When magnesium metal is burned in air, two product...

Question

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?

Jules Bruno · Accepted Answer

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:Mass percent = mass of componentmass of mixture×100 %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.[readmore]Step 1: Write an equation for the reaction of magnesium nitride with water.Magnesium nitride is an ionic compound because it is made from a metal (magnesium) and a nonmetal (nitrogen).The rules for naming ionic compounds with polyatomic ions are as follows:The metal keeps its name and is named and written first.For transition metals, we use Roman numerals to denote its charge.The nonmetal keeps its base name but has its ending change to –ide.Magnesium is a group 2A metal and forms a cation with a charge of +2: Mg2+Nitrogen is a nonmetal group 5A and forms an anion with a charge of -3: N3-The charges will crisscross: The reaction is:Mg3N2 + H2O → MgO + NH3This equation can be balanced by placing 3 with MgO, 3 with H2O and 2 with NH3.Mg3N2 + 3 H2O → 3 MgO + 2 NH3Step 2: Calculate the mass of magnesium oxide produced by reaction with water.When a 0.470 g mixture of Mg3N2 and MgO reacts with water, the final mass of MgO is 0.486 g. The mass of MgO that is produced by reaction with water is the difference of two masses.Mass of MgO produced = 0.486 g - 0.470 gMass of MgO produced = 0.016 gStep 3: Calculate the mass of magnesium nitride in the mixture.When the mixture reacts with water, 0.016 g of extra MgO is produced. This mass of MgO can be used to determine how much Mg3N2 was present in the mixture.From the balanced equation: 1 mol Mg3N2 produced 3 mol MgOWe will first need the molar masses of MgO and Mg3N2.Mg3N2             3 Mg × 24.30 g/mol = 72.90 g/mol                        2 N × 14.01 g/mol = 28.02 g/mol             _____________________________                                              Sum = 100.92 g/molMolar mass of Mg3N2 is 100.92 g/mol.MgO               1 Mg × 24.30 g/mol = 24.30 g/mol                       1 O × 16.00 g/mol = 16.00 g/mol            _____________________________                                             Sum = 40.30 g/molMolar mass of MgO is 40.30 g/mol.Mass of Mg3N2 in the mixtureMass of Mg3N2 = 0.016 g MgO×1 mol MgO40.30 g MgO×1 mol Mg3N23 mol MgO×100.92 g Mg3N21 mol Mg3N2Mass of Mg3N2 = 0.0134 gStep 4: Calculate the mass percent of magnesium nitride.The mass percent of Mg3N2in the mixture is:Mass percent of Mg3N2 = mass of Mg3N2mass of mixture×100 %Mass percent of Mg3N2 = 0.0134 g0.470 g×100 %Mass percent Mg3N2 = 2.85 %The mass percent of Mg3N2 in the initial mixture was 2.85 %.

FREE Expert Solution

Problem Details

FREE Expert Solution

Problem Details

Sign up for free to watch this video!