South Pasadena • Chemistry Name Period Date 5 · Chemical Reactions SINGLE REPLACEMENT WORKSHEET 1. The balanced equation for the reaction between aluminum and lead nitrate: 2 Al + 3 Pb(NO3)2 3 Pb + 2 Al(NO3)3 The elements and ions involved are: The charges are: The half-reaction involving Al is: Al Al + 3 e 3+ Al Pb2+ 0 +2 NO3– Pb Al3+ 0 +3 NO3– The half-reaction involving Pb is: – Pb2+ + 2 e– Pb The charge on Al is changing from 0 to +3. The charge on Pb is changing from +2 to 0. Because it’s getting more [ positive | negative ], so Because it’s getting more [ positive | negative ], so Al is [ gaining | losing ] electrons Pb is [ gaining | losing ] electrons and is being [ oxidized | reduced ]. and is being [ oxidized | reduced ]. 2. Predict the products and write the balanced equation for each reaction. Then identify the element that is oxidized and reduced, and write the half-reactions. (a) Magnesium metal is placed in a solution of nickel chloride. BALANCED EQUATION: Mg + NiCl2 Ni + MgCl2 Ni0 Mg2+ CHARGES Mg0 Ni2+ OXIDATION HALF-REACTION: REDUCTION HALF-REACTION Mg Mg2+ + 2 e− Ni2+ + 2 e− Ni ELEMENT THAT IS OXIDIZED: ELEMENT THAT IS REDUCED: Mg (b) Ni Chlorine gas is bubbled in a solution of potassium bromide. BALANCED EQUATION: Cl2 + 2 KBr Br2 + 2 KCl CHARGES Cl0 OXIDATION HALF-REACTION: 2 Br− Br2 + ELEMENT THAT IS OXIDIZED: Br Br− Br0 Cl− REDUCTION HALF-REACTION 2 e− Cl2 + 2 e− 2 Cl− ELEMENT THAT IS REDUCED: Cl (c) Zinc metal is placed in a solution of hydrochloric acid. BALANCED EQUATION: Zn + 2 HCl H2 + ZnCl2 H0 Zn2+ CHARGES Zn0 H+ OXIDATION HALF-REACTION: REDUCTION HALF-REACTION − 2 H+ + 2 e− H2 Zn Zn + 2 e 2+ ELEMENT THAT IS OXIDIZED: ELEMENT THAT IS REDUCED: Zn (d) H Iron metal is placed in a solution of cupric sulfate to form a ferric sulfate solution. BALANCED EQUATION: 2 Fe + 3 CuSO4 3 Cu + Fe2(SO4)3 CHARGES Fe0 Cu2+ Cu0 OXIDATION HALF-REACTION: REDUCTION HALF-REACTION Fe Fe3+ + 3 e− Cu2+ + 2 e− Cu ELEMENT THAT IS OXIDIZED: ELEMENT THAT IS OXIDIZED: Fe (e) Fe3+ Cu Copper metal is placed in a solution of silver nitrate to form a cupric nitrate solution. BALANCED EQUATION: Cu + 2 AgNO3 2 Ag + Cu(NO3)2 Cu0 Ag0 CHARGES Ag+ OXIDATION HALF-REACTION: REDUCTION HALF-REACTION Cu Cu2+ + 2 e− Ag+ + e− Ag ELEMENT THAT IS OXIDIZED: ELEMENT THAT IS OXIDIZED: Cu (f) Cu2+ Ag Sodium metal is placed in water. (Hint: write water as HOH.) BALANCED EQUATION: 2 Na + 2 HOH H2 + 2 NaOH CHARGES Na0 OXIDATION HALF-REACTION: Na Na+ + e− ELEMENT THAT IS OXIDIZED: Na H+ H0 Na+ REDUCTION HALF-REACTION 2 H+ + 2 e− H2 ELEMENT THAT IS OXIDIZED: H
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