# 5. Reactions in Solution Precipitation # Page 14 #### Partner: Jeff Somvorachith #### 10/31/24 ## Lab 5. Reactions in Solution Precipitation Purpose: To practice identifying reactions that result in precipitation and practice recognizing and writing equations for double replacement reactions by testing pairs of reagents and looking for signs of chemical change and writing molecular and ionic equations for the reactions. Prelab: 1. 1. a. Zinc Sulfide: ZnS b. Chromium(III) Hydroxide: Cr(OH)3 c. Lead(II) Phosphate: Pb3(PO4)2 2. a. Sodium Chloride: NaCl->Na++Cl- b. Copper(II) Chloride: CuCl2->Cu2++2Cl- c. Iron(III) Sulfate: Fe2(SO4)3->2Fe3++3SO42- 3. Fe(NO3)3+K2CO3->Fe2(CO3)3 (s)+KNO3 4. 0.2M\*1L=M1\*2L M1=0.1M Procedure: 1. Use 4-5 drops of each reagent for each pair of your tests. Note and record any sign of reaction. Test all possible pair of combinations of one group A reagent with one group B reagent. Record your observations in the data table in your notebook. Recall that not all pairs will react, and that sometimes the evidence of reaction, especially formation of a precipitate, take a few moments to appear. 2. If there are any combinations about which you doubt, repeat the tests. 3. Return pipettes containing unused portions of the reagent # Page 15 solutions to the proper location. Some of the solutions contain transition metal ions, so should not be washed down the drain. Instead, dump the contents onto a paper towel in the tray labeled "transition metal waste". Wash some items with water and clean others with cotton swabs. Safety: Barium is toxic, don't touch. wash hands thoroughly. Data Table:
CoCl2 CuCl2 AlCl3 BaCl2 NiCl2
NaI No Reaction Turned Brown, Precipitated No Reaction No Reaction No Reaction
Na2CO3 Precipitated Precipitated Precipitated Precipitated Precipitated
Na3PO4 Tuned Purple, Precipitated Precipitated Precipitated Precipitated Precipitated
Na2SO4 No Reaction No Reaction No Reaction Precipitated No Reaction
NaOH Turned Purple, Precipitated Precipitated Precipitated Precipitated Precipitated
# Page 16 Conclusion: a. Formula of Precipitates
CoCl2 CuCl2 AlCl3 BaCl2 NiCl2
NaI CuI2
Na2CO3 CoCO3 CuCO3 Al2(CO3)3 BaCO3 NiCO3
Na3PO4 Co3(PO4)2 Cu3(PO4)2 AlPO4 Ba3(PO4)2Ni3(PO4)2
Na2SO4 BaSO4
NaOH Co(OH)2 Cu(OH)2 Al(OH)3 Ba(OH)2 Ni(OH)2
b. Molecular Formulas CuCl2​(aq)+2NaI(aq)->2CuI2(s)+2NaCl(aq) CoCl2​(aq)+Na2​CO3​(aq)->CoCO3​(s)+2NaCl(aq) CuCl2​(aq)+Na2​CO3​(aq)->CuCO3​(s)+2NaCl(aq) 2AlCl3​(aq)+3Na2​CO3​(aq)->Al2​(CO3​)3​(s)+6NaCl(aq) BaCl2​(aq)+Na2​CO3​(aq)->BaCO3​(s)+2NaCl(aq) NiCl2​(aq)+Na2​CO3​(aq)->NiCO3​(s)+2NaCl(aq) 3CoCl2​(aq)+2Na3​PO4​(aq)->Co3​(PO4​)2​(s)+6NaCl(aq) 3CuCl2​(aq)+2Na3​PO4​(aq)->Cu3​(PO4​)2​(s)+6NaCl(aq) AlCl3​(aq)+Na3​PO4​(aq)->AlPO4​(s)+3NaCl(aq) 3BaCl2​(aq)+2Na3​PO4​(aq)->Ba3​(PO4​)2​(s)+6NaCl(aq) 3NiCl2​(aq)+2Na3​PO4​(aq)->Ni3​(PO4​)2​(s)+6NaCl(aq) BaCl2​(aq)+Na2​SO4​(aq)->BaSO4​(s)+2NaCl(aq) CoCl2​(aq)+2NaOH(aq)->Co(OH)2​(s)+2NaCl(aq) CuCl2​(aq)+2NaOH(aq)->Cu(OH)2​(s)+2NaCl(aq) AlCl3​(aq)+3NaOH(aq)->Al(OH)3​(s)+3NaCl(aq) BaCl2​(aq)+2NaOH(aq)->Ba(OH)2​(s)+2NaCl(aq) NiCl2(aq)+2NaOH(aq)->Ni(OH)2(s)+2NaCl(aq) # Page 17 #### 11/1/24 c. Net ionic formulas Cu2++2I+->CuI2 Co2++Co32-->CoCO3 Cu2++Co32+->CoCO3 2Al3++3CO32-->Al2(CO3)3 Ba2++CO32-->BaCO3 Ni2++CO32-->NiCO3 3Co2++2PO43-->Co3(PO4)2 3Cu2++2PO43-->Cu3(PO4)2 Al3++PO43-->AlPO4 3Ba2++2PO43-->Ba3(PO4)2 3Ni2++2PO43-->Ni3(PO4)2 Ba2++SO42-->BaSO4 Co2++2OH-->Co(OH)2 Cu2++2OH-->Cu(OH)2 Al3++3OH-->Al(OH)3 Ba2++2OH-->Ba(OH)2 Ni2++2OH-->Ni(OH)2