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Ch. 10. Chemical Quantities. Measuring Matter. 3 ways to measure the amt. of something: by count, by mass, by volume Apples: (3 for $2.40), ($1.29/lb.), ($12.00/bushel) 1 dozen apples = 12 apples, 2.0 kg apples, or 0.20 bushel apples *S.P. 10.1 pg. 289 on board, P.P. 1-2 on own.
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Ch. 10 Chemical Quantities
Measuring Matter • 3 ways to measure the amt. of something: by count, by mass, by volume • Apples: (3 for $2.40), ($1.29/lb.), ($12.00/bushel) • 1 dozen apples = 12 apples, 2.0 kg apples, or 0.20 bushel apples • *S.P. 10.1 pg. 289 on board, P.P. 1-2 on own
What is a mole? • Mole (mol) = the amt. of a substance that contains 6.02 x 1023(Avogadro’s number) representative particles of that substance • Representative particle = the species present in a substance: usually atoms, molecules, or formula units • 1 mole = 6.02 x 1023 representative particles One day on the Tonight Show, Jay Leno showed a classified add that read: "Do you have mole problems? If so, call Avogadro at 602-1023."
Converting number of particles to moles and vice versa • *S.P. 10.2 pg. 291, P.P. 3-4 • S.P. 10.3 pg. 292, P.P. 5-6
The Mass of a Mole of an Element/Compound • Molar mass = the mass of 1 mole of any substance (= 6.02 x 1023 atoms) • 1 mol Mg = 6.02 x 1023 atoms = 24.3 g • *S.P. 10.4 pg. 296, P.P. 7-8 • *Practice: Find the molar mass of: I2, C, C2H3O2, MgCl2, C6H12O6, Al2(CO3)3 • *10.1 sect. assessment 9-15 pg. 296 Q: How many guacs are in a bowl of guacamole? A: Avocados number.
Mole-Mass Problems • Use the molar mass of an element or compound to convert b/w the mass of a substance and the moles of a substance • Ex: What mass is 3.00 mol of NaCl? • 3.00 mol X 58.5 g/1 mol = 176 g • *S.P. 10.5 pg. 298, p.p. 16-17 • *S.P. 10.6 pg. 299, p.p. 18-19
Mole-Volume Problems • Avogadro’s Hypothesis = equal volumes of gases at the same temp. and pressure contain equal numbers of particles • Temperature and pressure vary w/ each other so to compare moles or # of particles we use STP • Standard Temperature and pressure (STP) = temp. is 0°C and pressure is 101.3 kPa or 1 atmosphere (atm) • At STP, 1 mol or 6.02 x 1023 representative particles, of any gas occupies a volume of 22.4 L. • 22.4 = molar volume of a gas • 1 mol = 22.4 L • *S.P. 10.7 pg. 301, P.P. 20-21
Molar Mass from Density • Molar mass = density at STP x molar volume at STP • Grams/mole = grams/L X 22.4 L/1 mol • *S.P. 10.8 pg. 302, P.P. 22-23 • *10.2 sect. assessment 24-31 pg. 303
Percent Composition • Percent composition = the percent by mass of each element in a compound • The percent by mass of an element in a compound is the number of grams of the element divided by the mass in grams of the compound, multiplied by 100% • K2CrO4– total mass = 194 g K = 40.3% Cr = 26.8% O = 32.9% • *S.P. 10.9 pg. 306, P.P. 32-33 • *S.P. 10.10 pg. 307, P.P. 34-35
Empirical Formulas • Empirical formula = a formula w/ the lowest whole-number ratio of elements in a compound • H2O2 (hydrogen peroxide) empirical formula would be ???, C2H2(acetylene), styrene (C8H8) • 1. Change % automatically to grams • 2. Convert grams to moles using molar mass • 3. Divide each number by the smallest one • 4. Round each to whole number and make formula • *S.P. 10.11 pg. 310, P.P. 36-37
Molecular Formulas • The molecular formula of a compound is either the same as its experimentally determined empirical formula, or it is a simple whole-number multiple of its empirical formula • Divide the molar mass of the molecular formula by the molar mass of the empirical formula. Then multiply the subscripts of the empirical formula by this number. • *S.P. 10.12 pg. 312, P.P. 38-39 • *10.3 sect. assessment pg. 312
National Mole Day6:02am to 6:02pm, October 236.02 x 1023 • Can you believe that some people have never heard of celebrating mole day? • Scientists and students around the world celebrate Mole Day with various activities related to chemistry and/or moles. • Mole Day is celebrated annually on October 23 from 6:02 a.m. to 6:02 p.m. in honor of Avogadro's Number (6.02 x 1023). • How to Celebrate National Mole Day • Send a Mole Day greeting card to friends. • Drink a glass of molasses milk (201g [ 7.1 oz ] of C6H12NNaO3S = 1 mole) at 6:02am & pm. • Bake and eat 6.02 molasses cookies. • Drink 1 mol of H2O (18 g or 0.63oz) of water at 6:02am. • Ask people to guess how many moles you have in a brown paper bag.
What's the mole's favorite college football team?The Florida State SemimolesWhat's the mole's favorite Disney Channel movie?Mole-aweentownWho is the the mole's favorite actor?Mole GibsonWho is the mole's favorite rapper?Mole-ja BoyWhat is the mole's favorite tv show?Mole-eeshaWhy are moles bad at counting?Because they only know one number.What's the mole's favorite brand of soda?Coca-Mola.What's the mole's favorite Disney Movie?The Little MolemaidWhat is the mole's favorite Britney Spears song?Gimme MoleWhy do moles love music from the 60's?Because of Moletown.Why are moles always on the phone?Because they love moleble devices.Why do moles love Tyra Banks?Because she's on America's Next Top MoledelWhy don't moles like Rod Stewart?Because he's a wannabe Barry ManimoleWhat are the moles' favorite line from the Wizard of Oz?"I'm mole-ting, i'm mole-ting."Why don't moles like teenage actresses?Because Lindsay Molehan gives them a bad reputation.Why are moles always eating?Because they're molenourished.
