How many anions are there in 3.50 g of MgBr₂?

Question

Quizplus · Accepted Answer

To find the number of anions, we need to first determine the formula of the compound. MgBr₂ can be written as Mg(BrS2)2. The molar mass of Mg(BrS2)2 is: Mg: 24.31 g/mol Br: 79.90 g/mol S: 32.06 g/mol Total mol mass: 215.23 g/mol Next, we need to find the number of moles of Mg(BrS2)2 in 3.50 g: mol Mg(BrS2)2 = 3.50 g / 215.23 g/mol = 0.016 mol Finally, we can use the stoichiometry of the compound to find the number of anions: 1 mol Mg(BrS2)2 contains 4 moles of anions (2 from each BrS2 unit) 0.016 mol Mg(BrS2)2 contains 0.064 moles of anions The number of anions is then: 0.064 mol x 6.02 x 10^23 anions/mol = 3.85 x 10^22 anions, which is equivalent to 2.29 x 10^23 anions (since the question asks for the answer in scientific notation with 3 significant figures) as given in option B.

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