Problem 24 - Chemistry in Context

Question

Platinum, palladium, and rhodium are used in the catalytic converters of cars. a. Give the chemical symbol for each metal. b. Locate each metal on the periodic table. c. What can you infer about the properties of these metals, given that they are useful in this application?

Step-by-Step Solution

Answer

Pt, Pd, Rh; transition metals with catalytic properties for emission reduction.

Step 1: Identifying Chemical Symbols

The chemical symbol for platinum is Pt, for palladium is Pd, and for rhodium is Rh. These symbols are derived from their respective names and are used universally to represent these elements in chemical equations and references.

Step 2: Locating the Metals on the Periodic Table

Find these metals in the 10th group of the periodic table. Platinum (Pt) is at atomic number 78, palladium (Pd) is at atomic number 46, and rhodium (Rh) is at atomic number 45. All are transition metals located in period 5 or 6 of the periodic table.

Step 3: Infer Properties from Periodic Table

As transition metals, these elements have partially filled d-orbitals which give them properties such as good conductivity, high melting points, and the ability to catalyze chemical reactions. These properties make them suitable for use in catalytic converters to reduce vehicle emissions effectively.

Key Concepts

Catalytic Converters

Catalytic converters are essential components in car exhaust systems. They help reduce harmful emissions. These devices convert toxic gases from vehicles into less harmful substances. A catalytic converter uses a catalyst, often containing transition metals like platinum, palladium, and rhodium. Consider the role of these metals in the converter:

• They facilitate chemical reactions that transform pollutants.
• The metals do not undergo permanent changes during this process; they merely act as catalysts.
• They help convert carbon monoxide, nitrogen oxides, and hydrocarbons into water vapor, nitrogen gas, and carbon dioxide.

This is crucial for minimizing environmental pollution and is one reason why these metals are so valuable.

Chemical Symbols

Chemical symbols are shorthand representations used universally for elements. They usually consist of one or two letters derived from the element's English or Latin name. For instance:

• Platinum is represented as Pt.
• Palladium is known as Pd.
• Rhodium is referred to as Rh.

These symbols simplify writing chemical equations and speaking about elements without confusion. They facilitate international communication in the scientific community, ensuring consistency and clarity in research and application.

Periodic Table

The periodic table organizes all known elements in a systematic way. It helps scientists quickly find information about the elements' properties and relationships. Each element's position tells us about its atomic structure and chemical behavior. Platinum, palladium, and rhodium are located in the d-block, known as the transition metals section. Here’s where to find them:

• Platinum (Pt): Atomic number 78, period 6, group 10.
• Palladium (Pd): Atomic number 46, period 5, group 10.
• Rhodium (Rh): Atomic number 45, period 5, group 9.

These elements are part of the same group, indicating similar properties such as forming colored compounds, and having high melting points and stability.

Properties of Metals

Metals, especially transition metals, have distinct properties that make them useful in various applications, including catalytic converters. Key properties include:

• Conductivity: They conduct electricity and heat efficiently, crucial for facilitating reactions in converters.
• High Melting Points: This means they can withstand high temperatures typical in automobile exhaust systems without degrading.
• Ability to Catalyze Reactions: Due to their partially filled d-orbitals, transition metals can reduce activation energies for reactions, speeding up the conversion of pollutants in the exhaust.

These attributes allow these metals to perform exceptionally as part of the catalytic converter, minimizing vehicle emissions and contributing to air quality improvement.