A 1.42-g sample of a pure compound, with formula M2SO4, was dissolved in water and treated with an excess of aqueous calcium chloride, resulting in the precipitation of all the sulfate ions as calcium sulfate. The precipitate was collected, dried, and found to weigh 1.36 g. Determine the atomic mass of M, and identify M.

Question

Physics

Randolph

8 February, 17:17

A 1.42-g sample of a pure compound, with formula M2SO4, was dissolved in water and treated with an excess of aqueous calcium chloride, resulting in the precipitation of all the sulfate ions as calcium sulfate. The precipitate was collected, dried, and found to weigh 1.36 g. Determine the atomic mass of M, and identify M.

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Answers (1)

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Xavier · Answer 1

M2SO4 + CaCl2 = 2MCl + CaSO4

(2M + 32 + 64) g (40 + 32 + 64) g

(2M + 96) g of sample makes 136 g of calcium sulfate

1.42 g will make (136 x 1.42) / (2M + 96) g

Given,

(136x 1.42) / (2M + 96) = 1.36

M = 23

It is sodium.