Single replacement reactions - PDF Free Download

Today s focus.

Single replacement reactions 1. Learn to predict Single replacement reaction If and when a reaction occurs, what are the products? 2. Learn to write Single replacement reaction: (i) Balanced chemical reaction (ii) Net ionic reaction (iii) Identify which species is oxidized, and which species is reduced (iv) Identify spectator ions in the reaction

Using Activity Series of Metals Involving the halogens Today we will focus on single replacement reactions of metals.

Single replacement reactions involving metals ACTIVITY SERIES OF METALS This is a REFERENCE table. Not to be memorized.

Single replacement reactions involving metals ACTIVITY SERIES OF METALS The more reactive metals at the top of the table. This is a REFERENCE table. Not to be memorized. You are responsible to know how to use it. The less reactive metals at the bottom of the table. Table shows oxidation reactions: Metals at the top of the table are active metals and they lose their electron(s) easily (i.e. They are easily oxidized.) E.g. Li (s) Li + (aq) + e Lithium metal is oxidized. The opposite process of oxidation is Reduction, where the metal ions gain electron(s). E.g. Li + (aq) + e Li (s) (Electrons written on the LHS) Lithium ion is reduced. (Electrons written on the RHS)

Single replacement reactions involving metals ACTIVITY SERIES OF METALS (Most active) Q: Compare the positions of Magnesium and Zinc. Which is higher on the Activity Series of Metals? A: Mg is higher on the table. Mg is a more active metal than Zn. What does this mean? Consider an experiment: What happens if you dip Mg metal into a Zn 2+ (aq) solution? Mg (Least active) What is happening in the beaker of Zn(NO 3 ) 2 solution?

Single replacement reactions involving metals Starting Materials: 1. Mg(s) 2. Zn(NO 3 ) 2 (aq) Mg Zinc deposits on the Mg metal Zn 2+ (aq) + 2 e Zn(s) Magnesium dissolves in the solution Mg(s) Mg 2+ (aq) + 2 e Two processes happening: Net ionic reaction: Q: What happened to the NO 3 (aq) ions? Balanced chemical reaction: Mg (s) + Zn(NO 3 ) 2 (aq) Mg(NO 3 ) 2 (aq) + Zn (s) A + BC AC + B Oxidation: Mg(s) Mg 2+ (aq) + 2 e Reduction: Zn 2+ (aq) + 2 e Zn(s) Mg(s) + Zn 2+ (aq) Zn(s) + Mg 2+ (aq) A: NO 3 ions remain in solution. They did not participate in the reaction. Mg metal dissolves and displaces Zn 2+ ions from solution because Mg is higher on the Activity Series of Metals than Zn. Mg (s) is oxidized. Zn 2+ (aq) is reduced. NO 3 are spectator ions.

Single replacement reactions involving metals ACTIVITY SERIES OF METALS (Most active) Q: Compare the positions of Copper and Zinc. Which is higher on the Activity Series of Metals? A: Zn is higher on the table. Zn is more active than Cu. What does that mean? Consider an experiment: What happens if you dip Cu metal into a Zn 2+ (aq) solution? Cu (Least active) What is happening in the beaker of Zn(NO 3 ) 2 solution?

Single replacement reactions involving metals Cu Zn 2+ ions stay in solution Because Cu is lower on the Activity Series of Metals than Zinc, Copper does not dissolve in the Zn 2+ solution Balanced chemical reaction: No reaction. Since Cu is lower on the Activity Series of Metals than Zinc, Cu metal cannot displace Zn 2+ ions from the solution.

Single replacement reactions involving metals SUMMARY ACTIVITY SERIES OF METALS (Most active) Mg Mg (s) is oxidized. Zn 2+ (aq) is reduced. NO 3 are the spectator ions. Balanced chemical reaction Net ionic reaction Mg (s) + Zn(NO 3 ) 2 (aq) Mg(NO 3 ) 2 (aq) + Zn (s) Mg(s) + Zn 2+ (aq) Zn(s) + Mg 2+ (aq) Cu No reaction (Least active) RULE: The metal (Mg) has to be more active than the metal ions in solution (Zn 2+ ) in order to displace the ions from the solution. Otherwise, no reaction occurs.

Single replacement reactions involving metals Consider these metals: What happens when they are dipped into different solutions? Can we predict if there is a reaction?

Single replacement reactions involving metals Consider these metals: B C B C B C B C What happens when the metals are dipped into the different solutions? A reaction may or may not occur. But if there is a reaction, it will follow the Single Replacement reaction format to form the products, AC + B.

Single replacement reactions involving metals Let s dip copper into the solutions. http://group.chem.iastate.edu/greenbowe/sections/projectfolder/flashfiles/redox/home.html

Single replacement reactions involving metals Copper is dipped into the solutions. Let s remove the copper from the solutions. No reaction No reaction No reaction Reaction occurs! Let s record observations on the worksheet.

Single replacement reactions involving metals ACTIVITY SERIES OF METALS Let s write the reaction for Cu (s) in AgNO 3 (aq). (NR = no reaction) NR No NR No Yes Yes

Single replacement reactions involving metals Cu Starting Materials: 1. Cu(s) 2. AgNO 3 (aq) e e Silver deposits on the Cu metal Ag + (aq) + e Ag(s) Copper dissolves in the solution Cu(s) Cu 2+ (aq) + 2 e Balanced chemical reaction: Cu (s) + 2 AgNO 3 (aq) Cu(NO 3 ) 2 (aq) + 2 Ag (s) NO 3 are spectator ions. Two processes happening: Cu (s) is oxidized. Ag + (aq) is reduced. Oxidation: Cu(s) Cu 2+ (aq) + 2 e Reduction: 2 Ag + (aq) + 2 e 2 Ag(s) Cu(s) + 2 Ag + (aq) 2 Ag(s) + Cu 2+ (aq) Net ionic reaction

Single replacement reactions involving metals http://group.chem.iastate.edu/greenbowe/sections/projectfolder/flashfiles/redox/home.html Continue with Activity 1, 2, and 3. NR No NR No Yes Yes For every reaction, 1. Write the balanced overall chemical reaction. 2. Write the balanced net ionic reaction. 3. Determine the species oxidized. 4. Determine the species reduced. 5. Identify the spectator ion(s).

Single replacement reactions involving metals ACTIVITY SERIES OF METALS (Most active) Activity 4 Compare the positions of the Metal and Hydrogen. Q: Will the metal under consideration react with hydrogen ions in solution to displace H 2 from the solution? (Least active)

Single replacement reactions involving metals ACTIVITY SERIES OF METALS (Most active) Activity 4 Q: Will the Mg (s), Pb (s), and Ag (s) react with hydrogen ions in an HCl solution to displace H 2 from the solution? Reaction Reaction No occurs! occurs! Reaction Mg (s) Pb (s) Ag (s) Bubbles shows the formation of H 2 (g) as H + (aq) is displaced from the solution. The more bubbles, the faster the reaction. RULE: The metal (Mg and Pb) has to be more active than H + ions in solution in order to displace H 2 (g) from the solution. (Least active) Let s write the reaction involving Mg (s) in HCl solution.

Single replacement reactions involving metals Starting Materials: 1. Mg(s) 2. HCl (aq) Mg e e Cl Cl Hydrogen forms as H 2 gas. 2 H + (aq) + 2 e H 2 (g) Cl Cl Mg dissolves in the solution Mg (s) Mg 2+ (aq) + 2 e Cl are spectator ions. Two processes happening: Mg (s) is oxidized. H + (aq) is reduced. Oxidation: Reduction: Balanced chemical reaction: Mg (s) + 2 HCl (aq) MgCl 2 (aq) + H 2 (g) Mg(s) Mg 2+ (aq) + 2 e 2 H + (aq) + 2 e H 2 (g) Mg(s) + 2 H + (aq) H 2 (g) + Mg 2+ (aq) Net ionic reaction

Single replacement reactions involving metals ACTIVITY SERIES OF METALS No 3 Continue with Activity 4. Yes Yes 1 2 For every reaction, 1. Write the balanced overall chemical reaction. 2. Write the balanced net ionic reaction. 3. Determine the species oxidized. 4. Determine the species reduced. 5. Identify the spectator ion(s).

Finish the worksheet: Activity 1, 2, 3, 4 http://group.chem.iastate.edu/greenbowe/sections/projectfolder/flashfiles/redox/home.html Try some practice problems in Maple TA. Use Dimensional Analysis in ALL your calculations!!

Involving the halogens Today we will focus on single replacement reactions involving the halogens.

Today s focus.

Single replacement reactions involving the Halogens

Single replacement reactions involving the Halogens Rule 1: If a The most reactive halogen is Fluorine, located at the top of the table. more reactive halogen comes into contact with a compound containing a less reactive halogen, a chemical reaction will take place. When the reaction occurs, the less reactive halogen is displaced from the compound and replaced by the more reactive halogen. Hence, the name SINGLE REPLACEMENT reaction. Unlike metals, the halogens form NEGATIVE ions. Forms 1 charge ions. This is a order of the elements as they appear on the Periodic Table. Not to be memorized. You are responsible to know how to use it. The least reactive halogen is Iodine, located at the bottom of the table. We will not be concerned with Astatine because it is radioactive.

Single replacement reactions involving the Halogens Rule 2: If a The most reactive halogen is Fluorine, located at the top of the table. less reactive halogen comes into contact with a compound containing a more reactive halogen, no chemical reaction will take place. Unlike metals, the halogens form NEGATIVE ions. Forms 1 charge ions. This is a order of the elements as they appear on the Periodic Table. Not to be memorized. You are responsible to know how to use it. The least reactive halogen is Iodine, located at the bottom of the table. We will not be concerned with Astatine because it is radioactive.

Single replacement reactions involving the Halogens Q: What happens when bromine in water and an aqueous solution of sodium iodide are mixed together? If there is a reaction, write the balanced chemical reaction, net ionic reaction, identify the species oxidized, reduced, and the spectator ions. Step 1: Identify the reacting species. Br 2 (aq) + NaI (aq) Step 2: What type of reactions is this? Single replacement reaction Haven t covered. Step 3: SR Involving metals or the Halogens? Since there is only one metal, Na, in the reacting species, this reaction cannot be SR involving metals. (Clue: There is no 2 nd metal to compare with.) Therefore, this must be SR involving the Halogens. (Clue: There are two non metals to compare, Bromine and Iodine.) Bromine, Rule 1 applies, a reaction occurs. Step 4: Which is more reactive, Bromine or Iodine? Step 5: Write the balanced chemical reaction. Br 2 (aq) + 2NaI (aq) I 2 (aq) + 2NaBr (aq) Step 6: Identify the spectator ions, the species oxidized and reduced? Step 7: Write the net ionic reaction? Na + (aq) I (aq) Br 2 (aq) Br 2 (aq) + 2 I (aq) I 2 (aq) + 2 Br (aq)

Single replacement reactions involving the Halogens https://www.youtube.com/watch?v=tnverqfmdxo Balanced chemical reaction: Net ionic reaction: Br 2 (aq) + 2NaI (aq) I 2 (aq) + 2NaBr (aq) Br 2 (aq) + 2 I (aq) I 2 (aq) + 2 Br (aq)

Single replacement reactions involving the Halogens https://www.youtube.com/watch?v=zd9fsyxpyum Balanced chemical reaction: I 2 (aq) + NaCl (aq) No reaction, because iodine is less active than chlorine.

Single replacement reactions involving the Halogens Try the second worksheet!