Answer:
Mass of mercury produced = 2.00 g
Explanation:
At room temperature and pressure, the temperature T = 25° C or 298.15 K while the pressure = 1 atmosphere or 760 mmHg.
Mass of oxide of mercury decomposed at room temperature and pressure = 2.16 g
Volume of oxygen produced = 120 cm³ or 0.12 dm³
One mole of any gas has a volume of 24 dm³ at room temperature and pressure.
Therefore, number of moles of oxygen produced = 0.12 dm³ / 24 dm³/mol = 0.005 moles
Mass of oxygen produced = number of moles × molar mass
Molar mass of oxygen = 32 g/mol
Mass of oxygen produced = 0.005 moles × 32 g/mol = 0.16 g
Thus, mass of mercury produced = mass of mercury oxide decomposed - mass of oxygen produced
Mass of mercury produced = 2.16 g - 0.16 g
Mass of mercury produced = 2.00 g