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7. Apply guidelines on reporting significant figures in graph interpretation. 8. Use significant figures as a quality control objective. 9. Aspire to improve the quality of scientific meaning and decision making by properly determining, reporting, and interpreting significant figures in measurements and their calculated values. 10.
The following rules apply to calculations with significant figures: 1. Exact physical and mathematical constants and defined conversion factors (π, 1 inch = 2.54cm, 1kg = 1000g) and integer coefficients (like the 2 in “2πr”) have an infinite number of significant figures. 2.
When adding or subtracting two approximately known numbers, the number of significant figures in the result is determined by writing it with the same number of digits to the right of the decimal points as the factor with the smallest number of digits to the right of the decimal point. Here are some examples. 1.23 + 0.9 = 2.1.
Any number used in a calculation should contain only figures that are considered reliable; otherwise, time and effort are wasted. Figures that are considered reliable are called significant figures. Chemical calculations involve numbers representing actual measurements.
BASIC RULES FOR SIGNIFICANT FIGURES. This is just a summary of the rules for significant figures. For deeper explanations, more examples, and extra practice with these rules, please see the “Significant figures review” from the course website.
The significant figure rules are outlined below. We will apply these significant figure rules in all subsequent lab reports, in General Chemistry lecture courses on exams and homework and in all subsequent problems in your chemistry courses in both laboratory and lecture.
In a measurement, significant figures in a number consist of: Figures (digits) definitely known + One estimated figure (digit) In class you will hear this expressed as "all of the digits known for certain plus one that is a guess." Recording Measurements.
