Which statement best describes the relationship between an equality and a conversion factor in chemistry?

• A. An equality is a mathematical equation that only applies to chemical reactions and cannot be used for unit conversions.
• B. A conversion factor is always written as a percentage, and an equality is not needed to create it.
• C. An equality is used to balance chemical equations, while conversion factors are used to calculate molar mass.
• D. An equality shows that two different units represent the same quantity, and it is used to write a conversion factor as a ratio for unit conversion.

Answer: (D)

Verified step by step guidance

1. Understand that an equality in chemistry is a statement that two different units represent the same quantity. For example, 1 inch = 2.54 centimeters is an equality because both sides describe the same length.
2. Recognize that a conversion factor is derived from an equality and is expressed as a ratio of equivalent units. For example, from the equality 1 inch = 2.54 cm, you can write conversion factors as \( \frac{1 \text{ inch}}{2.54 \text{ cm}} \) or \( \frac{2.54 \text{ cm}}{1 \text{ inch}} \).
3. Note that conversion factors are used to convert a measurement from one unit to another by multiplying by the appropriate ratio, ensuring the units cancel correctly.
4. Clarify that equalities are not limited to chemical reactions; they are fundamental relationships between units that allow for unit conversions in many contexts, including chemistry.
5. Summarize that the best description is: an equality shows two units represent the same quantity, and it is used to write conversion factors as ratios for unit conversion.