Which of the following is the correct formula for percent error in a chemical experiment?

• A. ( measuredext{ }value + acceptedext{ }value ) / 2 imes 100ext{ %}
• B. ( |experimentalext{ }value - theoreticalext{ }value| ) / |theoreticalext{ }value| imes 100ext{ %}
• C. ( theoreticalext{ }yield - actualext{ }yield ) / actualext{ }yield imes 100ext{ %}
• D. ( actualext{ }yield / theoreticalext{ }yield ) imes 100ext{ %}

Answer: (B)

Verified step by step guidance

1. Understand that percent error is a way to express how far an experimental (measured) value is from a theoretical (accepted) value, relative to the theoretical value, usually expressed as a percentage.
2. Recall the general formula for percent error: it involves the absolute difference between the experimental value and the theoretical value, divided by the theoretical value, then multiplied by 100 to convert it to a percentage.
3. Write the formula mathematically as: \(\text{Percent Error} = \frac{ | \text{experimental value} - \text{theoretical value} | }{ | \text{theoretical value} | } \times 100\%\)
4. Note that the absolute value ensures the error is always positive, regardless of whether the experimental value is higher or lower than the theoretical value.
5. Recognize that other given formulas do not correctly represent percent error because they either average values, do not use absolute values, or use incorrect denominators.