The empirical formula and molar mass of several compounds are listed. Find the molecular formula of each compound. a. C6H7N, 186.24 g>mol b. C2HCl, 181.44 g>mol c. C5H10NS2, 296.54 g>mol

Understanding the empirical formula calculation is fundamental in chemistry. An empirical formula represents the simplest whole-number ratio of the elements in a compound. To calculate it, one must first determine the percent composition of each element in the compound, which involves experimental data from elemental analysis. The steps generally include:

• Converting the percentage composition to grams (if not already in grams).
• Determining the moles of each element by dividing by the atomic masses from the periodic table.
• Finding the simplest whole-number mole ratio of the elements by dividing each element's moles by the smallest number of moles calculated.

If the ratios aren't whole numbers, they may be multiplied by the smallest common factor to convert them into whole numbers. This process yields the empirical formula, which is crucial as a starting point to determine the molecular formula.

Molar mass is a physical property defined as the mass of a given substance (chemical element or chemical compound) divided by the amount of substance. The molar mass of elements is found on the periodic table and is expressed in grams per mole (g/mol). It is calculated by summing the atomic masses of the atoms comprising a molecule. For a compound, the molar mass can be calculated by:

• Writing down the formula of the compound.
• Counting the number of atoms of each element in the formula.
• Looking up the atomic mass for each element on the periodic table.
• Multiplying the atomic mass of each element by the number of atoms of that element in the formula and adding up these quantities.

The knowledge of molar mass is not only essential for converting between mass and moles in chemical reactions but also as a stepping stone to deducing the molecular formula from the empirical formula.

The atomic masses of elements are standardized values that can be found on the periodic table. These values are averages that account for the varying isotopes of an element and their abundances and are fundamental for various calculations in chemistry. To use these atomic masses correctly, one should:

• Identify the specific element in question.
• Locate the element on the periodic table.
• Note the atomic mass listed, which is typically found beneath the symbol of the element.
• Use this atomic mass for calculations involving the element, such as determining the molar mass of compounds the element is part of.

The accuracy of the atomic masses is crucial since it affects the precision of empirical and molecular formula determinations, as well as stoichiometric calculations in chemical reactions.

Once the empirical formula and molar mass of a compound are known, the next step is to find the molecular formula. The molecular formula is the actual number of atoms of each element in a molecule, and it may be a multiple of the empirical formula. To identify this multiple, known as the molecular formula multiplier, the process involves:

• Calculating the molar mass of the empirical formula.
• Dividing the molar mass of the compound (often given) by the molar mass of the empirical formula.

The result is a number that usually needs to be rounded to the nearest whole number. This number will then multiply the subscripts in the empirical formula to give the molecular formula. It is important to note that the molecular formula multiplier determines how the empirical formula must be scaled to reflect the actual proportions of elements in the compound. This ties the empirical formula and molar mass concepts together, showcasing their interdependence in chemical calculations.