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Basic Units •Length meters •Mass kilograms •Time seconds •Temperature Kelvin •Amount Chm Mole •Current Ampere •Luminous In Candela •Giga (G) •Mega(M) •Kilo(k) •Milli(m) •Micro(m) Metric Prefixes Nano(n) Centi(c) •(G) = 6 •(M) = 10 3 •(k) = 10 -3 •(m) = 10 -6 •(m) = 10 9 10 Metric Prefixes (n) = -9 10 (c) = -2 10 Accuracy •How close you are to the real answer Precision •How well one can repeat his or her work •Repeatability Uncertainty •All measurements have a degree of unreliability •Usually in the last digit of a measurement Burette Measurements Each measurement should have 2 decimals 0 1 2 3 Solve the correct reading for the volume in the burette Burette Measurements Each measurement should have 2 decimals ~ 1.36 0 the last 1 decimal will have 2 uncertainty 3 Significant Digits •Meaningful digits in a number Determining Significance • All non-zero digits • All zeros between non-zero numbers • All trailing zeros if there is a decimal place Multiplication Uncertainty • The answer should have the same number of significant digits as the multiplier with the least number of SD • Same for division Addition Uncertainty • When adding, line up decimal place & add • The decimal places in the answer should = the least • Same for subtraction Scientific Notation •M x •M = 1.00 M < 10.00 •n = an integer n 10 Conversion Factor • Ratio equal to one • 12 inches/1 foot = 1 • Multiply one unit by a CF to obtain another unit w/o affecting magnitude Convert: •2.50 cm to Mm •4.2 ns to ms •3.15 kg to mg Convert: 4.35 kg/L to mg/mL 2.31 mm/ns to cm/Ms Calculate the volume 3 in m occupied by 750 kg of gas with 1.50 g/L 3 1 cm = 1 mL Calculate the mass in kg of a board that has dimensions of 250 mm x 4 4.0 x 10 mm x 2.5 m and had a density of 0.80 g/mL 3 1 ml = 1 cm Calculate the density in g/mL of a 3.14 x 3 10 kg cylinder that 5.0 m long & has a diameter of 2.0 m. How many nm will an object travel in 1/132 ks at 720 miles per hour 1 inch = 2.54 cm 1 mile = 5280 ft Determine the length in miles of a light year • Light year = distance light travels in one year 8 • c = 3.0 x 10 m/s • 1 mile = 5280 ft • 1 inch = 2.54 cm Make the following conversions: • 720 miles per hour to cm/ms 3 • 240 kg/m to mg/nL • 15 Mg to ng