Unit Analysis Compounds one factor

# Unit Analysis Compounds one factor - 23 things = 1 B Molar...

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Unit Analysis Compounds: One factor UNIT ANALYSIS Unit analysis, or dimensional analysis, is a powerful technique for solving general chemistry problems and will be used frequently in OWL questions. In unit analysis, you are essentially multiplying by a ratio that equals "one". Multiplying any number by one does not affect it. "One" can be expressed many ways: (2 / 2) = 1 (x / x) = 1 (12 books / 1 dozen books) = 1 (12.01 grams carbon / 1 mole carbon) = 1 Expressions like the last 2 examples can be used to "convert" a quantity in one set of units, to another. You must include both the number and the units in your "conversion factor". Here are some examples of conversion factors used to solve chemistry problems: A. Avogadro's number = 6.02 x 10 23 things = 1 mole of things This is a number you should learn. You will use it frequently in working chemistry problems. You can write: (6.02 x 10 23 things / 1 mole things) = 1 ... OR . .. (1 mole things / 6.02 x 10

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Unformatted text preview: 23 things) = 1 B. Molar mass Atomic Mass Sulfur (32.06 grams / 1 mole) or (1 mole / 32.06 grams) Molecular Mass CO 2 (44.01 grams / 1 mole) or (1 mole / 44.01 grams) Formula Mass NaCl (58.44 grams / 1 mole) or (1 mole / 58.44 grams) C. Concentration of a solution For a 0.55 molar sodium chloride solution = 0.55 M NaCl, you can write: (0.55 mole NaCl / 1 L solution) or (1 L solution / 0.55 mole NaCl) The ratio you choose depends upon the unit you want to end up in. The unit you want always goes on top (numerator). The unit you are converting from always goes on the bottom (denominator). For example if you want to convert from molecules of CO 2 to moles of CO 2 you would multiply: molecules of CO 2 1 mole CO 2 = moles CO 2 (number) (unit) 6.02 x 10 23 molecules CO 2 (number) (unit) Note that the units molecules CO 2 "cancel out", (molecules CO 2 / molecules CO 2 ) = 1, and you are left in units of moles CO 2 ....
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Unit Analysis Compounds one factor - 23 things = 1 B Molar...

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