Problem 88 - Chemistry The Science in Context

Question

CFCs (chlorofluorocarbons) are molecules used as refrigerants, but they also contribute to the destruction of the ozone layer. One CFC known as Freon consists of two carbon atoms, two fluorine atoms, and four chlorine atoms. What is the empirical formula of Freon? What is its molecular formula?

Step-by-Step Solution

Answer

Answer: The empirical formula of Freon is CFCl2, and its molecular formula is C2F2Cl4.

Step 1: Identify the number of each atom in the molecular formula

The molecular formula of Freon contains two carbon atoms, two fluorine atoms, and four chlorine atoms.

Step 2: Reduce the molecular formula to its simplest whole number ratio of elements to find the empirical formula

We can divide all the element counts by the lowest number (which is 2) to simplify the molecular formula and obtain the empirical formula: Carbon (C): 2 / 2 = 1 Fluorine (F): 2 / 2 = 1 Chlorine (Cl): 4 / 2 = 2 So, the empirical formula is: C1F1Cl2, which can be written as CFCl2.

Step 3: Determine the molecular formula

Since we already know the molecular formula contains two carbon atoms, two fluorine atoms, and four chlorine atoms, the molecular formula is C2F2Cl4. To conclude, the empirical formula of Freon is CFCl2, and its molecular formula is C2F2Cl4.

Key Concepts

Empirical Formula

The empirical formula of a chemical compound shows the simplest whole number ratio of the elements in that compound. It does not provide information on the actual number of atoms in the molecule, but it simplifies the proportions. For instance, for Freon in our example, which has two carbon, two fluorine, and four chlorine atoms, the empirical formula simplifies to CFCl extsubscript{2}. This reflects a simple 1:1:2 ratio.

• Empirical formulas are often used for ionic compounds and substances with repetitive chain units.
• They help chemists quickly determine the basic composition of a compound.

It is important to keep in mind that different compounds can have the same empirical formula but different molecular formulas.

Molecular Formula

The molecular formula of a compound provides the exact number of each type of atom present in a molecule. It is more specific than the empirical formula. For Freon, the molecular formula is C extsubscript{2}F extsubscript{2}Cl extsubscript{4}, indicating that each molecule contains two carbon, two fluorine, and four chlorine atoms.

• Molecular formulas help in understanding the structure of a compound. They show the actual number of atoms, allowing for analysis of molecular weight and more complex chemical behavior.
• While the molecular formula gives detailed information, it can be more complex and lengthy than the empirical formula.

Understanding this difference is crucial in predicting the properties and reactions of chemical substances.

CFCs (Chlorofluorocarbons)

Chlorofluorocarbons, known as CFCs, are compounds made up of chlorine, fluorine, and carbon. They have been widely used in industrial applications, such as refrigerants, propellants, and solvents. Their low toxicity and high efficiency made them popular choices until their environmental impact became evident.

• CFCs are stable in the lower atmosphere, which allows them to rise intact into the stratosphere.
• Due to their stability and longevity, CFCs have been found to travel thousands of kilometers, affecting areas far from their original release point.

The discovery of their role in ozone layer depletion has led to regulations and a search for safer alternatives.

Ozone Layer Destruction

The ozone layer is crucial for protecting Earth from harmful ultraviolet (UV) radiation. Unfortunately, CFCs have been identified as a major contributor to ozone layer destruction. In the stratosphere, ultraviolet rays break down CFC molecules, releasing chlorine atoms. This chlorine then interacts with ozone molecules, leading to the thinning of the ozone layer.

• One chlorine atom from CFCs can destroy thousands of ozone molecules, leading to significant ozone depletion over time.
• This process has contributed to phenomena such as the Antarctic ozone hole.

Efforts like the Montreal Protocol have been implemented to phase out the production of ozone-depleting substances, including CFCs, to protect and restore the ozone layer.