Steps to find grams in chemical reaction Reactions continued And chemical review Balance the equation to get molar ratios Find molar mass of the substances in question Find moles of the one given in grams Set up a proportion to compare molar ratio to the moles of known and unknown If the unknown is on top it is easier to solve so set it up that way Proportions Mathematical device to compare ratios Cross multiply to solve Correctly organized Be sure you keep same same in columns and rows Mass to moles relationship Proportions Proportions to find moles Correctly organized Example moles of a coefficien t of a moles of b coefficien t of b or moles of a moles of b coefficien t of a coefficien t of b Correctly organized It doesn t matter how you write the first ratio as long as you label the numbers Try to put unknown on the top easier to solve The second ratio needs to match the first cross multiply to solve The convert moles back to grams Problem NO O2 NO2 Problem 2 NO O2 2 NO2 64 grams O2 How many grams NO2 produced 64 grams O2 How many grams NO2 produced First Balance Equation Balance Equation Determine molar ratios of them 1 2 Find molar mass of each component NO2 46 g O2 32 g NO 30 g 2 NO O2 2 NO2 Problem 2 NO O2 2 NO2 64 grams O2 How many grams NO2 produced Molar mass of each O2 32 g NO2 46 g How many moles is 64 grams O2 2 moles 1 Problem 2 NO O2 2 NO2 64 grams O2 How many grams NO2 produced Molar mass of each O2 32 g NO2 46 g Molar ratios O2 NO2 is 1 2 Two moles of O2 do you need proportion to find moles of NO2 So four moles of NO2 is produced How many grams is that 4 mol x 46 g mol 184 grams Problem 32 grams SO2 How many grams O2 used 2 H 2 S 3O2 2SO2 2 H 2O Find molar masses SO2 32 32 O2 2x1 16 H2O 2x1 16 H2S 2x1 32 Set up proportion 64 g mol SO2 32 g mol O2 18 g mol H2O 34 g mol H2S 32 grams SO2 How many grams O2 used with the unknown on top the O2 moles O2 Problem H 2 S O2 SO2 H 2O 32 grams SO2 How many grams O2 used Problem 32 grams SO2 How many grams O2 used H 2 S O2 SO2 H 2O Balance first 2 H 2 S 3O2 2SO2 2 H 2O Then determine molar ratios 2 SO2 to 3 O2 Problem 32 grams SO2 How many grams O2 used 2 H 2 S 3O2 2SO2 2 H 2O 32 g SO2 needs how many grams O2 How many moles is 32 g SO2 32 g SO 2 1 mole 0 5 moles SO 2 64 g Problem 2 H 2 S 3O2 2SO2 2 H 2O How many moles O2 is needed 0 5 moles SO2 in 2 3 ratio with O2 0 75 moles O2 32 g SO 2 Problem 6 C O2 CO2 Is it balanced Molar ratio 1 1 1 4 grams oxygen Grams carbon consumed Grams carbon dioxide produced 32 grams SO2 How many grams O2 used 1 mole 0 5 moles SO 2 64 g Problem 6 C O2 CO2 Molar ratio 1 1 1 4 grams oxygen 1 mole O2 32 g 4 g O2 1 mole 0 125 moles O2 32 g 2 Problem 6 C O2 CO2 Molar ratio 1 1 1 0 125 moles O2 in 1 1 ratio 0 125 moles C 0 125 moles CO2 Reaction of ozone to oxygen C O2 CO2 Problem 6 0 125 moles C Grams carbon consumed 0 125moles C 12 g 1 5 g C 1 mole 0 125 mole CO2 Acid Base Reactions Collision of molecules required for it to occur Increase concentration Increase temperature Catalyst can facilitate reaction 44 g 5 5 g CO2 1 mole Energy of reactions Release heat energy from chemical bonds EXOTHERMIC Methane combustion Chlorine catalyst Reaction Speed Two Types of Reactions Acid Base reactions Oxidation Reduction reactions Take heat energy into chemical bonds ENDOTHERMIC Formation of water Hydronium Ion Dissolving HCl makes acid Transfer of hydrogen ions protons Makes water into H3O and OH Hydronium and Hydroxide 3 Dissolving NH3 makes base Measuring Acid Strength Measure of acidity is pH Neutralize one another Acid Base Water Salt Generic term salt is the ionic product of an acid base reaction Use electric current to determine pH CaCO3 2HCl CO2 H2O CaCl2 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 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 Electrolysis Electroplating is a useful OxidationReduction Reaction Ancient weak acid electric circuits probably were utilized for this Electrolysis breaks covalent bonds Acid Base Reactions Batteries Electric Circuit 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 Aluminum from electrolysis Corrosion An oxidation reduction reaction Metals combine with oxygen the oxide product has different properties Weaker Greater volume Aluminum oxide ore Water can be source of hydrogen and oxygen For use in a fuel cell Combining the two becomes source of electricity 4 Rust reduces strength Corrosion Zinc sacrifice metal 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 Combustion Reactions Methane Combustion Periodic Table Ions of Element Groups Covalent Bonds Combustion is an oxidation reduction reaction CH4 2 O2 CO2 2 H2O Methane C and H are oxidized Oxygen is reduced Groups or Families Alkali Metals Alkaline Earth Metals Transition Metals Oxygen Group chalcogens Halogens Noble Gases 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 When the two atoms are the same electrons within covalent bond shared evenly Nonpolar 5 Polar Covalent Bonds They may be shared unevenly however when the bonded atoms are different Forms a dipole has uneven charge 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 Substance The formula mass of a substance expressed in grams contains one mole Formula Mass Carbon C 12 Oxygen O2 32 Carbon dioxide CO2 44 Sucrose C12H22O11 342 Mass to moles relationship Compounds More than one type of atom in the molecule Has …
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