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