Scientific measurement Scientific notation, sig figs, metric system

Measurements Quantity containing both numbers and a unit

Scientific Notation A coefficient and 10 raised to a power Always written with number in ones place 602,000,000,000,000,000,000,000 = 6.02 x 1023 1,536 = 1.536 x 103 0.0007985 = 7.985 x 10-4

Practice Write the following in scientific notation: 89,000,000 0.001480 4,251,000,000 0.000000853 Write the following in decimal form: 2.35 x 10-9 4.771 x 105 2.00 x 103

Accuracy vs. precision How close to actual value How close a series of measurements are to one another

Illustration Draw an example for precision and accuracy

Used to determine accuracy Error = experimental value – actual value % error = (absolute value of error)/(actual value) x 100 Used to determine accuracy

Significant figures All of the digits that are known, plus a last digit that is estimated Rules for adding/subtracting Rules for multiplying/dividing Rounding A calculated answer cannot be more precise than the least precise measurement from which it was calculated. When taking a measurement, you can estimate to 1/10 of the smallest division.

International system of units (SI) Metric system Meter, kilogram, kelvin, second and mole Temperature: measure of how hot or cold an object is. Dependent of direction of heat transfer Kelvin or degree Celsius Kelvin: 273.15 K is freezing, 373.15 K is boiling (water) Celsius: 0 is freezing and 100 is boiling (water) Absolute zero is 0K or -273.15 degrees Celsius

Vocabulary Energy: ability to do work or produce heat Joule or calorie Density= mass/volume Dependent on composition of matter, not size of sample Dimensional analysis: way to analyze and solve problems using units, or dimension, of the measurement Conversion factor: ratio of equivalent measurements

Examples What are common conversion factors that you use?