Presentation on theme: "The Mole A Counting Unit 09 You WILL NEED your calculators from now on!! Rev 10/12/09."— Presentation transcript:
The Mole A Counting Unit 09 You WILL NEED your calculators from now on!! Rev 10/12/09
Other Counting Units t 1 Dozen =12 things t 1 Pair =2 things t 1 Gross = 144 things (a dozen dozens)
1 mole (mol)= t 602,000,000,000,000,000,000,000 things t = 6.02 x things t What could you possibly measure that is made up of so many things? Yes, we do abbreviate a 4 letter word with a 3 letter word – but not just me – the whole world does!
Random FYI… t If you had a moles worth of rice (meaning 6.02 x grains of rice, it would weigh just as much as if EVERY PERSON on the planet had a MILLION cars!!!!! t So why in the WORLD would we want to work with such a HUGE quantity? Because atoms are so small!!!!
Moles are used to represent very small particles like the number of: t Atoms t Molecules t Formula units Moles enable chemists to count by weighing Now remember our rice story… every person with a million cars… now think about that same amount of hydrogen… guess how much it might weigh… H 2 =2 grams!
1 mole of an atom = t Its mass on periodic table t For example: 1 mole Carbon = grams 1 mol C = ? Atoms C t grams of Carbon = ? atoms 6.02 x10 23 atoms Reminder: 1 ATOM of C weighs amus.
What is the molar mass? t Copper (Cu) 63.55g = 1 mol Cu t Oxygen (O 2 ) 16.00g per mol of O…but… 32.00g = 1 mol O 2 The mass of the mole, silly!
What is the molar mass? t Copper II Oxide (CuO) (Whats the roman numeral mean? Why II?) 63.55g /mol Cu g /mol O 79.55g /mol CuO t You try Ammonium nitrate, NH 4 NO 3 2(14.0) g/ mol N 4( 1.0) g/ mol H + 3 (16.0) g/ mol O 80g/mol
Dimensional Analysis t Conversion factors can be used to convert units t g = 1 mol C t 3.85 mol C would have a mass of what? 3.85 mol C (1 mol C) (12.01g C) = 46.2 g C
t 3.2 mol of malachite,Cu 2 CO 3 (OH) 2 is how many grams? t 1 mol= g 3.2 mol t Practice WB pp (1 mol malachite ) (221.13g malachite ) = 708 g Malachite
Mole Ratios in Balanced Equations t Coefficients represent mole ratios 2CuOCO 2 2CuO + C --> 2Cu + CO 2 t 2 mol CuO / 1 mol CO 2 t How many moles of CuO is needed to produce 8 moles of CO 2 ? t 8 mol CO 2 Note: BOTH units cancel! (1 mol CO 2 ) (2 mol CuO) = 16 mol CuO
To Do: sugarful Bring a piece of sugarful gum in the wrapper tomorrow.
t Balanced 4NH 3 + 7O 2 --> 4NO 2 + 6H 2 O t How many moles of oxygen are needed to react with 200 moles of ammonia (NH 3 ) 200mol NH 3 (7mol O 2 ) (4 mol NH 3 ) = 350mol O 2 t How many grams of O 2 is that equal to? 350 mol O 2 (1 mol O 2 ) (32 g O 2 ) = 11,200 g O 2
1 mol = 6.02 x I AM FU. 1 mole NaCl = 6.02 x formula units of NaCl onsons tomstoms oleculesolecules ormulaormula nitsnits 1 mole NH 4 + = 6.02 x ions NH 4 +1 mole NH 4 + = 6.02 x ions NH mole Au = 6.02 x atoms Au 1 mole CO 2 = 6.02 x molecules CO 2 mole equalsmass on periodic table1 mole equals formula mass on periodic table different substances coefficients in balanced equationsMole to mole ratios of different substances are the coefficients in balanced equations REVIEW Coefficients in balanced equations are NOT gram to gram ratios, must first convert to moles to use molar ratio
Practice: Calculate Reactant mass & Product mass NH 3 + O 2 --> NO 2 + H 2 O t 17g 32g 46g18g t 49g 64g So what do we need to do? Balance the equation t 4NH 3 + 7O 2 --> 4NO 2 + 6H 2 O t 68 g 224g184g108g t 292g = 292g