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Anonymous
Anonymous asked in Science & MathematicsChemistry · 1 day ago

A 5.00 g mixture of potassium sulfide and potassiumchloride contains 2.80g potassium What percentage by mass of mixture is potassium sulfide?

The answer is 19.2% I am just confused on how to get it so please include work. Thank you.

1 Answer

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  • 23 hours ago

    Let "z" be the mass (in grams) of K2S in the mixture.

    Then (5.00 - z) is the mass of KCl in the mixture.

    (z) g / (110.2616 g K2S/mol) x (2 mol K / 1 mol K2S) x (39.0983 g K/mol) =

    (0.709192 z) g K from K2S

    (5.00 - z) g / (74.5513 g KCl/mol) x (1 mol K / 1 mol KCl) x (39.0983 g K/mol) =

    (2.62224 - 0.524448 z) g K from KCl

    Set the sum of the two sources of K equal to the given total mass of K, all units in g:

    (0.709192 z) + (2.62224 - 0.524448 z) = 2.80

    Solve for z algebraically:

    z = 0.96220 g K2S

    (0.96220 g K2S) / (5.00 g total) = 0.19244 = 19.2% K2S by mass

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