Chemistry Review Chapter 18 Review Questions Will be EXTRA CREDIT Two Types of Reactions Acid Base reactions Oxidation Reduction reactions Acid Base Reactions Transfer of hydrogen ions protons Makes water into H3O and OH Hydronium and Hydroxide Hydronium Ion Dissolving HCl makes acid Dissolving NH3 makes base Measuring Acid Strength Measure of acidity is pH Concentration of H3O in powers of 10 Negative of that power is the pH pH of pure water is 7 Acids 0 to 7 bases 7 to 14 Use electric current to determine pH Acid Base Reactions Neutralize one another Acid Base Water Salt Generic term salt is the ionic product of an acid base reaction CaCO3 2HCl CO2 H2O CaCl2 Oxidation Reduction Reactions Transfer of electrons Often bonding with oxygen Identifying the components of reaction look for the transfer of electrons Loss of Electrons Oxidation LEO Gain of Electrons Reduction GER LEO the lion goes GER Batteries Batteries function because of an oxidationreduction reaction Anode source of electrons Cathode destination of electrons Need to have a way for electrons to get back to their source Complete the circuit Salt bridge or other device Electric Circuit Electrolysis Electroplating is a useful OxidationReduction Reaction Ancient weak acid electric circuits probably were utilized for this Electrolysis breaks covalent bonds Aluminum oxide ore Water can be source of hydrogen and oxygen For use in a fuel cell Combining the two becomes source of electricity Aluminum from electrolysis Corrosion An oxidation reduction reaction Metals combine with oxygen the oxide product has different properties Weaker Greater volume Rust reduces strength Corrosion An oxidation reduction reaction Metals combine with oxygen Some metals coated or connected by electric circuit with others as a sacrifice metal to protect strength of another Zinc oxidizes more readily than iron Attached to steel ship keels and rudders Zinc galvanized nails Zinc sacrifice metal Combustion Reactions Combustion is an oxidation reduction reaction CH4 2 O2 CO2 2 H2O Methane C and H are oxidized Oxygen is reduced Methane Combustion Periodic Table Groups or Families Alkali Metals Alkaline Earth Metals Transition Metals Oxygen Group chalcogens Halogens Noble Gases Ions of Element Groups Alkali Metals 1 Alkaline Earth Metals 2 Transition Metals number variable Oxygen Group 2 Halogens 1 Noble Gases no ions formed usually Ionic bonds form ionic compounds Need even ratio of charges in the compounds Covalent Bonds When the two atoms are the same electrons within covalent bond shared evenly Nonpolar Polar Covalent Bonds They may be shared unevenly however when the bonded atoms are different Forms a dipole has uneven charge Polar Covalent Bonds Greater electronegativity means greater pulling power on the electrons Greater difference of electronegativity stronger dipole formed in bond High Low Compounds More than one type of atom in the molecule Has a Chemical Formula Sodium Chloride NaCl Ammonia NH3 Subscript tells how many of each Subscript 1 is omitted Chemical Equations C O2 CO2 C s O2 g CO2 g Reactants on left products on right Each are balanced because same number of atoms of reactants as products Letter subscript refers to the phase of the substance Formula Mass Molar Mass Mole A super large number 6 02 1023 used to measure numbers of atoms or molecules a k a Avogadro s number The formula mass of a substance expressed in grams contains one mole Substance Formula Mass Carbon C 12 Oxygen O2 32 Carbon dioxide CO2 44 Sucrose C12H22O11 342 Molar mass of propane C3H8 assume molar mass of C 12 g mole 3 C x 12 g mole 36 g mole assume molar mass of H 1 g mole 8 H x 1 g mole 8 g mole 8 g mole 36 g mole 44 g mole C3H8 Grams calculated from Moles Can find the mass of substance from knowing molar mass and moles Na 23 g mole mole Multiply molar mass times moles 23 g mole x 0 250 moles 5 75 g Mass to moles relationship Proportions Mathematical device to compare ratios Be sure you keep same same in columns and rows g of a moles of a Example g of b or moles of b g of a g of b moles of a moles of b Problem NO O2 NO2 60 grams NO How many grams NO2 produced Balance Equation 2 NO O2 2 NO2 2 NO O2 2 NO2 Problem 60 grams NO How many grams NO2 produced Molar mass of each component NO 30 g mol O2 32 g mol NO2 46 g mol How many moles of NO is 60 g 2 moles Molar ratios 2 1 2 How many moles of NO2 is produced 2 How many grams is that 92 g Problem 192 g O2 g SO2 H 2 S O2 SO2 H 2O Balance first 2 H 2 S 3O2 2SO2 2 H 2O Then determine molar ratios 3 O2 to 2 SO2 3 2 Problem 2 H 2 S 3O2 2SO2 2 H 2O Find molar mass of O2 so you can determine moles of O2 O2 2 O 32 SO2 S 32 2 O 32 H2O 2 H 2 O 16 H2S 2 H 2 S 32 32 g mol O2 64 g mol SO2 18 g mol H2O 34 g mol H2S
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