Chemistry Measurement Notes Chapter 3: Significant Figures, Scientific Notation, Metric Conversions

Measurement Units: Without units, data has no meaning…. Mass = Volume = Length = Temperature= Density= Heat= Without units, data has no meaning….

Uncertainty When reading a measurement from a device, always estimate _________________ This device measures in increments of 1 degree. We know that there is at least 3 degrees, we know there is not more than 4, we have to estimate to the tenths place I’d say 3.8 degrees where _____________________

Accuracy vs. Precision Accuracy- Precision- Example- a substance has a density of 3.00g/mL. In the lab, you find the density to be:

Metric Conversions 3 Metric Prefixes you must know: 1 kilo = 100 centi = 1000 milli = You must also know this: 1 mL= Setting up conversion factors: Convert 45 mm to km Convert 5 m/min to km/hr.

Significant Figures (Sig Figs) All nonzero digits are significant. Ex: Zeros to the right of the decimal are significant, but only if there’s a sig fig before. Zeros to the left of the decimal are NOT significant. Zeros in-between digits are significant.

Sig Figs Continued When adding/subtracting with sig figs, you must report to the least number of decimal places. used. Ex: For multiplying & dividing. Only report to fewest sig figs used.

Scientific Notation Scientific Notation is used to simplify very large or very small numbers. The only digits used in S.N. are ___________ Ex: There can only be __________________________

Calculating with S.N. When you multiply, When you divide, Ex: When you divide, For addition and subtraction,

Celsius to Kelvin

Error & Uncertainty in Measurement Plus/Minus Notation Percent Error