Avogadro's law plays a significant role in reacting mass calculations, especially when dealing with gases. Avogadro's law states that equal volumes of all gases, at the same temperature and pressure, have the same number of molecules. This law is crucial for converting between volumes of gases and their corresponding moles in chemical reactions.

In reacting masses calculations involving gases, Avogadro's law allows us to directly relate the volume of a gas to the number of moles, given that the temperature and pressure are constant. For example, under standard conditions, one mole of any gas occupies 22.4 liters. If you know the volume of a gaseous reactant or product, you can use Avogadro's law to find the number of moles of that gas, and from there, apply stoichiometric principles to calculate the reacting masses of other reactants or products in the reaction.

This becomes particularly useful in scenarios where collecting and measuring the volume of a gas is more practical than weighing solid or liquid reactants or products. It also allows for the comparison and calculation of reacting masses of different gases in a reaction based on their volumes.

Temperature and pressure are significant factors in reactions involving gases. For solid and liquid reactants and products, changes in temperature and pressure usually have negligible effects on mass. However, for gases, these factors can significantly influence the volume, and thus indirectly affect the reacting masses when these are calculated using the gas laws. It's essential to understand this, especially when working with the Ideal Gas Law (PV=nRT), where P is pressure, V is volume, T is temperature, n is the number of moles, and R is the gas constant.

For instance, if you're calculating the reacting masses of substances involved in a gaseous reaction, the volume occupied by the gases (and thus the number of moles) will change with temperature and pressure. This means that to make accurate reacting mass calculations, you may need to first convert the volumes of gaseous reactants or products to standard temperature and pressure conditions (STP) using the gas laws, and then proceed with the stoichiometric calculations.

Disproportionation reactions are a type of redox reaction where a single substance is both oxidised and reduced, forming two different products. Handling reacting mass calculations in disproportionation reactions requires careful analysis of the reaction and understanding the stoichiometry involved.

In these reactions, you must consider the balanced chemical equation to determine the mole ratio between the reactant and each of the products. Even though a single reactant breaks down to form multiple products, the law of conservation of mass still applies. Here's how to approach it:

1. Balance the Equation: Ensure the chemical equation is balanced, including both mass and charge.
2. Determine the Moles of Reactant: Calculate the moles of the reactant using its mass and molar mass.
3. Apply Stoichiometry: Use the mole ratios from the balanced equation to determine the moles of each product formed.
4. Calculate the Masses of the Products: Convert the moles of each product back to mass using their respective molar masses.

For example, in the disproportionation of hydrogen peroxide (H₂O₂), it decomposes into water (H₂O) and oxygen (O₂). The balanced equation is: 2H₂O₂ → 2H₂O + O₂. To calculate the masses of water and oxygen produced from a known mass of H₂O₂, use the stoichiometric ratios from the balanced equation after converting the mass of H₂O₂ to moles.

Yes, reacting mass calculations can be employed to determine the purity of a substance. Purity in chemistry refers to the extent to which a substance is free from impurities. In a laboratory setting, you might have a sample of a substance that is not 100% pure and want to know its purity percentage. Here's how reacting mass calculations come into play:

1. Perform a Reaction: React the impure sample with a known quantity of another reactant in a reaction where the products and stoichiometry are known.
2. Calculate the Theoretical Yield: Using the mass of the pure substance (assuming 100% purity) and stoichiometry, calculate the theoretical yield of the product.
3. Measure the Actual Yield: Experimentally determine the actual yield of the product.
4. Calculate Purity: Purity (%) = (Actual yield / Theoretical yield) × 100.

For example, if you have an impure sample of a metal that reacts with an acid to produce a salt and hydrogen gas, by measuring the amount of salt or hydrogen produced, you can back-calculate the amount of pure metal that reacted, thus determining the sample's purity.

Identifying the limiting reactant in a reacting masses calculation is crucial for accurately determining the amount of product formed. To identify the limiting reactant, follow these steps:

1. Calculate the Moles of Each Reactant: Use the formula (number of moles = mass / molar mass) to find the moles of each reactant given their masses.
2. Use Stoichiometry: Refer to the balanced chemical equation and compare the mole ratios of the reactants.
3. Determine the Limiting Reactant: The reactant that produces the least amount of product (when the mole ratios are applied) is the limiting reactant. It's the substance that will be completely consumed first in the reaction.
4. Calculate the Product Mass Using the Limiting Reactant: Once the limiting reactant is identified, use its mole quantity to calculate the mass of the products.

For example, in a reaction where 2 moles of A react with 1 mole of B to produce C, if you start with 3 moles of A and 2 moles of B, A is in excess (would produce 1.5 moles of C), while B (would produce 2 moles of C) is the limiting reactant. The reaction will stop when B is completely used up.