The mass of initial magnesium metal used do not affect calculation of determining the empirical formula. Why? Explain in terms of chemical laws.
To understand why the mass of initial magnesium metal does not affect the calculation of determining the empirical formula, we need to consider the underlying chemical laws involved.
The empirical formula represents the simplest whole-number ratio of atoms present in a compound. It is determined through experimental data, particularly from the masses of the elements involved.
In the case of determining the empirical formula of magnesium oxide, for example, you would typically start with a known mass of magnesium metal and measure the mass of the magnesium oxide formed after it reacts with oxygen. By comparing these masses, you can calculate the ratio of magnesium to oxygen in the compound.
The reason why the initial mass of magnesium does not affect the empirical formula calculation lies in the Law of Conservation of Mass. This law states that mass cannot be created or destroyed in a chemical reaction; it is only transformed from one form to another.
During the reaction between magnesium and oxygen, the mass of the magnesium metal will be entirely converted into the mass of the resulting magnesium oxide. The ratio of magnesium to oxygen remains constant, regardless of the initial quantity of magnesium used.
For instance, if we consider a specific example where 4 grams of magnesium completely reacts with 2.7 grams of oxygen to form 6.7 grams of magnesium oxide, we can calculate the empirical formula by dividing the masses by their respective atomic weights (24.31 g/mol for Mg and 16.00 g/mol for O). In this case, we find that the ratio of magnesium to oxygen is approximately 1: 1.381.
However, if we were to use a different mass of magnesium initially, such as 2 grams, the ratio of magnesium to oxygen would still be the same (1: 1.381). The chemical reaction between magnesium and oxygen is independent of the initial mass of magnesium. Therefore, the mass of the initial magnesium metal does not affect the calculation of determining the empirical formula, as long as the reaction is complete and the Law of Conservation of Mass is observed.