Chem 111 Precipitation & Net Ionic Equations Name:______

Chapters 17 – Net Ionic Equations Today’s exercise involves prediction, observation, and drawing conclusions about the solubility chemistry of ionic compounds. 1. Teams of 4 students will spend 20 minutes guessing possible outcomes of reactions #1-5. 2. I will demonstrate each reaction (#1-#5) on the overhead projector. Record your observations. 3. Team up again and write reactions for #6 – 12. Spend 10 minutes doing this, then I’ll demonstrate them. 4. Your team will answer the questions on the last pages. Hints:  The precipitation equations should represent a “double-displacement precipitation” reaction (cations trade anions with each other). Write each one as if you know it will happen. We’ll cross the ones that didn’t go out later.  Note that all reactant solutions represent soluble compounds!  Be sure to write the phase on every chemical.  If no precipitate is formed when we do the demonstration, scratch out the precipitation equation that you wrote.

Probably # Soln. #1 Soln. #2 Predicted Precipitation Equation Precip? Observations Soluble?

+ - + - Ag (aq) + NO3 (aq) + Na (aq) + Cl (aq)  + - AgCl (s) + Na (aq) + NO3 (aq) (TOTAL)

+ - + - 0 AgNO3 (aq) NaCl (aq) Ag (aq) + NO3 (aq) + Na (aq) + Cl (aq)  + - AgCl (s) + Na (aq) + NO3 (aq) Ag+(aq) + Cl- (aq)  AgCl (s) (NET) Probably # Soln. #1 Soln. #2 Predicted Precipitation Equation Precip? Observations Soluble?

1 AgNO3 (aq) NaI (aq)

Na SO 2 AgNO (aq) 2 4 3 (aq)

3 Pb(NO3)2 NaCl (aq)

4 Pb(NO3)2 NaI (aq)

Na SO 5 Pb(NO ) 2 4 3 2 (aq)

NaOH 6 NaNO3 (aq) (aq) Probably # Soln. #1 Soln. #2 Predicted Precipitation Equation Precip? Observations Soluble?

NaOH 7 Mg(NO3)2 (aq) (aq)

NaOH 8 Ni(NO3)2 (aq) (aq)

NaOH 9 Cr(NO3)3 (aq) (aq)

NaOH 10 Zn(NO3)2 (aq) (aq)

NaOH 11 AgNO3 (aq) (aq)

NaOH 12 Pb(NO3)2 (aq) (aq) Questions 1. Circle the cations that were always soluble? (never precipitated) Na+ Mg2+ Ni2+ Cr3+ Zn2+ Ag+ Pb2+ 2. Based on your answer to #1, use periodic trends to predict the solubility of: a. alkali metal ions

b. alkaline earth metal ions

(there’s no way we’d tackle the transition metals!) 3. Circle the anions that were always soluble.

- 2- - - - NO3 SO4 OH Cl I 4. Circle the anions that were seldom soluble.

- 2- - - - NO3 SO4 OH Cl I 5. Based on your answer to #3& 4, use periodic trends to predict the solubility of halogens ions.

- + - 6. Nitrate (NO3 ) is always soluble (all of its compounds), so is NH4 and CH3COO as well as the alkali metals (hint to #1). Halogens seem to be mostly insoluble.

If you have to predict solubility, which rule is more important? Why?

7. Does your answer to #6 explain all of the following chemical species?

AgCl AgI PbCl PbI NaCl Pb(NO3)2 AgNO3

3- 2- 2- 8. Go back to your list of insoluble (seldom soluble) compounds, add PO4 , CO3 , and S . 9. Predict if each of the following will be soluble. (Verbally discuss the why, pointing to solubility rules. Then put a check mark in the Why? box. Species Soluble? Why? Species? Soluble? Why?

KCl Pb(CH3COO)2

KNO3 CrPO4

Ca(OH)2 CaS