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Catalyst. 1. When balancing equations, you can only change the __________. You cannot change the ______________. 2. Balance the equation: __NO 2 + __H 2 __NH 4 + __O 2 3. Balance the equation: __Al + __Fe 3 N 2 __ AlN + __Fe. Exit Slip Review.
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Catalyst 1. When balancing equations, you can only change the __________. You cannot change the ______________. 2. Balance the equation: __NO2+ __H2 __NH4+ __O2 3. Balance the equation: __Al + __Fe3N2 __AlN+ __Fe
Exit Slip Review 1. In the chemical formula, 6 C2H4, what does the 6 mean? • there are 6 atoms of hydrogen (H) • there are 6 atoms of carbon (C) • there are 6 molecules of dicarbontetrahydride • there are 6 inches of dicarbontetrahydride
Keep in Mind • T-charts don’t really matter! • They are a tool to help you balance the equation • They are not your final answer • You CANNOT put a coefficient in the middle of a compound • If the compound is HgO, which is correct? • 2Hg2O • 2HgO • Hg2O • Only the second one is correct. • So if there are no blanks for you in the problem, you should know where you can put coefficients and where you can’t.
Reducing to Lowest Terms • _2_Zn + _4_HCl _2_ZnCl2+ _2_H2 • Is this balanced?
Keep in Mind • Reduce the coefficients IF YOU CAN • Is this correct? • 4K + 2MgBr2 4KBr + 2Mg • No, this is correct: 2K + MgBr2 2KBr + Mg • Is this correct? • S8 + 12O2 8SO3 • Yes, this is correct • If you see this: …Al (s) + …O2 (g) …Al2O3 (s) • (s) means solid, (g) means gas
PRACTICE 1. N2+ H2 NH3 2. KClO3 KCl + O2 3. NaCl+ F2 NaF + Cl2 4. H2+ O2 H2O 5. Ag2O Ag + O2 6. K + MgBr KBr + Mg 7. NaBr+ CaF2 NaF + CaBr2 8. S8+ O2 SO3 9. H2O + O2 H2O2
Practice, Practice, Practice… Check out this worksheet – you get to select your own “buffet” The questions you complete must add up to 100 points If you do more problems, you will receive extra credit
ChemBalancer • Get the computer that corresponds to your seat number • Log on and open Safari • Google search “chembalancer” • Click on the first link • Click “Start Game” • For this game, you DO have to put 1 as a coefficient. You can’t leave a blank space.
PhET Game • Google “balancing chemical equations game” • Click the first link • Choose your difficulty level!
Exit Slip 1. Balance the following equation: __AgO + __N2 __Ag + __NO3 2. Balance the equation HgO Hg + O2 3. True or false: You can change the subscripts of a chemical equation to balance it. 4. True or false: The balanced equation 4K + 2MgBr2 4KBr + 2Mgis correct because it is reduced to the lowest terms.