Significant figures are the digits in a number that carry meaning and contribute to its precision. There are rules for determining which digits are significant.
1. All non-zero digits are significant (e.g., 123 has 3 significant figures).
2. Any zeros between significant digits are also significant (e.g., 1002 has 4 significant figures).
3. Leading zeros are not significant (e.g., 0.0025 has 2 significant figures).
4. Trailing zeros are significant if there’s a decimal point (e.g., 2.340 has 4 significant figures).
In calculations, the precision of the result is determined by the number with the fewest significant figures. In our exercise:
- The mass of the oil (0.50 g) has 2 significant figures.
- The energy released (4.516 kcal) was rounded to 4.52 kcal for 3 significant figures.
Finally, the calculated caloric value per gram (9.032 kcal/g) should be rounded to the same number of significant figures as the least precise measurement in the calculation, resulting in:
9.0 kcal/g.
Understanding significant figures ensures that the precision of measurements is accurately reflected in the results.