In medicine it is sometimes necessary to prepare solutions with a specific concentration of a given ion. A lab technician has made up 100.0 mL of a solution containing 0.50 g of NaCl and 0.30 g of KCl, as well as glucose and other sugars. What is the concentration of chloride ions in the solution?

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Chemistry

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4 February, 16:16

In medicine it is sometimes necessary to prepare solutions with a specific concentration of a given ion. A lab technician has made up 100.0 mL of a solution containing 0.50 g of NaCl and 0.30 g of KCl, as well as glucose and other sugars. What is the concentration of chloride ions in the solution?

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Chaya · Answer 1

0.126 mol/L

Explanation:

The chloride ions come to the salts NaCl and KCl, which dissociates completely in water. So let's calculated how much moles of Cl⁻ are formed for each salt, knowing that the molar masses are Cl = 35.5 g/mol, Na = 23 g/mol, and K = 39 g/mol.

MNaCl = 23 + 35.5 = 58.5 g/mol

MKCl = 39 + 35.5 = 74.5 g/mol

The number of moles is the mass divided by the molar mass, and 1 mol of the salts produces 1 mol of Cl⁻:

nNaCl = 0.50/58.5 = 8.55x10⁻³ mol

nKCl = 0.30/74.5 = 4.03x10⁻³ mol

nCl⁻ = 8.55x10⁻³ + 4.03x10⁻³ = 0.01258 mol

The molar concentration is the number of moles divided by the solution volume (100 mL = 0.1 L):

0.01258/0.1 = 0.126 mol/L