5. The argentometric gravimetric analysis of an alkaline earth metal chloride wa

Question

5. The argentometric gravimetric analysis of an alkaline earth metal chloride was conducted as usual (by dissolving the pure metal chloride in water, precipitating silver chloride, coagulating, filtering, and drying the colloid, and finally taking the mass of the solid.) Three samples of the metal chloride weighing 0.372, 0.365, 0.383 grams were analyzed giving 0.512, 0.503, 0.527 grams of silver chloride respectively. (That is, the first number in each set is one sample, the second is the next and the third number in each set is the third sample.) A.) Calculate the % chloride in the metal chloride samples. {Gravimetric Factor = 0.2474} B.) Which alkaline earth metal chloride is this? (Show how you determined your answer.)

Explanation / Answer

moles of Cl in,

sample 1 = 0.512 g/143.32 g/mol = 3.57 mmol

sample 2 = 0.503 g/143.32 g/mol = 3.50 mmol

sample 3 = 0.527 g/143.32 g/mol = 3.67 mmol

A) % Cl in metal chloride,

sample 1 = 3.57 mmol x 35.45 g/mol x 100/0.512 g = 24.7 %

sample 2 = 3.50 mmol x 35.45 g/mol x 100/0.503 g = 24.66 %

sample 3 = 3.67 mmol x 35.45 g/mol x 100/0.527 g = 24.69 %

B) The alkaline earth metal chloride = RaCl2

Only in RaCl2 the percentage Cl would be close to the value we have obtained.

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