wee the calculated masses of the anhydrous compound and water from at) and the i
ID: 531338 • Letter: W
Question
wee the calculated masses of the anhydrous compound and water from at) and the identity of the hydrated compound (on the provided data slip) to determine the formula of the hydrated compound. Mass of anhydrous compound (from #1) Mass of water lost (from #1): A. Calculate moles of the anhydrous compound: B. Calculate moles of water: C. Determine the simplest mole ratio to find the empirical formula: (Note: unlike with determining formulas for compounds, you may round to the nearest whole number for the moles of water in the hydrate) Formula of the hydrate: Mgso4' Hzo Slip Data for hydrate #2 (supplied on the data slip) 5. Hydrate #2: Mass of hydrate before heating Mass of residue after heating (a anhydrous compound) watery Loss of mass upon heating A. Calculate moles of the anhydrous compound: B. Calculate moles of water: C. Determine the simplest mole ratio to find the empirical formula: Formula of the hydrate: Mgso4Explanation / Answer
Mass of anhydrous compound= 5.3227 g
Grams of water lost by heating = 1.6494g
Molar mass of water =18.0g/mol
Molar mass of MgSO4 = 120.4 g/mol
A. Calculate moles of anhydrous compound-
Moles of anhydrous compound = mass of anhydrous compound / molar mass of anhydrous compound
Moles of anhydrate = 5.3227 g of MgSO4 / (120.4 g/mol MgSO4) = 0.0442 moles of MgSO4
B. Calculate moles of water-
Moles of water = 1.6494g of H2O/(18.0 g /mol H2O ) = 0.0908 moles H2O
C. Find the water-to-anhydrate mole ratio-
Divide moles of water by moles of anhydrate to get the mole ratio.
0.0908 moles of H2O/ 0.442 moles of MgSO4 = 2.054 = 2 (nearest whole number)
2 moles H2O / 1 mole MgSO4 = 2:1.
Now use the mole ratio to write the formula. Since there are 2 moles of H2O for every 1 mole of MgSO4,
So the formula of hydrate is MgSO4.2H2O
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