The Activity Series. Topic 9.1

easily oxidized (more -) easily reduced (more +)

ranks metals according to the ease they undergo oxidation o higher up metals are more reactive displace those lower down from a solution o notice hydrogen in the series metals above H will react in weak acids metals below will not react with weak acids activity series is in section 25 of data booklet

the most reactive metal ends up as an ion and then reacts to form a new compound o Zn + CuSO 4  Cu + ZnSO 4 Zn is more reactive than Cu Zn is oxidized (goes from 0 to +2) and then bonds with the -2 SO 4 o Ni + 2AgNO 3  2Ag + Ni(NO 3 ) 2 Ni is more reactive that Ag Ni is oxidized (goes from 0 to +1) and then bonds with the -1 NO 3

o Ag + Zn(NO 3 ) 2  Ag + Zn (NO 3 ) 2 Zn is more reactive than Ag no reaction o Zn will stay a 2+ ion and remain bonded to the 1- nitrate o Mg + 2 H +  ? Mg is more reactive than H o becomes an ion o Mg + 2 H +  H 2 + Mg 2+

o Na + + Al  ? Na is more reactive that Al no reaction, Na + will remain a ion

Nonmetals Which can occur? Cl 2 + 2I -  I Cl- I Cl -  Cl I - Yes No

Consider the following reactions of three unknown metals X, Y and Z. 2XNO 3 (aq) + Y(s) → 2X(s) + Y(NO 3 ) 2 (aq) Y(NO 3 ) 2 (aq) + Z(s) → No reaction 2XNO 3 (aq) + Z(s) → 2X(s) + Z(NO 3 ) 2 (aq) What is the order of increasing reactivity of the metals (least reactive first)? X < Z < Y

Some of the following is not in the IB syllabus but is often assumed you will know

Watch These Reactions!

Combination (Synthesis) Reactions a chemical change in which two or more substances react to form a single new substance the general form is A + X  AX o 2Cu(s) + S(s)  Cu 2 S(s) o 2Fe(s) + 3S(s)  Fe 2 S 3 (s) o 2K(s) + Cl 2 (g)  2KCl

Decomposition Reactions a chemical change in which a single compound breaks down into two or more simple products. the general form is AX  A + X o 2HgO( s ) → 2Hg( l ) + O 2 ( g ) o Zn(ClO 3 ) 2  ZnCl 2 + 3O 2 o H 2 O( l ) → ? H 2 O( l ) → H 2 ( g ) + O 2 ( g ) 2H 2 O( l ) → 2H 2 ( g ) + O 2 ( g ) electricity

Single Replacement Reactions a chemical change in which one element replaces a second element in a compound o metal will replace a metal, or a nonmetal will replace a nonmetal o general form is A + BX  AX + B o Zn ( s ) + 2HCl ( aq )  ZnCl 2 ( aq ) + H 2 ( g ) Zn more reactive that H so is oxidized (0 to +2) and bonds with the negative Cl

Al + Fe 2 O 3  ? o aluminum more reactive, will become and ion, and will replace iron(III) o 2Al + Fe 2 O 3  2Fe + Al 2 O 3 Cl 2 +2 NaI  ? o Cl more reactive that I, will become an ion and replace I o Cl 2 +2NaI  2 NaCl + I 2

Double Replacement Reactions an exchange of positive ions between two chemicals general form is AX + BY  BX + AY reaction occurred if a gas, a precipitate, or water is formed CuSO 4 + Na 2 CO 3  Na 2 SO 4 + CuCO 3

NaOH + CuSO 4  ? o the Na + and Cu 2+ switch places. o Na + combines with SO 4 2- to form Na 2 SO 4. o Cu 2+ combines with OH - to form Cu(OH) 2 o NaOH + CuSO 4  Na 2 SO 4 + Cu(OH) 2 o 2NaOH + CuSO 4  Na 2 SO 4 + Cu(OH) 2

Na 2 CO 3 + HCl  ? o Na +1 combines with Cl -1 to form NaCl o H + combines with CO 3 2- to form H 2 CO 3 o Na 2 CO 3 + 2HCl  2NaCl + H 2 CO 3 this reaction does not normally happen this way It is a metal carbonate in a strong acid, so… o Na 2 CO 3 +2HCl--> 2NaCl+CO 2 +H 2 0

Combustion Reaction a type of combination reaction where a substance reacts with oxygen often the burning of a fuel that produces carbon dioxide, water, light, and heat

CH 4 + O 2  ? o CH 4 + O 2  CO 2 + H 2 O o CH 4 + 2O 2  CO 2 + 2H 2 O

Practice Classify each of the following as to type: H 2 + Cl 2  2HCl o combination Ca + 2H 2 O  Ca(OH) 2 + H 2 o single replacement

Practice 2CO + O 2  2CO 2 o combination and combustion 2KClO 3  2KCl + 3O 2 o decomposition

Practice FeS + 2HCl  FeCl 2 + H 2 S o double replacement Zn + HCl  ? o single replacement o Zn + 2HCl  ZnCl 2 + H 2