The Freons are a class of compounds containing carbon, chlorine, and fluorine. While they have many valuable uses, they have been shown to be responsible for depletion of the ozone in the upper atmosphere. In 1991 , two replacement compounds for Freons went into production: \(\mathrm{HFC}-134 \mathrm{a}\left(\mathrm{CH}_{2} \mathrm{FCF}_{3}\right)\) and \(\mathrm{HCFC}-124\) (CHCIFCF \(_{3}\) ). Calculate the molar masses of these two compounds.

Freons, a series of chlorofluorocarbons (CFCs), have historically played a significant role in various applications such as refrigerants, propellants in aerosol sprays, and solvents. However, these compounds are now infamous for their environmental impact, specifically their potential to deplete the stratospheric ozone layer.

Their stability was once prized, but it is this very characteristic that allows them to persist long enough to reach the upper atmosphere, where they release chlorine atoms through photodissociation. These chlorine atoms act as catalysts in the breakdown of ozone molecules, contributing to the ozone hole and increased ultraviolet radiation reaching the Earth's surface, which poses a threat to both human health and the environment.

The depletion of the ozone layer is a significant global concern. The ozone layer, located within the stratosphere, acts as Earth's natural sunscreen by absorbing the majority of the sun's harmful ultraviolet (UV) radiation. When Freons and other CFCs reach the stratosphere, they are broken down by UV light, releasing chlorine atoms. A single chlorine atom can destroy thousands of ozone molecules before it is removed from the stratosphere, leading to increased UV radiation at ground level, which can cause skin cancer, cataracts, and have adverse effects on the environment and wildlife.

The periodic table of elements is a tabular display crucial for understanding chemical properties and relationships among elements. It organizes elements by increasing atomic number and aligns them into groups and periods based on recurring chemical properties. For molar mass calculations, it serves as a reference to find atomic masses, a fundamental parameter required to calculate the molar mass of chemical compounds.

Being familiar with the periodic table allows students and chemists to quickly determine the proportionate weights of different atoms and use these figures to determine the weights of various chemical substances, as shown in the step-by-step solution for Freons and their replacements.

Atomic mass, often listed as the atomic weight on the periodic table, represents the average mass of atoms of an element, measured in atomic mass unit (amu). For an element with multiple isotopes, atomic mass is a weighted average reflecting the natural abundance of those isotopes.

In the context of the exercise, knowledge of atomic masses allows us to calculate the molar mass of chemical compounds, which is the mass of one mole of that substance. By summing the atomic masses of all atoms in the molecule, we get the molecular weight, an essential value for understanding chemical amounts and reactions. For instance, the precise calculation of the molar mass for HFC-134a and HCFC-124 uses the atomic mass of each element involved, reflecting the molecular composition of each compound.