Question

A solution was prepared by dissolving 1210 mg of K3Fe(CN)6 (329.2 g/mol) in sufficient water to give 577 mL. Calculate the molar concentration of K+ .

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1 point
42.1 ×10+2 M K+
42.1 ×10-2 M K+
42.1 ×10 -3 M K+
1.91 ×10 -2 M K+

Answer 1

[AI-generated answer — Bot GPT 3.5]

To find the molarity of K+, we first need to calculate the moles of K3Fe(CN)6 using its molar mass and the given mass of 1210 mg:

Molar mass of K3Fe(CN)6 = 329.2 g/mol
Mass of K3Fe(CN)6 = 1210 mg = 1.21 g

Number of moles of K3Fe(CN)6 = Mass / Molar mass
Number of moles of K3Fe(CN)6 = 1.21 g / 329.2 g/mol = 0.003677 moles

Since there are 3 K+ ions in one formula unit of K3Fe(CN)6, the number of moles of K+ ions is:

Number of moles of K+ = 3 x Number of moles of K3Fe(CN)6
Number of moles of K+ = 3 x 0.003677 moles = 0.01103 moles

Now, we need to calculate the molarity of K+ by dividing the moles of K+ by the volume of the solution in liters:

Volume of solution = 577 mL = 0.577 L

Molarity of K+ = Number of moles of K+ / Volume of solution
Molarity of K+ = 0.01103 moles / 0.577 L = 0.0191 M

Therefore, the molar concentration of K+ is 1.91 ×10 -2 M K+.