO₄^.7H₂O, Total = 0.001212 g

0.0027 g Na₂MoO₄^.2H₂O

After addition of 10 mL of Co, Cu solutions we have,

2.94 mg NaF

17.4 mg SrCl₂^.6H₂O

6.8 mg KH₂PO₄

0.11 mg FeCl₃^.6H₂O

0.004 g MnCl₂^.4H₂O

0.001212 g ZnSO₄^.7H₂O

0.0027 g Na₂MoO₄^.2H₂O

0.0006 g CoCl₂^.6H₂O

0.00025 g CuSO₄^.5H₂O

Total volume = 5 + 300 + 20 = 365 mL

Total mass = 36.012 mg

Below table gives concentrations of each substance:

Substance

Mass, mg

Molar Mass, g/mol

Moles, mmol

Concentration, mmol/L

Concentration, g/kg

NaF

2.94

42

0.07

0.192

81.6

SrCl2.6H2O

17.4

266.62

0.0653

0.179

483.2

KH2PO4

6.8

136

0.05

0.137

188.8

FeCl3.6H2O

0.11

270.29

0.0004

0.001

3.1

MnCl2.4H2O

4

197.91

0.0202

0.055

111.1

ZnSO4.7H2O

1.212

287.58

0.0042

0.012

33.7

Na2MoO4.2H2O

2.7

241.95

0.0112

0.031

75.0

CoCl2.6H2O

0.6

237.93

0.0025

0.007

16.7

CuSO4.5H2O

0.25

249.69

0.0010

0.003

6.9

Total

36.012

0.225

Substance	Mass, mg	Molar Mass, g/mol	Moles, mmol	Concentration, mmol/L	Concentration, g/kg
NaF	2.94	42	0.07	0.192	81.6
SrCl2.6H2O	17.4	266.62	0.0653	0.179	483.2
KH2PO4	6.8	136	0.05	0.137	188.8
FeCl3.6H2O	0.11	270.29	0.0004	0.001	3.1
MnCl2.4H2O	4	197.91	0.0202	0.055	111.1
ZnSO4.7H2O	1.212	287.58	0.0042	0.012	33.7
Na2MoO4.2H2O	2.7	241.95	0.0112	0.031	75.0
CoCl2.6H2O	0.6	237.93	0.0025	0.007	16.7
CuSO4.5H2O	0.25	249.69	0.0010	0.003	6.9
Total	36.012		0.225