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From the data, predict the simplest ratio of metal atoms : oxygen atoms.
Calculation Steps
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Aim: To determine the simplest whole-number ratio of elements in a compound using experimental mass data.
Method: (1) Heat a known mass of metal in oxygen → (2) Weigh the oxide formed → (3) Calculate moles of metal and oxygen → (4) Find simplest ratio.
Example: Heating Mg in air: 2Mg + O₂ → 2MgO. If 2.4 g Mg gives 4.0 g MgO, oxygen = 1.6 g. Moles Mg = 2.4/24 = 0.1. Moles O = 1.6/16 = 0.1. Ratio = 1:1 → MgO.
• The crucible, lid and pipeclay triangle get very hot — handle only with tongs and let them cool before weighing.
• Burning magnesium gives an intense UV-rich white flame — never look at it directly; lift the lid only briefly to admit air (avoids losing white MgO smoke and improves accuracy).
• Metal-oxide powders (CuO, Fe₂O₃, MgO) are irritant dusts — avoid inhaling; wash hands after.
• Heat strongly over a Bunsen — tie back hair, wear goggles, and use a heat-proof mat.
• Repeat "heat–cool–weigh" until the mass is constant, so all the metal has reacted.
From the data, predict the simplest ratio of metal atoms : oxygen atoms.