Types of Chemical Reactions

Review A chemical equation describes a chemical change. The Law of Conservation of Mass says that the number and kind of atoms going INTO a chemical reaction must be the same as the number and kind of atoms coming OUT. Balancing an equation makes it obey the Law of Conservation of Mass.

The six types of chemical reactions we will discuss are: Synthesis Decomposition Single Displacement Double Displacement Acid-Base Combustion Types of Reactions

Two or more substances combine to form one substance. The general form is A + X  AX Example: 2Mg + O 2  2MgO Synthesis Reactions

Decomposition Reactions One molecule breaks down to form two or more substances. The general form is AX  A + X Example: 2H 2 O  2H 2 + O 2

Single Displacement Reactions A single element switches places with another element in a chemical compound. The general form is A + BX  AX + B Example: Ni + 2AgNO 3  2Ag + Ni(NO 3 ) 2

Example: Ni + 2AgNO 3  2Ag + Ni(NO 3 ) 2 Single Displacement Reactions Ni + 2AgNO 3  Nickel replaces the metallic ion Ag +. The silver becomes free silver and the nickel becomes the nickel(II) ion.

Double Displacement Reactions The cations of two compounds exchange places with each other. The general form is: AX + BY  AY + BX

Double Displacement Example: NaOH + CuSO 4  The Na + and Cu 2+ switch places. Na + combines with SO 4 2- to form Na 2 SO 4. Cu 2+ combines with OH - to form Cu(OH) 2 2NaOH + CuSO 4  Na 2 SO 4 + Cu(OH) 2

Acid-Base Acid-base reactions are double displacement reactions which takes place when an acid and base react with each other. HA + BOH → H 2 O + BA Acid Base Example: HBr + NaOH → NaBr + H 2 O The H + ion in the acid reacts with the OH - ion in the base, causing the formation of an ionic salt (NaBr) and water.

Combustion Reaction When a compound containing carbon and hydrogen combines with oxygen, the products formed are heat, water, and carbon dioxide. CH 4 + 2O 2  CO 2 + 2H 2 O

1)Does the reaction look like this: X + O 2  CO 2 + H 2 O ? If yes - combustion reaction. 2) Is there only one product? If yes - synthesis reaction. 3) Is there only one reactant? If yes - decomposition reaction. 4) Are any reactants only one kind of element? If yes - single displacement reaction. 5) Is water a product of this reaction? If yes - acid base reaction. If not - double displacement reaction.

Learning Check... Classify each of the following reactions: H 2 + Cl 2  2HCl Synthesis Ca + 2H 2 O  Ca(OH) 2 + H 2 Single displacement

Classify each of the following reactions: 2CO + O 2  2CO 2 Synthesis 2KClO 3  2KCl + 3O 2 Decomposition Learning Check...

Classify each of the following reactions: CH 3 SH + 3O 2  CO 2 + 2H 2 O + SO 2 Combustion Zn + 2HCl  ZnCl 2 + H 2 Single displacement Learning Check...

Predicting the Outcomes of Chemical Reactions Predicting Single Displacement Outcomes Predicting Single Displacement Outcomes Need activity series handout. Need activity series handout. Any metal on the activity series is capable of displacing any metal ion below it. Any metal on the activity series is capable of displacing any metal ion below it. Metals cannot displace more active metals. Metals cannot displace more active metals. If a metal is placed in contact with a compound that has a more active metal, no reaction will occur. If a metal is placed in contact with a compound that has a more active metal, no reaction will occur. A halogen can displace any halogen beneath it. A halogen can displace any halogen beneath it. Example: Cl 2 can displace Br -1 ions and I -1 ions from compounds, but it cannot displace F -1 ions. Example: Cl 2 can displace Br -1 ions and I -1 ions from compounds, but it cannot displace F -1 ions.

Predicting the Outcomes of Chemical Reactions Predict whether a chem. rxn will occur in each of the following cases, and if it does, what products it will form. Predict whether a chem. rxn will occur in each of the following cases, and if it does, what products it will form. Mg + Cu(NO 3 ) 2  ??? Mg + Cu(NO 3 ) 2  ??? Mg is higher than Cu on the activity series. Mg is higher than Cu on the activity series. Mg will displace Cu from Cu(NO 3 ) 2. Mg will displace Cu from Cu(NO 3 ) 2. The expected products are Mg(NO 3 ) 2 and Cu. The expected products are Mg(NO 3 ) 2 and Cu. Mg + Cu(NO 3 ) 2  Mg(NO 3 ) 2 + Cu Mg + Cu(NO 3 ) 2  Mg(NO 3 ) 2 + Cu Fe + AlCl 3  ??? Fe + AlCl 3  ??? Fe is lower than Al on the activity series. Fe is lower than Al on the activity series. There will be no chemical reaction. There will be no chemical reaction.

Predicting the Outcomes of Chemical Reactions Would you expect each of the following chemical reactions to occur as written? Would you expect each of the following chemical reactions to occur as written? Li + NaCl  LiCl + Na Li + NaCl  LiCl + Na 2Al + 3CuCl 2  2AlCl 3 + 3Cu 2Al + 3CuCl 2  2AlCl 3 + 3Cu Ni + Zn(NO 3 ) 2  Ni(NO 3 ) 2 + Zn Ni + Zn(NO 3 ) 2  Ni(NO 3 ) 2 + Zn Mg + 2HBr  MgBr 2 + H 2 Mg + 2HBr  MgBr 2 + H 2 F 2 + 2KBr  2KF + Br 2 F 2 + 2KBr  2KF + Br 2 I 2 + 2KBr  2KI + Br 2 I 2 + 2KBr  2KI + Br 2

Predicting the Outcomes of Chemical Reactions Predicting Double Displacement Outcomes Predicting Double Displacement Outcomes Need solubility rules handout. Need solubility rules handout. A dbl displacement reaction will occur if at least one of its products is insoluble. A dbl displacement reaction will occur if at least one of its products is insoluble.

Predicting the Outcomes of Chemical Reactions Predict whether a chem. rxn will occur in each of the following cases, and if it does, what products it will form. Predict whether a chem. rxn will occur in each of the following cases, and if it does, what products it will form. NaOH + Cu(NO 3 ) 2  ??? NaOH + Cu(NO 3 ) 2  ??? Two possible products: NaNO 3 and Cu(OH) 2 Two possible products: NaNO 3 and Cu(OH) 2 NaNO 3 is soluble, but Cu(OH) 2 is not. NaNO 3 is soluble, but Cu(OH) 2 is not. This reaction will proceed. This reaction will proceed. KCl + Fe(NO 3 ) 3  ??? KCl + Fe(NO 3 ) 3  ??? Two possible products: KNO 3 and FeCl 3 Two possible products: KNO 3 and FeCl 3 KNO 3 and FeCl 3 are both soluble. KNO 3 and FeCl 3 are both soluble. There will be no chemical reaction. There will be no chemical reaction.

Predicting the Outcomes of Chemical Reactions Would you expect each of the following chemical reactions to occur as written? Would you expect each of the following chemical reactions to occur as written? BaCl 2 + (NH 4 ) 2 SO 4  BaSO 4 + 2NH 4 Cl BaCl 2 + (NH 4 ) 2 SO 4  BaSO 4 + 2NH 4 Cl AgNO 3 + KBr  AgBr + KNO 3 AgNO 3 + KBr  AgBr + KNO 3 LiCl + NaOH  LiOH + NaCl LiCl + NaOH  LiOH + NaCl 3CaS + 2Fe(C 2 H 3 O 2 ) 3  3Ca(C 2 H 3 O 2 ) 2 + Fe 2 S 3 3CaS + 2Fe(C 2 H 3 O 2 ) 3  3Ca(C 2 H 3 O 2 ) 2 + Fe 2 S 3 3K 2 CO 3 + 2Na 3 PO 4  2K 3 PO 4 + 3Na 2 CO 3 3K 2 CO 3 + 2Na 3 PO 4  2K 3 PO 4 + 3Na 2 CO 3 K 2 CO 3 + CuI 2  2KI + CuCO 3 K 2 CO 3 + CuI 2  2KI + CuCO 3