Problem: When magnesium metal is burned in air, two products are produced. One is magnesium oxide, MgO. The other is the product of the reaction of Mg with molecular nitrogen, magnesium nitride. When water is added to magnesium nitride, it reacts to form magnesium oxide and ammonia gas.In an experiment a piece of magnesium ribbon is burned in air in a crucible. The mass of the mixture of MgO and magnesium nitride after burning is 0.470 g. Water is added to the crucible, further reaction occurs, and the crucible is heated to dryness until the final product is 0.486 g of MgO. What was the mass percentage of magnesium nitride in the mixture obtained after the initial burning?

We have to calculate the mass percentage of magnesium nitride in the mixture produced by burning magnesium metal in air.

When magnesium is burned in air, a mixture of magnesium oxide and magnesium nitride is produced. The mass percent of a component in a mixture is calculated by this formula:

$\boxed{\mathbf{Mass}\mathbf{ }\mathbf{percent}\mathbf{ }\mathbf{=}\mathbf{ }\frac{\mathbf{mass}\mathbf{ }\mathbf{of}\mathbf{ }\mathbf{component}}{\mathbf{mass}\mathbf{ }\mathbf{of}\mathbf{ }\mathbf{mixture}}\mathbf{\times }\mathbf{100}\mathbf{ }\mathbf{\%}}$

We need the mass of magnesium nitride that produced magnesium oxide upon reaction with water.

We will calculate it through these steps:

Step 1: Write an equation for the reaction of magnesium nitride with water.

Step 2: Calculate the mass of magnesium oxide produced by reaction with water.

Step 3: Calculate the mass of magnesium nitride in the mixture.

Step 4: Calculate the mass percent of magnesium nitride.