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Chemical Changes (Reactions) • • • • • • Reactants Products Synthesis Single Replacement Double Replacement Decomposition Chemical Reactions • Indicators – Fizzing (gas produced) – Color change – Gets cloudy/precipitant (solid produced) – Heat released or absorbed – Light emitted – Odor changes Chemical Reactions http://ed.ted.com/lessons/if-molecules-were-people-george-zaidan-and-charles-morton • Reactants Products • H2O2 H2O + O2 –What are the reactants? What are the products? Chemical Reactions There are 4 kinds of Chemical Reactions that occur: Synthesis Decomposition Single Replacement Double Replacement Chemical Reactions • Synthesis –Two or more reactants are combined to form one product. + Chemical Reactions • Decomposition –One reactant breaks down into two or more products. + Chemical Reactions • Single Replacement –An element and a compound combine. –One element from the reactants replaces another in the products. + + Chemical Reactions • Double replacement –Two compounds combine. –Two elements in the reactants switch places in the products. + + Chemical Reactions-Practice Identifying • Example #1 • H2 + O2 H2O Which is it? • Synthesis • Decomposition • Single Replacement • Double Replacement Chemical Reactions • Example #2 • Li3P Li + P Which is it? • Synthesis • Decomposition • Single Replacement • Double Replacement Chemical Reactions • Example #3 Which is it? • Na + MgCl2 Mg + NaCl• Synthesis • Decomposition • Single Replacement • Double Replacement Chemical Reactions • Example #4 Which is it? • SiCl4 + O2 SiO + Cl2 • Synthesis • Decomposition • Single Replacement • Double Replacement Chemical Reactions • Example #5 • C5O3 C + O2 Which is it? • Synthesis • Decomposition • Single Replacement • Double Replacement Chemical Reactions • Example #6 • Rb2O + AlF3 RbF + Al2O3 Which is it? • Synthesis • Decomposition • Single Replacement • Double Replacement Chemical Reactions • Law of conservation of Matter –Atoms are not created or destroyed –The number of atoms at the START of a reaction, there must be the same number of atoms AFTER the reaction. –Equations must be balanced! Chemical Reactions • Balancing Chemical Equations STEPS: –Count the number of atoms for each element in the reactants and in the products. –Compare the numbers to see if each element is balanced (equal) with itself. –Use WHOLE NUMBER coefficients to “fix” unbalanced elements. • Do not change the subscripts! Chemical Reactions • Balancing Chemical Equations STEPS: –Whole number coeficients go in front of the compound or element in the equation and multiply every atom after it. –Ex: NaCl3 has 1 Na atom and 3 Cl atoms but if I needed to have 2 Na atoms in my reactants or products, I would put a coefficient of 2 in front of the compound NaCl3….. 2NaCl3 and now I would have 2 Na atoms, but also 6Cl atoms Chemical Reactions • Example #1 • H2 + O2 H2O • H-2 H-2 • O-2 O-1 • 2H2 + O2 2H2O BALANCED • H-4 H-4 • O-2 O-2 Chemical Reactions • Example #2 • Li3P Li + P • Li-3 Li-1 • P-1 P-1 • Li3P 3Li + P BALANCED • Li-3 Li-3 • P-1 P-1 Chemical Reactions • Example #3 • C5O3 C + O2 • 2C5O3 10C + 3O2 BALANCED Chemical Reactions • Example #4 • Rb2O + AlF3 RbF + Al2O3 Chemical Reactions • Example #5 SnO2 + H2 → Sn + H2O Chemical Reactions • Example #6 • Mg(ClO3)2 + Na NaClO3 + Mg Chemical Reactions • Example #7 • Al2(SO4)3 + RbF AlF3 + Rb2SO4 Chemical Reactions • Identify and Balance • Al + F2 AlF3 Chemical Reactions • Identify and Balance • Ca(MnO4)2 + FeCl4 CaCl2 + Fe(MnO4)4 Chemical Reactions • Identify and Balance • Si3O Si8 + O2 Chemical Reactions • Identify and balance • Cs2O + N2 Cs3N + O2 Warm Up Classify the following chemical reactions as decomposition, single replacement, double replacement or synthesis: For the first equation, what are the reactants and what are the products? Write the chemical formula for Barium Nitride Acids and Bases Draw a Line Like this in the middle of your paper c 0 0 \ 7 14 You will cut out the pictures you get on the paper and arrange them along the pH scale you have drawn. Do your best to guess where things might go…DO NOT glue them down until you check with me firstu Acids properties 1. 2. 3. Conduct electricity (electrolytes) Produce H+ ions Sour taste 4. Corrosive 5. pH values 0-6.9 Acids Acids pH range = 0-6.9 • Examples: Citric Acids, Gastric Acid, Battery Acid, Sodas, tomatoes, etc. • Examples of Formulas: HCl, H2SO4, H3PO4, HNO3, etc SPOILED MILK Bases properties 1. Conduct electricity (electrolytes) 2. OH- ions 3. Bitter taste 4. Corrosive 5. Have a slippery feeling (like soap) 6. pH values 7.1-14 Bases Bases pH range 7.1 to 14 • Examples: Soaps, Cleaning supplies, Hair Relaxers, etc. • Examples of Formulas: NaOH, KOH, Mg(OH)2, Al3(OH), NH3, NH OH Acids & Bases-pH Scale Acids and Bases-Compare & Contrast Acids and Bases--Identify 1. 2. 3. 4. 5. 6. 7. 8. pH =2 HF pH= 7 RbOH Ca(OH)2 pH= 9 Sour taste Slippery feel 9. Electrolyte 10.pH = 13 11.pH = 4 12.H2SO4 13.HBr 14.FrOH 15.Corrosive 16.Bitter taste Acids & Bases • Neutralization Reactions Only an Acid can neutralize a base Only a Base can neutralize an acid • H+ comes off of the Acid and OHcomes off of the Base (OH and H make water!) • Acid + Base Water + Salt Ex: HCl + KOH H2O + KCl Acid/Base Neutralization • HBr + LiOH _________ + _________ • FrOH + HCl _________ + _________ • H2S + Mg(OH)2 ________ + _______ • ______ + HF H20 + KF • ______ + CsOH H20 + CsI