Question

What masses of sodium chloride, magnesium chloride, sodium sulfate, calcium chloride, potassium chloride, and sodium bicarbonate are needed to produce 1 L of artificial seawater for an aquarium? The required ionic concentrations are [Na+] = 3.28 M; [K+] = 0.0094 M; [Mg2+] = 0.0693 M; [Ca2+] = 0.0115 M; [HCO3−] = 0.0015 M; [Cl−] = 3.32 M; [SO42−] = 0.0652 M.

Answer 1

Answer:

NaCl: 184g

MgCl₂: 6.60g

Na₂SO₄: 9.26g

CaCl₂: 1.28g

KCl: 0.70g

NaHCO₃: 0.13g

Explanation:

To convert these concentrations to masses we need to convert molarity to moles and moles to grams using molar mass of each salt:

[CaCl₂] = [Ca²⁺] = 0.0115M

[HCO₃⁻] = [NaHCO₃] = 0.0015M

[SO₄²⁻] = [Na₂SO₄] = 0.0652M

[Mg²⁺] = [MgCl₂] = 0.0693M

[K⁺] = [KCl] = 0.0094M

And using the concentration of Cl⁻:

[Cl⁻] = [NaCl] + 2[MgCl₂] + 2[CaCl₂] + [KCl]

[3.32] = [NaCl] + 2[0.0693] + 2[0.0115] + [0.0094]

[NaCl] = 3.149M

The masses you need are:

NaCl (Molar mass: 58.44g/mol):

3.149mol/L * 1L *  (58.44g/mol) =

184g NaCl

MgCl₂ (Molar mass: 95.211g/mol):

0.0693mol/L * 1L *  (95.211g/mol) =

6.60g MgCl₂

Na₂SO₄ (Molar mass: 142.04g/mol):

0.0652mol/L * 1L *  (142.04g/mol) =

9.26g Na₂SO₄

CaCl₂ (Molar mass: 110.98g/mol):

0.0115mol/L * 1L *  (110.98g/mol) =

1.28g CaCl₂

KCl (Molar mass: 74.55g/mol):

0.0094mol/L * 1L *  (74.55g/mol) =

0.70g KCl

NaHCO₃ (Molar mass: 84g/mol):

0.0015mol/L * 1L *  (84g/mol) =

0.13g NaHCO₃