Question

There are two binary compounds of mercury and oxygen. Heating either of them results in the decomposition of the compound, with oxygen gas escaping into the atmosphere while leaving a residue of pure mercury. Heating \(0.6498 \mathrm{~g}\) of one of the compounds leaves a residue of \(0.6018 \mathrm{~g}\). Heating \(0.4172 \mathrm{~g}\) of the other compound results in a mass loss of \(0.016 \mathrm{~g}\). Determine the empirical formula of each compound.

Short answer

The empirical formulas of the two compounds are HgO for Compound 1 and Hg₂O for Compound 2.

Step-by-step solution

Compound 1: Calculate moles of Mercury

For Compound 1, the initial mass is 0.6498 g and the residue mass of Hg is 0.6018 g. To find the moles of Hg, divide the residue mass by the molar mass of Hg: moles of Hg = (0.6018 g) / (200.59 g/mol) = 0.003 mol

Compound 1: Calculate moles of Oxygen

For Compound 1, determine the mass of oxygen (O) by subtracting the residue mass of Hg from the initial mass: mass of O = (0.6498 g - 0.6018 g) = 0.048 g Next, calculate the moles of O by dividing the mass of O by the molar mass of O: moles of O = (0.048 g) / (16.00 g/mol) = 0.003 mol

Compound 1: Determine empirical formula

For Compound 1, the mole ratio of Hg to O is 1:1, since both have equal moles (0.003 mol). Therefore, the empirical formula of Compound 1 is HgO.

Compound 2: Calculate moles of Oxygen

For Compound 2, the mass loss after heating is 0.016 g. This mass loss corresponds to the mass of O. Determine the moles of O by dividing the mass of O by the molar mass of O: moles of O = (0.016 g) / (16.00 g/mol) = 0.001 mol

Compound 2: Calculate initial mass of Mercury

For Compound 2, determine the initial mass of Hg by subtracting the mass of O from the initial mass of the compound: Initial mass of Hg = (0.4172 g - 0.016 g) = 0.4012 g

Compound 2: Calculate moles of Mercury

To find the moles of Hg, divide the initial mass of Hg by the molar mass of Hg: moles of Hg = (0.4012 g) / (200.59 g/mol) = 0.002 mol

Compound 2: Determine empirical formula

For Compound 2, the mole ratio of Hg to O is 2:1, since the moles of Hg are twice the moles of O (0.002 mol : 0.001 mol). Therefore, the empirical formula of Compound 2 is Hg₂O. In conclusion, the empirical formulas of the two compounds are HgO for Compound 1 and Hg₂O for Compound 2.