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Polyatomic Ions
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-ate and -ite NO3- nitrate NO2- nitrite
-ate is great, -ite is slight -ate has one more oxygen than –ite hypo- under one less per- completely one more
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Name other ions by analogy with element above
SeO42- selenate BrO3- bromate HSe- hydrogen selenide H2AsO4- dihydrogen arsenate
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Permanganate is? MnO2- MgO4- MnO42- MnO4- 130 4
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IO- is? hypoiodite iodite iodide iodate iodine monoxide 130 9
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Hydrogen selenite is? H2Se H2SeO3 HSeO3- HSeO2- HSeO4- 130 10
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Names of Ionic Compounds
1. Name the metal first. For all metals except groups 1,2, Ag, Zn, Al use Roman numerals in parentheses for charge. 2. Then name the polyatomic ion or non-metal, changing the ending of the non-metal to -ide. 3. For hydrates use Greek prefixes to specify the number of water molecules e.g. dihydrate
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Some Common Hydrated Ionic Compounds
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Simple Salts Ti3N4 titanium(IV) nitride Fe2O3 iron(III) oxide Ag2O
silver oxide SnCl4.5H2O tin(IV) chloride pentahydrate Mg3N2 magnesium nitride ZnI2 zinc iodide No roman numerals needed for Ag, Zn, Al Using roman numerals is only wrong for groups 1 and 2
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Salts with Polyatomic Ions
NH4NO3 ammonium nitrate KBrO3 potassium bromate Mg(MnO4)2.6H2O magnesium permanganate hexahydrate Cu(OH)2 copper(II) hydroxide
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Iron(II) phosphate is? Fe2PO4 FePO3 Fe3(PO4)2 Fe2(PO4)3 Fe(PO4)2 130
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Zinc iodate is? ZnIO4 ZnIO3 Zn(IO4)2 Zn(IO3)2 ZnI2 10 130
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Naming Acids Non-oxy acids hydro___ic acid Oxy acids -ate __ic acid
-ite __ous acid Always in aqueous solution HCN (aq) hydrocyanic acid H2TeO4 (aq) telluric acid HBrO2 (aq) bromous acid HCN hydrogen cyanide
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Hydrosulfuric acid is H2SO4 (aq) H2SO3 (aq) H2OS (aq) HSO4- (aq)
H2S (aq) 9 130
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Which substance is named correctly?
ZnCl2 zinc chloride SCl2 sulfur chloride FeCl2 iron chloride HCl (aq) hydrogen chloride HClO3 (aq) hydrochloric acid 10 130
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Properties of Molecular & Ionic Compounds
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Electrical Conductivity Ionic Solution
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Molar Mass Sum atomic masses represented by formula
atomic masses in amu molecular mass in amu element molar masses in g/mol compound molar mass in g/mol Numerical values are the same
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Percentage Composition
Chemical formula gives the relative proportions by atom or mole Percentage composition gives the relative proportions by g (out of 100 g total)
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EXAMPLE: What is the percent composition of chloroform, CHCl3, a substance once used as an anesthetic? Molecular mass = ( )amu = amu 1(12.011) %C = 100% = % C 1( ) %H = 100 = 0.844% H 3(35.453) %Cl = 100 = % Cl
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EXAMPLE: What is the percent composition of chloroform, CHCl3, a substance once used as an anesthetic? %C = % C %H = 0.844% H %Cl = % Cl Total = =
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Simplest (Empirical) Formula
Simplest integer ratio of the atoms in a compound Assume 100 g of compound, %element is then g element in sample g element x 1 mol element = mol element g element CHCl g C x 1 mol C = mol C g C Determine simplest integer mole ratio
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EXAMPLE: Phosphorus burns in air to produce a white compound that is 43.7% P and 56.3% O by mass. What is the empirical formula of the compound? Assume 100 g of compound Relative Number of Atoms Multiply by Integer mass 43.7g P 56.3g O (mass/atomic mass) Divide by Smaller 43.7/ = 1.41 56.3/ = 3.52 2 1.00 2 2 2.50 5 1.41/1.41 = 1.00 3.52/1.41 = 2.50 .25, .33, .5, .67, .75 ¼, ⅓, ½, ⅔, ¾ 1:1.25 = 4:5 Empirical Formula P2O5
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Molecular Formula The exact proportions of the elements that are contained in a molecule An integer multiple (X) of the empirical formula
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Molecular Formula from Simplest Formula
empirical formula mass FM sum of the atomic weights represented by the empirical formula molar mass = MM = X FM
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Molecular Formula from Simplest Formula
first, knowing MM and FM X = MM/FM then MF = X EF
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EXAMPLE: Our phosphorus compound has a molar mass of ~285
EXAMPLE: Our phosphorus compound has a molar mass of ~285. What is the molecular formula? FM = 2 x x = MM X = = = 2 FM thus MF = 2 EF P4O10
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The empirical formula of a substance is found to be CH3O and its molecular weight is found to be roughly 61 g/mol. What is the true molecular weight of the substance? 30.5 g/mol 31.0 g/mol 61.0 g/mol 62.0 g/mol 124.0 g/mol 130 52
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