# Calculating the Formula of a Compound from Reacting Mass Data

## Calculating the Formula of a Compound from Reacting Mass Data

## Understanding the Concept

- The
**formula of a compound**can be deduced using the**masses of the reactants**. - This approach is based on the
**conservation of mass**principle, which states that the total mass of a chemical reaction’s reactants equals the total mass of products.

## Molar Ratios

- A chemical formula reflects the
**molar ratio of elements**in a compound. - The molar ratio is the ratio of the amounts (in moles) of each element in the reaction.

## Calculating Moles from Mass

- The
**number of moles**of a substance can be calculated from its mass using the formula:**Moles = Mass / Molar mass** - The molar mass (Mr) of an element or compound is the mass per mole.

## Balanced Equations and Molar Ratios

- A
**balanced chemical equation**provides the molar ratio between the reactants and products. - The
**coefficients (numbers in front of the reactants or products)**in a balanced chemical equation indicate this molar ratio.

## Determining the Chemical Formula

- Once the moles of each reactant are known, their
**simplest ratio**can be calculated to determine the formula. - It might be necessary to round to the nearest whole number, as chemical formulas must consist of integer values.

## Example of Calculations

- For instance, if 2.00 g of hydrogen reacts with 16.00 g of oxygen to produce water, the molar amounts will be 1.00 mol of hydrogen and 1.00 mol of oxygen since H₂’s molar mass is about 2 g/mol and O₂’s molar mass is about 32 g/mol.
- This provides a molar ratio of 1:1, producing the formula
**H₂O**.