Given that the molar mass of O_2 is 32.00 g/mol, how many moles of HgO are required to produce 250.0 g of O_2 according to the reaction 2 HgO → 2 Hg + O_2?

• A. 7.81 moles
• B. 15.6 moles
• C. 31.3 moles
• D. 3.91 moles

Answer: (B)

Verified step by step guidance

1. Write down the balanced chemical equation: 2 HgO \rightarrow 2 Hg + O_2.
2. Identify the molar masses: given that the molar mass of O_2 is 32.00 g/mol, find the molar mass of HgO (Mercury(II) oxide) by adding the atomic masses of Hg and O (Hg ≈ 200.59 g/mol, O ≈ 16.00 g/mol), so Molar mass of HgO = 200.59 + 16.00 = 216.59 g/mol.
3. Calculate the number of moles of O_2 produced from 250.0 g using the formula: moles of O_2 = mass of O_2 / molar mass of O_2 = 250.0 g / 32.00 g/mol.
4. Use the stoichiometric ratio from the balanced equation to relate moles of O_2 to moles of HgO. According to the equation, 1 mole of O_2 is produced from 2 moles of HgO, so moles of HgO = 2 × moles of O_2.
5. Multiply the moles of O_2 by 2 to find the moles of HgO required to produce 250.0 g of O_2.