Question

During a synthesis reaction, 1.8 grams of magnesium reacted with 6.0 grams of oxygen. What is the maximum amount of magnesium oxide that can be produced during the reaction? Mg + O2 → MgO 2.2 grams 2.9 grams 3.4 grams 3.9 grams

Answer 1

Answer:

2.9 grams.

Explanation:

• From the balanced reaction:

Mg + 1/2O₂ → MgO,

1.0 mole of Mg reacts with 0.5 mole of oxygen to produce 1.0 mole of MgO.

• We need to calculate the no. of moles of (1.8 g) of Mg and (6.0 g) of oxygen:

no. of moles of Mg = mass/molar mass = (1.8 g)/(24.3 g/mol) = 0.074 mol.

no. of moles of O₂ = mass/molar mass = (6.0 g)/(16.0 g/mol) = 0.375 mol.

So. 0.074 mol of Mg reacts completely with (0.074/2 = 0.037 mol) of O₂ which be in excess.

Using cross multiplication:

1.0 mole of Mg produce → 1.0 mol of MgO.

∴ 0.074 mol of Mg produce → 0.074 mol of MgO.

∴ The amount of MgO produced = no. of moles x molar mass = (0.074 mol)(40.3 g/mol) = 2.98 g.