The chemical equation shows the burning of magnesium Mg with oxygen open paren cap o sub 2 close paren to form magnesium oxide MgO 2 Mg plus cap o sub 2 rightarrow 2 MgO Niven wants to calculate the mass of MgO that is produced by the burning of 28 point 0 g of Mg What is the first step in Niven’s calculation?
Answer
A
Determine whether heat is given off by this reaction.
B
Balance the chemical equation.
C
Convert grams of Mg to moles.
D
Find the number of Mg atoms in the sample.
Explanation
The equation is already balanced: 2 Mg + O₂ → 2 MgO. To calculate the mass of MgO from a given mass of Mg, first convert 28.0 g of Mg to moles using magnesium’s molar mass. Then the balanced equation gives the mole ratio needed to find moles of MgO, which can be converted to grams.
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