Moles & Mass Dr. Ron Rusay Chem 106

The Mole Definition: The number of carbon atoms in exactly 12 grams of pure 12 C. The number equals 6.02  atoms.Definition: The number of carbon atoms in exactly 12 grams of pure 12 C. The number equals 6.02  atoms.  1 mole = 6.02  units of anything 6.02  “units” of atoms, people, ants, stars, $$$s, etc., etc. = 6.02  “units” of atoms, people, ants, stars, $$$s, etc., etc. = 1 mole There are about 7.4 billion people in the world. How many moles of people are there?

 1 mole = 6.02  units of anything 6.02  people = 6.02  people = 1 mole There are about 7.4 billion people in the world. How many moles of people are there?

Avogadro’s Number Avogadro’s number equals 1 mole ….which equals  “units”  “units” How many molecules are there in one half mole of oxygen?

Calculate the number of atoms of silicon in moles of silicon. What do you need ? Avogadro’s Number 1 mole = 6.02 x atoms What do you get if you divide an avocado into 6.02 x pieces?

Counting by Weighing 12 red 7g each = 84g 12 yellow 4g each=48g 55.85g Fe = x atoms Fe 32.07g S = x atoms S Consult the Periodic Table

CaCO 3 Name? g Oxygen g Copper g Water g Relative Masses of 1 Mole 1 mole of an “ideal” gas equals 22.4 Liters. (A balloon diameter of 35 cm.) What is the volume of 1 mole of water?

Atomic and Molecular Weights Mass Measurements 1 H weighs x g and 16 O x g. 1 H weighs x g and 16 O x g. DEFINITION: mass of 12 C = exactly 12 amu.DEFINITION: mass of 12 C = exactly 12 amu. Using atomic mass units:Using atomic mass units: 1 amu = x g1 amu = x g 1 g = x amu1 g = x amu

Atomic and Molecular Weights Formula Weight a.k.a. Molecular WeightFormula Weight a.k.a. Molecular Weight Formula weights (FW): sum of Atomic Weights (AW) for atoms in formula.Formula weights (FW): sum of Atomic Weights (AW) for atoms in formula. FW (H 2 SO 4 ) = 2AW(H) + AW(S) + 4AW(O)FW (H 2 SO 4 ) = 2AW(H) + AW(S) + 4AW(O) = 2(1.0 amu) + (32.0 amu) + 4(16.0)= 2(1.0 amu) + (32.0 amu) + 4(16.0) = 98.0 amu= 98.0 amu

Atomic and Molecular Weights Molecular weight (MW) is the weight of the molecular formula in amu.Molecular weight (MW) is the weight of the molecular formula in amu. MW of sugar (C 6 H 12 O 6 ) = ?MW of sugar (C 6 H 12 O 6 ) = ? MW = 6(12.0 amu) + 12(1.0 amu) + 6(16.0 amu)MW = 6(12.0 amu) + 12(1.0 amu) + 6(16.0 amu) = 180 amu= 180 amu

Molar Mass A substance’s molar mass is the mass in grams of one mole of the element or compound. (Equals the formula weight: atomic or molecular weight in grams)A substance’s molar mass is the mass in grams of one mole of the element or compound. (Equals the formula weight: atomic or molecular weight in grams) Molar Mass CO 2 = ? C = grams per mole (g/mol) O = grams per mole (g/mol) CO 2 = grams per mole (g/mol) (16.00) = 44.01

Calculate the molar mass of potassium phosphate. What do you need ?

Calculate the mass in grams of 4.00 moles of sulfur. What do you need ?

Percent Composition Mass percent of an element:Mass percent of an element: For iron in (Fe 2 O 3 ), iron (III) oxide = ?For iron in (Fe 2 O 3 ), iron (III) oxide = ? Which iron ore would you buy: one high in Fe 2 O 3 or one high in FeO, Iron (II) oxide?

What do you need ? Molar mass C 10 H 14 N 2 Calculate the percentage composition for all the elements in an alkaloid with the molecular formula C 10 H 14 N 2.

Formulas: Dalton’s Law Dalton’s law of multiple proportions:Dalton’s law of multiple proportions: When two elements form different compounds, the mass ratio of the elements in one compound is related to the mass ratio in the other by a small whole number.

Formulas: Multiple Proportions

Formulas & Multiple Proportions Components of acid rain, SO 2 (g) and SO 3 (g) Compound A contains:Compound A contains: g Sulfur & g Oxygen Compound B contains:Compound B contains: g Sulfur & g Oxygen Mass ratio A: 1 to 1.5; Mass ratio B: 1 to 1Mass ratio A: 1 to 1.5; Mass ratio B: 1 to 1 MUST adjust for atomic mass differences: AW sulfur is 2x the AW oxygen; therefore the oxygen ratios are 2x sulfur.MUST adjust for atomic mass differences: AW sulfur is 2x the AW oxygen; therefore the oxygen ratios are 2x sulfur. S 1 O 3 and S 1 O 2 respectively S 1 O 3 and S 1 O 2 respectively

Compounds with the Same Formula [ eg. C 9 H 8 O 4 ] Aspirin 4-Hydroxyphenylpyruvic acid Dihydroxycinnamic acids: Caffeic acid (3,4-dihydroxycinnamic acid) Umbellic acid (2,4-dihydroxycinnamic acid) 2,3-Dihydroxycinnamic acid 2,5-Dihydroxycinnamic acid 3,5-Dihydroxycinnamic acid

Molar Comparisons of Analgesics Moles : Doses (mol/dose) Which analgesic has the most biologically active ingredient based on moles per dose (mol/dose)? 5.0 g of each would produce the following number of doses: Formula Dosesmol/dose AspirinC 9 H 8 O Ibuprofen C 13 H 18 O 2 25 Naproxen Sodium C 14 H 13 O 3 Na 22.7 Acetaminophen C 8 H 9 NO 2 5

i-clickerQuizQUESTIONS

Strychnine is often the poison of choice in murder mysteries. It has a formula of C 21 H 22 N 2 O 2. How many moles of carbon atoms and oxygen atoms are there in one mole of strychnine?QUESTION A.21 mol of carbon atoms and 1 mol of oxygen atoms B.21 mol of carbon atoms and 2 mol of oxygen atoms C.22 mol of carbon atoms and 21 mol of oxygen atoms D.2 mol of carbon atoms and 2 mol of oxygen atoms

How many atoms of silicon are there in moles of silicon? A) 6.10 x atoms Si B) 2.21 x atoms Si C) 2.21 atoms Si D) 1.64 x atoms SiQUESTION

Potassium phosphate and sodium phosphate is a combination medicine used to make urine more acidic to help prevent kidney stones. What is the molar mass of potassium phosphate? a) 134 g/mol b) g/mol c) g/mol d) g/molQUESTION

Sulfur is derived from the Latin word sulpur. The Greek word for sulfur, θε ῖ ον, which is the source of the international chemical prefix thio-. Sulfur is prominent in volcanic areas like Lassen National Park, which by the way stinks! What is the mass in grams of 4.00 moles of sulfur? A) 128 g B) g C) 12.5 g D) gQUESTION

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QUESTION Morphine, derived from opium plants, relieves pain and is addictive. It’s formula is C 17 H 19 NO 3. What percent, by mass, is the carbon in this compound? A. 42.5% B. 27.9% C. 71.6% D. This cannot be solved until the mass of the sample is given.

Nearly 35 million smokers want to quit each year. Unfortunately, more than 85 percent of those who try to quit relapse, most within a week. Nicotine use is more difficult to withdraw from than heroin. What is the percent composition for nicotine, C 10 H 14 N 2 ? A) 64.14% C, 14.04% H, 21.82% N B) % C, % H, % N C) % C, 8.71 % H, % N D) % C, 3.74 % H, % NQUESTION Nicotiana tobacum