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Numbers in Chemistry Ch. 3 Sect. 2-3 Qualitative vs. Quantitative Write an example of a quantitative observation that you make at home or at school. Metric Base Units Quantity Unit Unit Symbol Length Mass Time meter kilogram second m kg s Temperature Volume Amount of a substance Kelvin Liter K L mole mol Prefixes for Metric Base Units Prefix Symbol Meaning Mega- M million kilo- k thousand deci- d tenth centi- c hundredth milli- m thousandth micro- μ millionth nano- n billionth pico p trillionth Metric Conversions Move decimal to the left M k 1 d cm μ Move decimal to the right n p Dimensional Analysis 1. Write down given measurement. 2. Setup a conversion factor. 3. Cancel units. 4. Calculate answer: 1. Multiply by each number on the top. 2. Divide by each number on the bottom. Scientific Notation Base must be between 1 and 10: 45,000,000,000,000 = 4.5 x 1016 2.641 x 1012 = 2,641,000,000,000 0.00000000000000378 = 3.78 x 10-15 Scientific Notation Calculations Multiply = add exponents Divide = subtract exponents Add/Subtract = convert to same exponent Skills Practice 1 1. 2. 3. 4. 5. 6. 7. 9,434,880 mL 17.8 cases 0.333 cases a) 0.156 m; b)4 x 1010 μg; c) 92,000 μg; d) 91,600 nm a) 2.229 x 107; b) 8.07 x 106; c) 5.41 x 1020; d) 1.12 x 107 a) 2.300021 x 1010; b) 3.5 x 10-9 a) 235,400; b) 0.000000003400