How many \(g\) atoms of \(S\) are present in \(4.9 \mathrm{~g} \mathrm{H}_{2} \mathrm{SO}_{4} ?\)

Stoichiometry is a branch of chemistry that deals with the quantitative relationship between reactants and products in a chemical reaction. Think of it as a way of balancing a chemical budget, ensuring that the amount of substances going in matches what comes out.

When using stoichiometry in calculations, like the exercise we're examining, it's crucial to start with a balanced chemical equation. It gives you the ratios of how much of one substance reacts with another or is produced. This exercise didn't require balancing equations since we're only concerned with the composition of a single substance. However, the underlying principle of stoichiometry—that matter is conserved in a reaction and everything must be accounted for—still applies.

The mole concept is an essential part of chemistry that helps us count small particles like atoms, ions, and molecules using Avogadro's number \(6.022 \times 10^{23}\). A mole represents a standard quantity—the same number of units as there are atoms in exactly 12 grams of pure carbon-12.

When we say a substance has a molar mass of 98.09 g/mol, like \(H_2SO_4\) in our exercise, we're saying that one mole of \(H_2SO_4\) weighs 98.09 grams. By converting mass to moles or vice versa, we can relate our macroscopic experiments to the actions of atoms and molecules at the microscopic level.

Atomic mass is the mass of a single atom, usually expressed in atomic mass units (amu), where carbon-12 is defined as having an exact mass of 12 amu. This concept extends to 'grams per mole' when used in bulk calculations.

Each atom on the periodic table has a unique atomic mass, reflecting the combined number of protons and neutrons in its nucleus. For example, sulfur (S) has an atomic mass of roughly 32.07 g/mol. In the given exercise, knowing the atomic mass allows us to find the mass of sulfur in a compound by multiplying it with the number of moles of that element.

A chemical formula, such as \(H_2SO_4\), represents the actual number and types of atoms in a molecule. In a formula, the subscript numbers indicate how many of each atom are in the molecule, and if there's no number, it means there's just one atom of that kind.

From \(H_2SO_4\)'s chemical formula, we know it's composed of 2 hydrogen atoms, 1 sulfur atom, and 4 oxygen atoms. This information is crucial for calculating molar masses and carrying out stoichiometric conversions, like determining the mass of sulfur in a given mass of \(H_2SO_4\), which ties back to understanding the stoichiometry of the compound.