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Double-Replacement Reactions. What will I see? …Predicting Products. Double-Replacement Reactions. when 2 aqueous ionic compounds exchange ions AX + BY AY + BX What are the metals? What are the nonmetals?. A & B. X & Y. Steps for predicting products:.
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Double-Replacement Reactions • What will I see? …Predicting Products
Double-Replacement Reactions • when 2 aqueous ionic compounds exchange ions AX + BY AY + BX • What are the metals? • What are the nonmetals? A & B X & Y
Steps for predicting products: • Write the components of the reactants in a skeleton equation Al(NO3)3 + H2SO4 • Identify the cations & anions in each compound Al(NO3)3 has Al+3 and NO3- H2SO4 has H+ and SO4-2 • Pair up each cation with the anion from the other compound Al+3 pairs with SO4-2 H+ pairs with NO3-
Steps for predicting products: • Write the formulas for the products using the pairs from previous step • Write the complete equation for the double-replacement reaction • Balance the equation (SO4)3 Al+3 SO4-2 Al2 HNO3 H+ NO3- 2 Al(NO3)3 + H2SO4 3 Al2 (SO4)3 + 6 HNO3
Let’s practice… • Aqueous lithium iodide and aqueous copper (II) nitrate react to produce what? • What is the formula for lithium iodide & copper (II) nitrate? Li+ I- LiI Cu+2 NO3- Cu(NO3)2
Steps for predicting products: • Write the components of the reactants in a skeleton equation LiI + Cu(NO3)2 • Identify the cations & anions in each compound LiI has Li+ and I- Cu(NO3)2 has Cu+2 and NO3- • Pair up each cation with the anion from the other compound Li+ pairs with NO3- Cu+2 pairs with I-
LiI + Cu(NO3)2 LiNO3 + CuI2 Steps for predicting products: • Write the formulas for the products using the pairs from previous step • Write the complete equation for the double-replacement reaction • Balance the equation NO3 Li+ NO3- Li I2 Cu+2 I- Cu 2 2
Will the products be soluble or precipitate out? • Look at the solubility table on the back of your periodic table • For each compound formed: 1. first look up the anion on the table 2. select the cation category 3. if the compound formed is insoluble it will precipitate: label (s) after the formula 4. if soluble label (aq) after the formula
Solubility Rules 1. Compounds containing Group I ions and ammonium are soluble. 2. Nitrates, acetates and chlorates are soluble. 3. Chlorides, bromides and iodides are soluble except with lead, silver, copper(II), and mercury ions. Fluorides are soluble except with Group II and lead ions. 4. Sulfates are soluble except those containing barium, strontium, calcium, lead and silver ions. 5. Carbonates, chromates, phosphates, hydroxides are insoluble except with those cations in rule 1. 6. Sulfides are insoluble except for calcium, barium, strontium, magnesium, sodium, potassium, and ammonium ions.
What will you see? For the first product: • What is the anion in LiNO3? NO3- nitrate What is the cation? Li+ lithium • Is the anion/cation combination soluble or insoluble? soluble = (aq)
What will you see? For the second product: • What is the anion in CuI2? What is the cation? • Is the anion/cation combination soluble or insoluble? I- iodide Cu+2 copper (II) not soluble = (s)
2 LiI + Cu(NO3)2 2 LiNO3 + CuI2 Write the balanced equation with descriptors: (s) (l) (g) or (aq) • Reminder: All reactants are aqueous. (aq) (aq) (aq) (s) That’s all folks!