Chemistry · Chemical equations and stoichiometry

How many grams of magnesium oxide is formed when 4.8 gm of magnesium is combined

How many grams of magnesium oxide is formed when 4.8 gm of magnesium is combined with \( 3.2 \mathrm{gm} \) of oxygen?

  • A. \( 4.2 \mathrm{gm} \)
  • B. 3.2 gm
  • C. 8 gm
  • D. \( 16 \mathrm{gm} \)

Step-by-step solution

Balanced equation: 2Mg + O2 → 2MgO. Moles Mg = 4.8 g / 24 g/mol = 0.2 mol; moles O2 = 3.2 g / 32 g/mol = 0.1 mol. Stoichiometric ratio 2:1 matches, so both are fully consumed. Moles MgO = moles Mg = 0.2 mol. Mass MgO = 0.2 mol × 40 g/mol = 8 g.
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