Determine the empiricular formula of potassium oxide. The molar mass of potassium is 39.10 g/mol?
mass of crucible cover and K g 28.709
mass of crucible cover, and Potassium oxide g 28.793
Answer:
So, the mass of potassium is the mass of K + crucible less mass of crucible, or 28.709g - 28.288g = 0.421g
The mass of oxide is mass of crucible, K, and O less mass of crucible and K, or 28.793g - 28.709g = 0.084g.
Next we need to get the number of moles of each, first we need the molecular weights.
K (given) - 39.10 g/mol
O (approx) 16 g/mol
So, getting number of moles:
K = 0.421g / 39.10 g/mol = 0.0108 mol
O = 0.084g / 16 g/mol = 0.00525 mol
The ratio of number of moles of K to O is 0.0108 / 0.00525 = 2.06, which is close enough to 2.
Therefore, you have 2 moles of K for every mole of O, or K2O for your formula.
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