48g magnesium heated with 64g {{O}_{2(g)}}O2(g)​. Calculate the mass of the product formed.

Which is the limiting reagent and which is in excess?

To determine the mass of the product formed when magnesium reacts with oxygen, we first need to understand the chemical reaction involved. The reaction between magnesium and oxygen can be represented by the balanced equation:

Balanced Chemical Equation

The reaction is:

2 Mg (s) + O₂ (g) → 2 MgO (s)

This equation tells us that two moles of magnesium react with one mole of oxygen to produce two moles of magnesium oxide (MgO).

Calculating Moles of Reactants

Next, we need to calculate the number of moles of magnesium and oxygen we have:

• Molar mass of magnesium (Mg): 24.31 g/mol
• Molar mass of oxygen (O₂): 32.00 g/mol

Now, let's calculate the moles:

• Moles of magnesium:

  48 g Mg × (1 mol Mg / 24.31 g Mg) ≈ 1.97 mol Mg

• Moles of oxygen:

  64 g O₂ × (1 mol O₂ / 32.00 g O₂) = 2.00 mol O₂

Identifying the Limiting Reagent

To find out which reactant is the limiting reagent, we compare the mole ratio from the balanced equation with the moles we have:

According to the balanced equation, 2 moles of Mg react with 1 mole of O₂. Therefore, for 1.97 moles of Mg, we would need:

1.97 mol Mg × (1 mol O₂ / 2 mol Mg) = 0.985 mol O₂

Since we have 2.00 moles of O₂ available, which is more than the 0.985 moles required, magnesium is the limiting reagent. Oxygen is in excess.

Calculating the Mass of the Product

Now that we know magnesium is the limiting reagent, we can calculate the mass of magnesium oxide (MgO) produced:

From the balanced equation, 2 moles of Mg produce 2 moles of MgO. Therefore, 1.97 moles of Mg will produce 1.97 moles of MgO.

Now, we calculate the mass of MgO:

• Molar mass of magnesium oxide (MgO): 24.31 g/mol (Mg) + 16.00 g/mol (O) = 40.31 g/mol
• Mass of MgO produced:

  1.97 mol MgO × 40.31 g/mol ≈ 79.49 g MgO

Summary of Findings

In summary, the mass of magnesium oxide produced in this reaction is approximately 79.49 grams. Magnesium is the limiting reagent, while oxygen is in excess.