In the reaction 2Mg + O2 -> 2MgO (Mg = 24, MgO = 40 g/mol), what mass of MgO forms from 24 g of magnesium?
Answer and explanation
Correct answer: C. 40 g
- Step 1: Moles of Mg = 24 / 24 = 1 mol, and 2 mol Mg gives 2 mol MgO.
- Step 2: Mass of MgO = 1 x 40 = 40 g.
Answer
40 g.
Why not the others: '24 g' assumes the product has the same mass as the metal; '14.4 g' inverts the mass ratio; '80 g' doubles the mass using the coefficient 2 twice.
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