Significant figures, also known as significant digits, are the digits that represent the accuracy or precision of a measurement in chemistry. They are used to indicate the degree of certainty in a measurement and are important for reporting and communicating experimental results.
The general rule for determining the number of significant figures in a measurement is to count all non-zero digits and any zeros between non-zero digits. For example, the measurement 3.45 has three significant figures, while 0.005 has one significant figure. However, there are some exceptions and more specific rules to follow, so it is important to consult a comprehensive guide for more accurate determinations.
Significant figures are important in chemistry because they help to convey the precision and accuracy of experimental results. Using the correct number of significant figures prevents misleading or incorrect conclusions from being drawn from experimental data. They are also crucial for performing calculations with measurements, as the number of significant figures in the final answer should match the least precise measurement used in the calculation.
Yes, significant figures can be rounded. When rounding a number to a specified number of significant figures, the following rules apply: if the digit to be dropped is less than 5, the preceding digit remains the same; if the digit to be dropped is 5 or greater, the preceding digit is increased by one. For example, rounding 3.456 to two significant figures results in 3.5, and rounding 4.394 to three significant figures results in 4.39.
When performing calculations with measurements, the final answer should have the same number of significant figures as the least precise measurement used in the calculation. For addition and subtraction, the answer should be rounded to the least number of decimal places in any of the measurements. For multiplication and division, the answer should be rounded to the least number of significant figures in any of the measurements. It is also important to carry extra digits throughout the calculation and round only at the end to avoid errors.