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Classifying Chemical Reactions

Classifying Reactions by what Atoms Do. Combination/SynthesisA Z ?? AZ. A combination reaction is a reaction where two simpler substances are combined into a more complex compound.They are also called synthesis reactions.We will look at 3 combination reactions:the reaction of a metal with oxygenthe reaction of a nonmetal with oxygenthe reaction of a metal and a nonmetal.

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Classifying Chemical Reactions

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    1. We can place chemical reactions into five categories: Combination Reactions Decomposition Reactions Single-Replacement Reactions Double-Replacement Reactions Neutralization Reactions Classifying Chemical Reactions

    2. Classifying Reactions by what Atoms Do Combination/Synthesis A + Z ?? AZ

    3. A combination reaction is a reaction where two simpler substances are combined into a more complex compound. They are also called synthesis reactions. We will look at 3 combination reactions: the reaction of a metal with oxygen the reaction of a nonmetal with oxygen the reaction of a metal and a nonmetal Combination Reactions

    4. When a metal is heated with oxygen gas, a metal oxide is produced. metal + oxygen gas ? metal oxide For example, magnesium metal produces magnesium oxide. Reactions of Metals with Oxygen

    5. Oxygen and a nonmetal react to produce a nonmetal oxide. nonmetal + oxygen gas ? nonmetal oxide Sulfur reacts with oxygen to produce sulfur dioxide gas: S(s) + O2(g) ? SO2(g) Reactions of Nonmetals with Oxygen

    6. Sodium reacts with chlorine gas to produce sodium chloride: 2 Na(s) + Cl2(g) ? 2 NaCl(s) When a main group metal reacts with a nonmetal, the formula of the ionic compound is predictable. If the compound contains a transition metal, the formula is not predictable. Metal + Nonmetal Reactions

    7. Classifying Reactions by what Atoms Do Decomposition AZ ?? A + Z

    8. In a decomposition reaction, a single compound is broken down into simpler substances. Decomposition Reactions

    9. Metal hydrogen carbonates decompose to give a metal carbonate, water, and carbon dioxide. For example, nickel(II) hydrogen carbonate decomposes: Ni(HCO3)2(s) ? NiCO3(s) + H2O(l) + CO2(g) Metal carbonates decompose to give a metal oxide and carbon dioxide gas. For example, calcium carbonate decomposes: CaCO3(s) ? CaO(s) + CO2(g) Carbonate Decompositions

    10. Classifying Reactions by what Atoms Do Single Displacement A + BZ ?? AZ + B

    11. A single-replacement reaction is a a reaction where a more active metal displaces another, less active metal in a compound. Single-Replacement Reactions

    12. When a metal undergoes a replacement reaction, it displaces another metal from a compound or aqueous solution. The metal that displaces the other metal does so because it is more active. The activity of a metal is a measure of its ability to compete in a replacement reaction. In an activity series, a sequence of metals is arranged according to their ability to undergo reaction. Activity Series Concept

    13. Metals that are most reactive appear first in the activity series. Metals that are least reactive appear last in the activity series. The relative activity series is: Li > K > Ba > Sr > Ca > Na > Mg > Al > Mn > Zn > Fe > Cd > Co > Ni > Sn > Pb > (H) > Cu > Ag > Hg > Au Activity Series

    15. A few metals are active enough to react directly with water. These are the active metals. Li, Na, K, Rb, Cs, Ca, Sr, and Ba. They react with water to produce a metal hydroxide and hydrogen gas: 2 Na(s) + 2 H2O(l) ? 2 NaOH(aq) + H2(g) Ca(s) + 2 H2O(l) ? Ca(OH)2(aq) + H2(g) Active Metals

    16. Metal that precede (H) in the activity series react with acids, and those that follow (H) do not react with acids. More active metals react with acid to produce hydrogen gas and an ionic compound: Aqueous Acid Displacements

    17. Cu + AgNO3?

    18. Cr + NiCl2 ?

    19. Cr + Zn(NO3)2 ?

    20. Zn + HCl ?

    21. Fe + HCl ?

    22. Classifying Reactions by what Atoms Do Double displacement AX + BZ ?? AZ + BX Neutralization (special type of double displacement reaction) HX +BOH ?? BX +H2O

    23. These include both precipitation and neutralization reactions. In a double displacement reaction, two ionic compounds in aqueous solution switch anions and produce two new compounds AX + BZ ? AZ + BX If either AZ or BX is an insoluble compound, a precipitate will appear and there is a chemical reaction. If either AZ or BX is water, there is a chemical reaction. If neither precipitate nor water is formed, there is no reaction. Double-Replacement Reactions

    24. Aqueous barium chloride reacts with aqueous potassium chromate: 2 BaCl2(aq) + K2CrO4(aq) ? BaCrO4(s) + 2 KCl(aq) From the solubility rules, BaCrO4 is insoluble, so there is a double-displacement reaction. Aqueous sodium chloride reacts with aqueous lithium nitrate: NaCl(aq) + LiNO3(aq) ? NaNO3(aq) + LiCl(aq) Both NaNO3 and LiCl are soluble, so there is no reaction. Precipitation Reactions

    25. A neutralization reaction is the reaction of an acid and a base. HX + BOH ? BX + HOH A neutralization reaction produces a salt and water. H2SO4(aq) + 2 KOH(aq) ? K2SO4(aq) + 2 H2O(l) Neutralization Reactions

    26. Not all ionic compounds are soluble in water. We can use the solubility rules to predict if a compound will be soluble in water. Solubility Rules

    27. Predicting Reactions Double Displacement

    28. Na2S + ZnCl2 ? Na2S + ZnCl2 ?2 NaCl + ZnS(s)

    29. Mg(NO3)2 + NaOH ? Mg(NO3)2 + 2 NaOH ? Mg(OH)2(s)+ 2 NaNO3

    30. AgNO3 + Na2SO4? AgNO3 + Na2SO4? NR

    31. K2CO3 + HCl ? K2CO3 + 2 HCl ? (H2CO3 + 2 KCl) ?H2O + CO2 + 2 KCl

    32. NH4Cl + KOH ? NH4Cl + KOH ? (NH4OH + KCl) ? NH3 +HOH+ KCl

    33. HNO3 + NaC2H3O2 ? HNO3(aq) + NaC2H3O2(aq) ? HC2H3O2(aq) + NaNO3(aq)

    34. HClO4 + NaOH ? HClO4 + NaOH ? H2O(l) + NaClO4

    35. Critical Thinking: Household Chemicals Many common household items contain familiar chemicals vinegar is a solution of acetic acid drain and oven cleaners contain sodium hydroxide car batteries contain sulfuric acid

    36. There are 4 ways to tell if a chemical reaction has occurred: A gas is detected. A precipitate is formed. A permanent color change is seen. Heat or light is given off. An exothermic reaction gives off heat and an endothermic reaction absorbs heat. Chapter Summary

    37. There are 7 elements that exist as diatomic molecules: H2, N2, O2, F2, Cl2, Br2, and I2 When we balance a chemical equation, the number of each type of atom must be the same on both the product and reactant sides of the equation. We use coefficients in front of compounds to balance chemical reactions. Chapter Summary, continued

    38. There are 5 basic types of chemical reactions. Chapter Summary, continued

    39. In combination reactions, two or more smaller molecules are combined into a more complex molecule. In a decomposition reaction, a molecule breaks apart into two or more simpler molecules. In a single-replacement reaction, a more active metal displaces a less active metal according to the activity series. Chapter Summary, continued

    40. In a double-replacement precipitation reaction, two aqueous solutions produce a precipitate of an insoluble compound. The insoluble compound can be predicted based on the solubility rules. In a double-replacement neutralization reaction, an acid and a base react to produce a salt and water. Chapter Summary, continued

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