NAME THAT PRODUCT - PREDICTING THE PRODUCTS OF CHEMICAL REACTIONS

ANSWER KEY

The products are shown for each chemical reaction.  An X is placed in the correct cell in the tables below each reaction. 

1.  Na2SO4(aq) + Pb(NO3)2(aq) 2NaNO3(aq) + PbSO4(s)
PRECIPITATION RX
- mixing 2 aqueous salt solutions. With Pb, think precipitation.  The spectator ions are sodium and nitrate.

reaction type acid/base  redox precipitationX none of these

2.  2C2H6(g) + 7O2(g) 4CO2(g) + 6H2O(g)

REDOX RX - pure element in reactants (O2) disappears into compound of oxygen; ox. # of O on left is 0, on right -2, implying that O is reduced and acts as an oxidizing agent. The average Ox. # of C in C2H6 is 3- (each H is 1+ for total of 6+ so avg C is 3-). Ox. # of C in CO2 is 4+. Hence C is oxidized and is a reducing agent.  Clearly redox reaction. No simple proton donor or acceptor, and no aqueous solutions being mixed.

reaction type acid/base  redox X precipitation none of these

3.  2NaOH(aq) + MnSO4(aq) Na2SO4(aq) + Mn(OH)2(s)

PRECIPITATION RX - mixing two aqueous salt solution in which each dissociated into ions. Even though NaOH is a strong base, there is not proton donor with which to react. The strong base is the source of OH- ions which precipitate with Mn ions. Clearly not redox. Remember most sulfates are soluble except salts of calcium barium, lead, mercury, and silver. Spectator ions are sodium and sulfate.

reaction type acid/base  redox precipitationX none of these

4.  2HCl(aq) + Pb(NO3)2(aq) 2HNO3(aq) + PbCl2(s)

PRECIPITATION RX - mixing two aqueous solutions in which each dissociated into ions. One might argue that this is an acid/base reaction as well since the strong acid HCl is donating a proton to a weak base NO3 to form the strong acid HNO3. However, nitrate is a spectator ion and doesn't participate in the reaction. The "driving force" for the reaction is the formation of the precipitate The strong acid is the source of Cl- ions. Clearly not a redox. Cl on both sides has an ox. # of 1-.  Spectator ions are hydrogen (hydronium) and nitrate.

reaction type acid/base  redox precipitationX none of these

5.  3 HNO3(aq) + Al(OH)3(s)   Al(NO3)3(aq) + 3H2O(l)

ACID/BASE RX - HNO3 is nitric acid, a strong acid and a strong electrolyte. Is there anything around to protonate or possibly precipitate? Clearly there is - Al(OH)3(s). It is a solid but presumably would dissolve and the OH- -  a strong base - reacts with the nitric acid and is protonated by the strong acid HNO3. It can't be a precipitation reaction since start with a solid reactant. Isn't a redox rx like in lab 3 - HNO3 + Cu(s), in which pure Cu dissolved and reacted to form Cu2+ ions. Al already exists as Al3+ ions.

reaction type acid/base  X redox precipitation none of these

6.  Ca(OH)2(s) + 2HCl(aq) 2H2O(l) + CaCl2(aq)

ACID/BASE RX - Have a strong acid (HCl) and a strong base (Ca(OH)2) which is sparingly soluble. All Cl1- salts except Ag, Hg, and Pb are soluble. No redox reaction when have obvious strong acid and base. 

reaction type acid/base  X redox precipitation none of these

7.  Cu(s) + 2AgNO3(aq) Cu(NO3)2(aq) + 2Ag(s)

REDOX RX - Clearly no acid or base; don't have two aqueous salt solutions to mix. Ox. # of Cu goes from 0 to 2+ (hence copper is oxidized and is a reducing agent) while Ag goes from 1+ to 0 (hence silver ion is reduced and is an oxidizing agent). Pure element disappear into compounds or form from a compound of the element.  This reaction would go only if Cu and Ag+ are better reducing agent and oxidizing agent, respectively, than the appropriate products, as we will  in the activity series lab.

reaction type acid/base  redox X precipitation none of these

8.  Zn(s) + 2HCl(aq) ZnCl2(aq) + H2(g)

REDOX RX - This is from Lab 3. Excess Zn(s) dissolves in HCl and is oxidized to Zn2+ ions - hence it is a reducing agent). Even though one of the reactants is a strong acid, there is clearly no proton acceptor to accept. Likewise, don't have two aqueous ionic solutions mixing to form a solid. Zn ox. # goes form 0 to 2+ (hence it is oxidized and acts as a reducing agent) while H in HCl goes from 1+ to 0 (so it gets reduced and acts as oxidizing agent).  Zn is higher in the activity series than H2 and hence displaces it from a compound of H. 

reaction type acid/base  redox X precipitation none of these

9.  H2SO4(aq) + BaCl2(aq) BaSO4(s) + 2HCl(aq)

PRECIPITATION RX - Even though one of the reactants is a strong acid (H2SO4), it also is a source of ions that can form a precipitate with Ba2+. In this reactions, two ionic solutions are being mixed to form a precipitate. Solubility rules show that BaSO4 is insoluble in water. One could argue that this is an acid base reaction as well since the acid (proton donor) is donating protons to a very weak base Cl- to form HCl. However, Cl ion is a spectator ion and doesn't participate in the reaction. The "driving force" for the reaction is the formation of the precipitate.

reaction type acid/base  redox precipitationX none of these

10.  H2SO4(aq) + 2KOH(aq) K2SO4(aq) + 2H2O(l)

ACID/BASE RX - In this rx, a strong acid reacts with a strong base. Both acid and base are strong electrolytes in water. There is no change in oxid. # from reactants to products. Likewise, there is no precipitate formed.

reaction type acid/base  X redox precipitation none of these

11.  C6H12O6(s-glucose) + 6O2(g) 6CO2(g) + 6H2O(g)

REDOX RX - This is an example of the oxidation of a carbohydrate with oxygen to form carbon dioxide and water - a reaction that goes on within us as you read this. A pure element (O2) disappears to form a compound of that element. The oxid # of O in O2 is O and goes to 2- in CO2 and H2O - hence it is reduced and acts as an oxidizing agent. The average oxidation number of C in C6H12O6 is 0, since each H is 1+ and each O is 2-. The oxid # of C in CO2 is 4+. Hence it is oxidized.   Clearly there is not precipitation reaction and no simple proton transfer.

reaction type acid/base  redox X precipitation none of these

12. FeCl3(aq) + 3KOH(aq) Fe(OH)3(s) + 3KCl(aq)

PRECIPITATION RX - Even though KOH is a strong base, there is no proton donor to interact with the OH-. Therefore it is not an acid/bse reaction. Solubility rules show that Fe(OH)3 should be insoluble. When you hear hoofsteps, don't think zebras!  Potassium and choride are spectator ions.

reaction type acid/base  redox precipitationX none of these

13.  NaNO3(aq) + HCl(aq) HNO3(aq) + NaCl(aq)

NO REACTION - All sodium salts are soluble; all nitrates are soluble. One could argue that it is an acid/base reaction, where HCl donates a proton to the weak base NO3- to form HNO3. The problem with that is that HNO3 is a strong acid itself, which completely dissociates. Therefore, NO3- is a spectator ion throughout. Nothing changes. Everything is a strong electrolyte.

reaction type acid/base  redox precipitation none of these X

14.   2Na3PO4(aq) + 3Pb(NO3)2 Pb3(PO4)2(s) + 6NaNO3(aq)

PRECIPITATION RX - mixing 2 aqueous salt solutions. No acids/base around.  When you see Pb, think precipitate.   Sodium and nitrate are spectator ions.

reaction type acid/base  redox precipitationX none of these

15.  2Mg(s) + O2(g) 2MgO(s)

REDOX RX. - Clearly this can't be an acid/base or precipitation reaction. Two pure elements disappear into a compound of that element. Pure elements have an oxidation number of 0.  Mg is oxidized by the oxidizing agent oxygen.

reaction type acid/base  redox X precipitation none of these

16.   2 NH4Cl(aq) + K2SO4(aq) (NH4)2 SO4(aq) + 2KCl(aq)

NO REACTION - Two aqueous salt solutions mixed together, but both new products are soluble. All ions are spectator ions/

reaction type acid/base  redox precipitation none of these X

17.  HF(aq) + KOH(aq) H2O(l) + KF(aq)

ACID/BASE RX - KOH is a strong base, and HF (similar to HCl) must be a proton donor or acid. No change in oxidation number occurs, and clearly no precipitation reaction occurs

reaction type acid/base  X redox precipitation none of these

The following reactions are from the copper experiment:  They are already balanced for you. Click on the links to see videos of the reactions you did in lab!

18.  Cu(s) + 4HNO3(aq) --> Cu(NO3)2(aq) + 2NO2(g) + 2H2O(l)

REDOX RX - Clearly, a pure element, Cu(s) disappears into a compound of that element.  The oxidation number of N changes from 5+ in HNO3 to 4+ in NO2.  Notice the 2 of the 4 nitrates from the reactant side remain as products in copper nitrate.  Its hard to categorize this reaction with respect to a composition change.  In part, Cu displaces NO2 from its compounds, so its a displacement.  However part of the nitrate from nitric acid remains, so its more complicated than that. 

reaction type acid/base  redox X precipitation none of these

19.  Cu(NO3)2(aq) + 2NaOH(aq) ---> Cu(OH)2(s) + 2NaNO3(aq)

PRECIPITATION RX - This is a classic case of two aqueous salt solutions which form an insoluble salt.  Remember, most hydroxides are insoluble.  It can't be a acid/base reaction since there is not proton donor.

reaction type acid/base  redox precipitationX none of these

20.  Cu(OH)2(s) heat > CuO(s) + H2O(l)

ACID/BASE RX - This is a bit tricky, since where is the acid in the reactants?  The base is there - OH.  Notice, however, that there are two OH's in the reactant.  Remember that an acid and base react to form another acid and base.   Look at the products and consider the reverse reaction.  An O2- from copper oxide, which is clearly a base, reacts with water as an acid, which donates a proton to the oxide, to form 2 OH 's - one from oxide gaining a proton and one from water which loses a proton.  Now consider the forward reaction again.  One OH acts as an acid and becomes oxide, while one acts as a base and becomes water.  It's not a precipitation reaction since you start with a solid and end with a solid.

reaction type acid/base  X redox precipitation none of these

21.  CuO(s) + H2SO4 ---> CuSO4(aq) + H2O(l)

ACID/BASE RX - Clearly, a strong acid (sulfuric acid) reacts with a strong base (copper oxide) to form a salt and water.  Notice that the base does not have to be soluble in water for it to react with the strong acid.

reaction type acid/base  X redox precipitation none of these

22.  CuSO4(aq) + Zn(s) ---> Cu(s) + ZnSO4(aq)

REDOX - Here, a pure element (Zn, oxidation number of 0) disappears into a compound of that element (ZnSO4 - oxidation number of Zn = 2+).  Zn is oxidized and acts as an reducing agent.  Likewise, the pure element Cu appears from a compound of copper as Cu2+ is reduced. 

reaction type acid/base  redox X precipitation none of these

23.  Zn(s)  +  HCl(aq) ---> ZnCl2(aq) + H2(g)

same as Rx 8 above.

reaction type acid/base  redox precipitation none of these