When 0.55 grams of Magnesium is heated in a nitrogen atmosphere, a chemical reaction occurs. The product of the reaction weights 0.76 grams. Calculate the empirical formula of the compound containing Mg and N.

Mg₃N₂

Explanation:

The reaction of Mg + N₂ produces:

Mg + N₂ → MgₓNₙ

0.55g of Mg are:

0.55g ₓ (1 mol / 24.305g) = 0.0226 moles of Mg

Now, as the product has 0.76g of mass, mass of nitrogen is:

0.76g - 0.55g = 0.21g of N. In moles:

0.21g ₓ (1 mol / 14g) = 0.015 moles of N

The ratio in moles of N:Mg is:

0.0226 / 0.015 = 1.5. That means you have 1.5 atoms of Mg per atom of N. As empirical formula is the simplest whole-number ratio of atoms in a compound, empirical formula in the problem is:

Mg₃N₂

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.