How Are the Atoms in Hydrogen Peroxide Rearranged in This Chemical Reaction

Chemistry IA Chemistry IA—Chemical Reactions - Describing Chemical Change: - in chemical reactions reactants form products - bonds are broken and reformed (matter is REARRANGED) - Reactants → Products - Word Equations—reactants are written (NAME) to the left of the arrow and products (NAME) to the right - Iron + Oxygen → Iron (II) oxide - Hydrogen peroxide → Water + Oxygen - Methane + Oxygen → Carbon dioxide + Water - Chemical Equations—use SYMBOLS and FORMULAS instead of words - Fe(s) + O2(g) → Fe2O3(s) - H2O2(aq) → H2O(l) + O2(g) - CH4(g) + O2(g) → CO2(g) + H2O(l) - s = solid; l = liquid; aq=aqueous solution; g=gas - BALANCING CHEMICAL EQUATIONS: - atoms cannot be created or destroyed, so you MUST make sure that there are the SAME NUMBER of each atom on BOTH SIDES of the equation - *****YOU CANNOT CHANGE SUBSCRIPTS TO BALANCE A CHEMICAL REACTION!!!!***** - Coefficients—small whole numbers placed in front of the chemical formula in order to balance a chemical reaction - 4 Fe(s) + 3 O2(g) → 2 Fe2O3(s) - 2 H2O2(aq) → 2 H2O(l) + O2(g) - CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(l) Chemistry IA - Helpful Hints: 1) Make SURE that you have the correct chemical formula for all reactants and products 2) Begin balancing elements that only appear in ONE formula on either side of the reaction 3) Elements like O may appear in several different compounds on both sides—balance O LAST! 4) Make sure you DOUBLE CHECK all atoms when you are done (balancing one element in a compound will affect all other elements in that compound) 5) Be sure that all COEFFICENTS are in the smallest whole number ratio - Balancing Equations by the ALGEBRAIC METHOD: - useful for difficult equations that are not working by the sight method - CH4 + O2 → CO2 + H2O - STEP 1: Write the given equation with LETTERS for the coefficients a CH4 + b O2 → c CO2 + d H2O - STEP 2: For every type of ATOM, write an algebraic equation using the coefficient letters as variables C: a = c H: 4a = 2d O: 2b = 2c + d - STEP 3: Pick the easiest letter from the equations and assume that letter is equal to 1 assume a = 1 Chemistry IA - STEP 4: Substitute and solve for all the other variables (coefficients) if a=1 then c=1 because a=c and since 4a = 2d, 4(1)=2d so d = 2 then substitute in the equation for O: 2b = 2c + d 2b = 2(1) + 2 2b = 4 b=2 so a=1, b=2, c=1, and d=2 - STEP 5: Replace the letters with the numbered coefficients in the chemical equation CH4 + 2 O2 → CO2 + 2 H2O - STEP 6: Double check to see that it is balanced C → 1 atom on both sides H → 4 atoms on both sides O → 4 atoms on both sides - Types of Chemical Reactions: - although there are many possibilities of combining and reacting compounds, all reactions can be classified into one of 5 basic categories - this allows us to make predictions about what the products will be =? Chemistry IA - 5 types of reactions: 1) Combination (SYNTHESIS) reaction—2 or more simple substances combine to form ONE more complex product - general form: A + X → AX A and X may be elements or simple compounds AX is a compound 2 K(s) + Cl2(g) → 2 KCl(s) H2O(l) + CO2(g) → H2CO3(aq) CaO(s) + H2O(l) → Ca(OH)2(aq) 2) Decomposition reaction—ONE single compound is broken down into 2 or more simpler products - general form: AX → A + X A and X may be elements or simple compounds AX is a compound CaCO3(s) → CaO(s) + CO2(g) H2CO3(aq) → H2O(l) + CO2(g) 2 HgO(s) → 2 Hg(l) + O2(g) 3) Single Replacement reaction—one element replaces another element in a compound - general form: A + BX → AX + B A is a stronger element in the ACTIVITY SERIES B is a weaker element in the ACTIVITIY SERIES AX and BX are compounds Chemistry IA - need to consult the activity series to see if the reaction will occur or not - THE STRONGER ELEMENT ALWAYS ENDS UP IN THE COMPOUND!!!! - Mg(s) + Zn(NO3)2(aq) → Mg(NO3)2(aq) + Zn(s) - Mg(s) + LiNO3(aq) → no reaction - Mg is HIGHER (STRONGER) on the activity series than Zn so it replaces Zn in the compound, BUT Mg is LOWER (WEAKER) than Li so Li STAYS in the compound and that reaction does NOT OCCUR - nonmetals can also replace nonmetals - F2 + 2 NaCl → 2 NaF + Cl2 Chemistry IA 4) Double Replacement reaction—involve an exchange of positive ions between 2 reacting ionic compounds in aqueous solution - general form: AX + BY → - all are ionic compounds - usually occurs in aqueous solution BX + AY - for double replacement reactions, one of the following is usually true: 1) formation of a PRECIPITATE (ionic compound that will NOT dissolve in water) Na2S(aq) + Cd(NO3)2(aq) → CdS(s) + 2 NaNO3(aq) 2) formation of a GAS product that bubbles out of solution 2 NaCN(aq) + H2SO4(aq) → Na2SO4(aq) + 2 HCN(g) 3) formation of a molecular compound (such as water) Ca(OH)2(aq) + 2 HCl(aq) → CaCl2(aq) + 2 H2O(l) 5) Combustion reaction—an element or compound reacts with Oxygen often producing heat and light - general form: A + O2 → AxOy A is an element or compound 2 Mg(s) + O2(g) → 2 MgO(s) S(s) + O2(g) → SO2(g) C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(g) Chemistry IA 5 Types of Reactions: Combination/Synthesis A + X → AX Decomposition AX → A + X Single Replacement A + BX → AX + B Double Replacement AX + BY → AY + BX Combustion A + O2 → AxOy