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Chem 11: Finish Unit 4 start Unit 5 5-3 Writing Formulas for Ionic Compounds 1. 2. 3. 4. tin (IV) sulphate ammonium sulphate iron (II) sulphate Hg2+ and Cl- forms an ionic compound Common Acids (p74) Memorize the following: acid name HCl hydrochloric acid H3PO4 phosphoric acid HNO3 nitric acid H2SO4 sulfuric acid CH3COOH acetic acid Daily Question Complete the table Cation(C) Anion(A) or Neutral (N) Sr2+ OHNH4+ Ar Monoatomic(M) elements Diatomic (D) Triatomic (T) or Polyatomic (P) Charge The and ! 1) Words for Numbers a “pair” of shoes refers to 2 shoes a “dozen” cats refers to 12 cats a “mole” of particles refers to (insert large number) of molecules 1) Words for Numbers a mole is simply just a word representing a large number 1 mole = 6.022 x 1023 this number is often referred to as “Avogadro’s number” a - voe - ga - dro REMEMBER a mole is just a really really big number! 6.02 x 1023 1 mol = Avogadro’s Number 4 mol = 4 x Avogadro’s Number 0.5784 mol = 0.5784 x Avogadro’s Number we abbreviate mole to mol (similar to kilogram to kg) 0 mol = 0 2) It’s really big… imagine a pea it has a volume of about 0.20 cm3 how many peas would it take….? to fill a fridge to fill a 3 story home 1000 homes 106 1m deep across BC 1018 1m deep on all land 1m deep on entire planet 109 1012 1021 ≈ to a mole this is a large number of particles… REMEMBER just like a 1 equals 12 1 equals 6.022 x 1023 3) Why? why bother with a new unit? what’s easier to say: 3 moles atoms 1.807 x 1024 atoms that’s a pretty good reason 4) Molar Mass atoms and molecules have mass we measure numbers of particles using the mole a mole of atoms will have a mass this mass is called the molar mass 4) Molar Mass molar masses are quoted in units of g/mol g 3.2g 3.2 mol 1mol there are 3.2 grams in every 1 mole of substance 4) Molar Mass here are some molar masses: one mole of…… has a mass of… –oxygen 16.00 g/mol –carbon 12.01 g/mol –helium 4.00 g/mol 4) Molar Mass molecular weight is equivalent to molar mass! the periodic table lists all of the molar masses molar masses in g/mol REMEMBER a represents big number is the number of grams (it’s mass) in a mole of substance Try It if a dozen eggs weighs 15 g, how much does 4 dozen eggs weigh? 15 g = 6.0 x 10 g 4 dozen dozen how much does 4.0 moles of carbon weigh? 12.0 g 4.0 mol mol = 48 g use this “cancellation” method to ensure you are doing it properly! 4) Molecular Mass molecular mass is found by summing the HO molar mass of each atom in a molecule for example - the molar mass of Ca(HCO3)2 2 # atoms x molar mass of atom molecule’s molar mass 5) Calculations a common theme of Chem 11 will be finding mass, moles or molar mass MEMORIZE (and understand) this: mass recall units of molar mass MM moles MM moles mass if you are EVER mass moles MM unsure all you need to do is CHECK the UNITS 5) Calculations for ALL CALCULATIONS I want to see you CANCELLING UNITS! example: how many moles are in 36.0 g of H2O? MM = 18.0 g/mol mass = 36.0 g moles mass MM mol 36.0g 36.0g moles 18.0g 18.0g / mol = 2.00 mol it is a few extra steps, but it is worth it when the answer comes out right! Remember a mole is just a large number of particles consider the following chemical reaction: 2 H2 (g) + O2 (g) 2 H2O (l) you can now describe this as: 2 molecules of hydrogen react with a molecule of oxygen to produce 2 molecules of water or equally well as 2 mol of hydrogen react with 1 mol of oxygen to produce 2 mol of water Try Its find…. mass of 0.034 mol of Li 0.034 mol 6.94 g 0.26g mol # atoms in 4 mol of hydrogen 6.02x1023 atoms 4.0 mol 2.4x1024 atoms mol mass of 0.314 mol of CO2 (12.0 + 2 16.0) g 0.034 mol 13.8g mol # atoms in 4 g helium find moles helium, then convert to atoms