No one will argue that determining the number of significant figures and keeping with the rules of those “sigfigs” throughout an already strenuous calculation can be a pain. Countless points and half-points have been deducted from tests throughout chemistry’s ages from students claiming that significant figures are, ironically, insignificant. But, let’s consider the following scenario. Joey is in his inorganic chemistry lab. The second step to the lab tells him to measure out the mass of Iron he had calculated in the pre-lab. The calculation had only called for 2 significant figures in the answer for the mass. Insted, he disregarded the rules and calculated the mass to 5 significant figures. He spent (and wasted) hours of his time trying to
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Measuring to the thousandths digit or to just the ones digit of the mL on a graduated cylinder with markings to the tenths of a mL would be incorrect. You know more specificity of the measurement than the ones digit but not as much as the thousandths digit.
To begin, there are two main categories of numbers, and several subcategories. Defined and counted numbers (Category 1) are exact and therefore have infinite significant figures. A defined number is one that is arbitrarily chosen (like 6 cm) or one that has been invented (like 60 minutes in an hour). Counted numbers are numbers that are obtained by changing discrete physical objects (like 4 cars in the driveway).
Measured numbers (Category 2) are all numbers that have been measured (like 4.5 mL of water in a graduated cylinder). They are inexact, and therefore, the rules of significant figures must be followed. When measuring a substance, you must record to the digit that varies + or – 1. For example, when using a mass, you would record a substance as 4.25 grams if the scale varied between 4.24 [g], 4.25 [g], and 4.26 …show more content…
This measured quantity has 2 significant digits—the 3 and the 4. The zeros are not significant because they are leading.
B. This measured quantity has 4 significant digits—the 1, 5, and both 0’s. The zeros are significant because they are trailing and there are digits following the decimal point
C. This measured quantity has an ambiguous number of significant figures, because there is not decimal point following the zero. However, we can assume that there are only 2 significant digits—the 1 and 2.
Significant figures must also be taken into consideration while performing calculations with measured numbers. In addition or subtraction problems, the answer must be answered to the same DECIMAL PLACE as the number in the equation with the least specific decimal place. In multiplication and division problems, the answer must have the same number of significant digits as the number in the equation with the fewest significant figures. These considerations must be taken into account so that the answer is no more precise than the measured quantities which the answer is based on. If the equation is multiple steps long, we must be careful not to decrease the number of significant figures while conducting the equation—only at the end when the answer has been
Measuring to the thousandths digit or to just the ones digit of the mL on a graduated cylinder with markings to the tenths of a mL would be incorrect. You know more specificity of the measurement than the ones digit but not as much as the thousandths digit.
To begin, there are two main categories of numbers, and several subcategories. Defined and counted numbers (Category 1) are exact and therefore have infinite significant figures. A defined number is one that is arbitrarily chosen (like 6 cm) or one that has been invented (like 60 minutes in an hour). Counted numbers are numbers that are obtained by changing discrete physical objects (like 4 cars in the driveway).
Measured numbers (Category 2) are all numbers that have been measured (like 4.5 mL of water in a graduated cylinder). They are inexact, and therefore, the rules of significant figures must be followed. When measuring a substance, you must record to the digit that varies + or – 1. For example, when using a mass, you would record a substance as 4.25 grams if the scale varied between 4.24 [g], 4.25 [g], and 4.26 …show more content…
This measured quantity has 2 significant digits—the 3 and the 4. The zeros are not significant because they are leading.
B. This measured quantity has 4 significant digits—the 1, 5, and both 0’s. The zeros are significant because they are trailing and there are digits following the decimal point
C. This measured quantity has an ambiguous number of significant figures, because there is not decimal point following the zero. However, we can assume that there are only 2 significant digits—the 1 and 2.
Significant figures must also be taken into consideration while performing calculations with measured numbers. In addition or subtraction problems, the answer must be answered to the same DECIMAL PLACE as the number in the equation with the least specific decimal place. In multiplication and division problems, the answer must have the same number of significant digits as the number in the equation with the fewest significant figures. These considerations must be taken into account so that the answer is no more precise than the measured quantities which the answer is based on. If the equation is multiple steps long, we must be careful not to decrease the number of significant figures while conducting the equation—only at the end when the answer has been