Question

prepared a solution of potassium chloride by mixing 3.23 g of salt water. (05) Find : [ Atomic mass of K= 40 g, Cl = 35.5 g ] C1 g a) Formula unit mass of potassium chloride. b) Number of moles of potassium chloride dissolved in water. c) the number of potassium ions in 0.224 g of its hydroxide. ​

Answer 1

a) 75.5 amu

b) 0.042 moles

c) 0.11 g

Explanation:

Given:  Atomic mass of K= 40 g, Cl = 35.5 g, KCl = 3.23 g

a) Formula unit mass of potassium chloride:

We know that potassium chloride contains potassium and chlorine.

Hence KCl = 40 + 35.5 = 75.5 amu

b) Number of moles of potassium chloride dissolved in water:

Number of moles = mass/ molar mass

                              = 3.23 / 75.5

                              = 0.042 Moles

c) the number of potassium ions in 0.224 g of its hydroxide:

KOH → K⁺ + OH⁻

75.5 g of KOH contains 40 g of K⁺

∴ 0.224 g of KOH will contain x g of K⁺

∴ x = 40 × 0.224/ 75.5

     = 0.11 g of Potassium ions