DIMENSIONAL ANALYSIS (also known as Factor-Label Method)
Read problem Identify data Make a unit plan from the initial unit to the desired unit Change initial unit to desired unit Cancel units and check Do math on calculator
Conversions If you know ONE conversion for each type of measurement, you can convert anything!You must memorize and be able to use the metric conversions:
Conversion Factors Fractions in which the numerator and denominator are EQUAL quantities expressed in different units Example: 1 ft = 12 in. Factors: 1 ft. and 12 in 12 in 1 ft. Example: 1 g = 102 cg. Factors: 1 g. and 102 cg 102 cg 1 g
How many minutes are in 2.5 hours? Conversion factor 2.5 hr x 60 min = 150 min 1 hr
Sample Problem You have $7.25 in your pocket in quarters. How many quarters do you have?7.25 dollars 4 quarters 1 dollar
You have 200 L of gasoline in your car. How many milliliters do you have?200 liters 103 milliliters 1 liter
Learning Check SET UP THESE PROBLEMS USING DA - 2.22 cg = _______g 1.7 x 106 ng = ___________ g .288 g = __________mg 1.5 KL = ___________L
Multi-Step Problems You are in Paris and want some peaches for lunch. The sign in the fruit stand indicates that peaches are 11.5 francs per kilogram. Given that there are approximately 5 francs to the dollar, calculate what a pound of peaches will cost in dollars.
Practice Problems Mrs. Borden has 3 classes of Chemistry. Each class has 25 students in it and they are each required to pay $15.00 for their lab fee. How much money will she have at the end of the semester if everyone pays their fee?Students in chemistry are required to write 10 lab reports per year. Each lab report has 6 sections each. Mrs. Borden requires that each section consists of a paragraph with no less than 7 sentences. How many paragraphs will each student write in 1 year time?
Complex Units
YOU TRY IT The density of gold is 19.3 g/mL. What is gold’s density in decigrams per liter?
NEW UNITS These are units you have never used but you must know for the rest of the year.1 mole of any element or compound = its mass1 mole of any element or compound = 6.02 x 1023 representative particles
CONVERSION FACTORS How to calculate mass, using the periodic table: Na = 23.0 g and Cl = 35.5 g 23.0+ 35.5 therefore 1 mole of NaCl = 58.5 g 58.5 g
Practice pROBLEM You are given 3.5 moles of NaCl, how many grams of NaCl do you have?
CONVERSION FACTORS Nothing to calculate, the number of particles is the same for every element therefore 1 mole of NaCl = 6.02 x 1023 Particles or 1 mole of NaCl 6.20 x 1023 particles
Practice pROBLEM You are given 3.5 moles of NaCl, how many particles of NaCl do you have?
Multi-Step Problems
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