A solution is prepared by combining 5.00 mL of 4.8x10-4 M NaSCN solution, 2.00 mL of 0.21 M Fe(NO3)3 solution and 13.00 mL of 0.3 M HNO3.

Calculate the analytical concentrations of SCN- and Fe3+ in the resulting solution.

Respuesta :

Answer:

The analytical concentrations of thiocyanate ions:

[tex][SCN^-]=0.00012 mol/L[/tex]

The analytical concentrations of ferric ions:

[tex][Fe^{3+}]=0.063 mol/L[/tex]

Explanation:

[tex]Moles (n)=Molarity(M)\times Volume (L)[/tex]

1) Moles of sodium thiocyanate  = n

Volume of sodium thiocyanate solution = 5.00 mL = 0.005 L

(1 mL = 0.001L)

Molarity of the sodium thiocyanate = [tex]4.8\times 10^{-4} M[/tex]

[tex]n=4.8\times 10^{-4} M\times 0.005 L=2.4\times 10^{-6}mol[/tex]

1 mole of sodium thiocyanate has 1 mol of thiocyante ions.

So, moles of thioscyanate ions in [tex]2.4\times 10^{-6}mol[/tex]  of NaSCN.

[tex]=1\times 2.4\times 10^{-6}mol=2.4\times 10^{-6}mol[/tex]

2) Moles of ferric nitrate = n'

Volume of ferric nitrate solution = 2.00 mL = 0.002 L

Molarity of the ferric nitrate = 0.21 M

[tex]n'=0.002 M\times 0.21 L=0.00042 mol[/tex]

1 mole of ferric nitrate has 3 moles of ferric ions.

So number of moles of ferric ions in 0.00042 moles of ferric nitrate is :

[tex]3\times 0.00042 mol=0.00126 mol[/tex]

Volume of nitric acid = 13.00 mL

Total volume by adding all three volumes of solutions = V

V = 5.00 mL + 2.00 mL + 13.00 mL = 20.00 mL = 0.020 L

The analytical concentrations of thiocyanate ions:

[tex][SCN^-]=\frac{2.4\times 10^{-6}mol}{0.020 L}=0.00012 mol/L[/tex]

The analytical concentrations of ferric ions:

[tex][Fe^{3+}]=\frac{0.00126 mol}{0.020 L}=0.063 mol/L[/tex]

Based on the data provided, the analytical concentrations of SC N⁻ and Fe³⁺ in the solution is 1.2 * 10⁻⁴ M and 2.4 * 10⁻² M.

What is the analytical concentration of  SC N⁻  and Fe³⁺ in the  solution?

The concentration of a solution is calculated using the formula below:

  • Concentration = moles/volume in L
  • moles = molarity * volume in L

The moles of the ions are first determined:

moles of NaSC N⁻  in 5.00 mL in 4.8 * 10⁻⁴ is calculated below:

moles of NaSC N⁻  = 0.005 * 4.8 * 10⁻⁴

moles of NaSC N⁻  = 2.4 * 10⁻⁶ moles

1 mole NaSC N ⁻  produces 1 mole SC N⁻

moles of SC N⁻ = 2.4 * 10⁻⁶ moles

moles of Fe(NO₃)₃ in 2.00 mL in 0.21 M solution is calculated below;

moles of Fe(NO₃)₃ = 0.002 * 0.21

moles of Fe(NO₃)₃ = 4.2 * 10⁻⁴ moles

1 mole Fe(NO₃)₃ produces 1 mole Fe³⁺

moles of Fe³⁺ = 4.2 * 10⁻⁴ moles

Total volume of solution = 0.002 + 0.005 + 0.013

Total volume of solution = 0.020 L

Concentration of SC N⁻ = 2.4 * 10⁻⁶/0.020

  • Concentration of SC N⁻ = 1.2 * 10⁻⁴ m

Concentration of Fe³⁺ = 4.2 * 10⁻⁴/0.02

  • Concentration of Fe³⁺ = 2.4 * 10⁻² M

Therefore, the analytical concentrations of SC N⁻ and Fe³⁺ in the solution is 1.2 * 10⁻⁴ M and 2.4 * 10⁻² M.

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