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Starter. How would you record the following measurements? How many sig figs? a. b. Count the sig figs in the following measured values: a. 0.0004050 b. 1890 c. 1890.090 d. 6.930 x 10 6. mL. inches. Starter Answers.

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  1. Starter • How would you record the following measurements? How many sig figs? • a. b. • Count the sig figs in the following measured values: • a. 0.0004050 • b. 1890 • c. 1890.090 • d. 6.930 x 106 mL inches

  2. Starter Answers • How would you record the following measurements? How many sig figs? • a. b. • Count the sig figs in the following measured values: • a. 0.0004050 4 sig figs • b. 1890 3 sig figs • c. 1890.090 7 sig figs • d. 6.930 x 106 4 sig figs mL 4.98mL 3 sig figs 8.24 in 3 sig figs inches Your last digit might be different!

  3. Arithmetic with Significant Figures    

  4. Arithmetic with sig figs! Sometimes we need to use our measured values in calculations. Here are some examples:

  5. Arithmetic with sig figs! When you do arithmetic, you need to figure out how many sig figs your answer should have. This will depend on the sig figs in your measurements. Remember, your measurements might have been made with different amounts of precision. This is reflected by the number of sig figs. Low precision in one measurement will limit the precision of your answer.

  6. Example Let’s say you wanted to calculate the density of a liquid. To do this, you found the volume using a beaker. The volume was 55 mL. Then, you used an analytical balance to measure the mass. The mass was 55.1345 g. 6 sig figs 1.0 g/mL 2 sig figs 2 sig figs How precise is the answer? How many sig figs should I record?

  7. Multiplication and Division The general rule for multiplication and division is that your answer must have only as many sig figs as the least precise measurement. Example 2 sig figs 3 sig figs 13 m3 4 sig figs Round to 2 sig figs

  8. More Example

  9. More Example 4 sig figs 3 sig figs 3 sig figs 1 sig fig 3 sig figs 2 sig figs 2 sig figs 1 sig fig 2 sig figs 5 sig figs 2 sig figs

  10. Addition and Subtraction The rules for addition and subtraction are different. For addition and subtraction the answer must be rounded to the least number of decimal places from any of the terms. 2 decimal places 5.9 mL 1 decimal place Round to 1 decimal place

  11. Examples

  12. Answers 2 decimal places 3 decimal places 2 decimal places 0 decimal places 1 decimal place 0 decimal places 2 decimal places 1 decimal place 1 decimal place 3 decimal places 2 decimal places 2 decimal places

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