Apparatus for empirical formula of MgO via combustion

Steps:

• Clean and dry a crucible and lid, then weigh them together to establish initial mass.
• Add a known mass of magnesium ribbon to the crucible, reweigh to find magnesium mass.
• Heat the crucible strongly using a Bunsen burner, lifting the lid periodically to allow oxygen access and prevent magnesium oxide escape.
• Cool, reweigh the final product, and calculate oxygen mass by difference to determine the Mg:O ratio.

Why D is correct:

• Options 2 (crucible) and 3 (lid) contain and control the reaction, essential for accurate mass measurements per conservation of mass.

Why the others are wrong:

• A includes 1 (likely Bunsen burner), but the question focuses on reaction vessel, not heat source.
• B pairs 1 and 2, omitting the lid needed to minimize oxide loss.
• C pairs 1 and 3, excluding the crucible required to hold the sample.

Final answer: D