Determine the number of moles of hydrogen atoms in each sample. a. 0.0885 mol C4H10 b. 1.3 mol CH4 c. 2.4 mol C6H12 d. 1.87 mol C8H18

Stoichiometry can be likened to a recipe in cooking—it tells you the amounts of each ingredient (reactants) needed to make the final product (products) in a chemical reaction. It involves the quantitative relationships between reactants and products in chemical processes and is based on the conservation of mass.

To fully appreciate stoichiometry, imagine each chemical equation as a balanced scale. On one side, you have the reactants, while the products are on the other. Their relationship is dictated by the coefficients in the balanced equation, which represent the ‘parts’ needed to react completely. Stoichiometry helps us calculate these proportions and translate them into real quantities, like the number of moles in the given problem.

Application to Hydrogen Atoms

In our exercise, stoichiometry allows us to use the coefficient (the subscript number in the chemical formula) next to hydrogen to determine how many parts of hydrogen are present per part of the compound. This is essential for calculating the moles of hydrogen atoms in the samples provided.

The mole concept is a gateway to the molecular world, fundamentally bridging the gap between the mass of substances on the macroscopic scale and the count of atoms or molecules on the microscopic scale. A mole, abbreviated as 'mol,' is Avogadro’s number (approximately 6.022 x 10^23) of things, typically atoms or molecules.

In practice, the mole concept allows chemists to count particles by weighing. This is crucial because individual atoms and molecules are far too small to count individually. Hence, by knowing the molar mass of a compound, which is the mass of one mole of that substance, we can convert between mass and number of moles. In our exercise, the initial step was to understand the number of moles given for the compound, which becomes the basis to find out the number of moles of a specific element within the compound.

From Compound to Atoms

With this concept, we look closely at the compounds provided – for example, butane (C4H10) – and recognize that one mole of butane means there must be 10 moles of hydrogen atoms bonding in butane's structure. This multiplication factor is essential for our calculations.

Chemical formulas represent compounds through symbols and subscript numbers indicating the types of atoms present and their relative amounts in a single molecule of the compound. They provide a significant amount of information at a glance, crucial for conducting stoichiometric calculations.

For instance, the formula C4H10 for butane notifies us that each molecule of butane contains four carbon atoms (C) and ten hydrogen atoms (H). These subscripts become multipliers when determining the amount of an individual element. When calculating moles of hydrogen atoms from a mole of compound, the subscript is our key indicator of the ratio that we use to multiply the number of moles of the entire compound to get the number of moles of hydrogen atoms, as seen in the provided step-by-step solution.

Understanding Ratios

Chemical formulas tell us the fixed ratio in which elements combine. By understanding these ratios, we can determine the proportion of each element within a compound and make precise calculations about the quantity of each within a given sample.

Avogadro’s number, a constant named after the scientist Amedeo Avogadro, is defined as the number of constituent particles, usually atoms or molecules, that are contained in one mole of a substance. Its value is approximately 6.022 x 10^23 and it’s a cornerstone of the mole concept.

The profound significance of Avogadro's number is its role in converting between the atomic scale and the macroscopic scale. If we know the number of moles of a substance, we can find out the actual number of particles by multiplying by Avogadro's number. Conversely, if we have the number of particles, we can calculate moles by dividing by this constant.

Relating to Hydrogen Atoms

In the context of our exercise, while Avogadro's number wasn't used directly, it underpins the concept that if we have a known quantity of moles of hydrogen, we inherently have a specific number of hydrogen atoms. Avogadro's constant assures us that this translation from moles to particles is accurate and allows scientists to make predictions about the physical quantities of substances in the real world.