Microscale Chemical Reactions –
Solubility
Introduction:
Today we will perform twenty-eight chemical reactions! Not bad for one lab
period. While exploring the reaction of several combinations of chemicals we will
generate less than 20 milliliters of chemical waste per student.
We will practice writing balanced chemical equations for each reaction that we
perform to represent double replacement (aka metathesis) reactions and we will
use this information to devise a set of solubility rules.
Learning Objectives:
(a) Observe a reaction mixture and distinguish between soluble and insoluble
compounds.
(b) Learn to classify compounds as soluble and insoluble.
(c) Learn to balance chemical reactions of salts.
Materials:
-0.1 M solutions of eleven different salts in dropper bottles or with droppers
-Sheet protector
-Reaction grid
-Safety goggles
Hazard Information:
Solution
Health Hazards
Physical Hazards
0.1 M AlCl3 0.1 M KCl 0.1 M NH4Cl 0.1 M MgCl₂ 0.1 M CaCl2 0.1 M FeCl₃ 0.1 M SrCl2 0.1 M NaBr 0.1 M Na2CO3 0.1 M Na2SO4 0.1 M Na₃PO₄ Irritant Irritant Low hazard Irritant Low hazard Irritant Irritant Low hazard Irritant Low hazard Low hazard Mildly corrosive Low hazard Low hazard Low hazard Low hazard Mildly corrosive Low hazard Low hazard Low hazard Low hazard Low hazard Siena Green Chemistry Summer Institute Lucas Tucker, Ann Klotz V2 Environmental
Hazards
Low hazard Low hazard Low hazard Low hazard Low hazard Low hazard Low hazard Low hazard Low hazard Low hazard Low hazard Page 1 Waste:
Description of
Material
Quantity
per
group
0.1 M Salt solution 3 mL
mixture
Sheet Protector
1
Hazard Disposal Method
Low
Low
Curl the reaction sheet and allow the
drops to drain into a beaker.
Trash
Procedure:
1. Obtain an 8 1/2" x 11" plastic pouch and a laminated paper grid. The grid will
look like the Data Collection Table for this experiment. The plastic sheet will
serve as the reaction vessel for all of your reactions simultaneously. Slip the grid
sheet into the pocket of the plastic sheet protector. Wipe the plastic sheet
carefully with a dry towel to remove any residue from previous experiments.
Tape the plastic sheet down flat on the bench.
2. A box containing small dropper bottles of solutions will be provided for each
pair of students. All the starting materials are soluble, so a precipitate in the
reactant bottle indicates that the bottle is contaminated with some other
substance. If any of the bottles contains a precipitate or cloudiness, show it
to your instructor and the bottle will be replaced.
3. Place a drop of each cation on the grid. Start with the potassium chloride
solution and working your way across with one drop in each box. Continue to the
next row of boxes and put a drop of ammonium chloride solution in each of the
boxes in the next row. Continue until there is a drop of cation in each box.
4. Add a drop of anion solution next to, not on top of, the drop of cation, starting
with bromide ion. Be careful not to touch the drop on the sheet with the tip of
the dropper! Add anions down each column until the there is a drop of anion
and a drop of cation in each box.
5. Use a toothpick to nudge the pairs of drops together and then stir with the
same end of the toothpick. Use the fresh toothpick for each reaction.
6. Record your observations for each reaction in the table below. What is the
color of the starting solutions? What is the color of the reacted solution? Is there
a precipitate? What color is the precipitate?
Cleanup:
Remove the tape. Carefully curl the plastic sheet, and empty as much as possible of
the solutions and solids into a large beaker. Pour the contents of the beaker into the
labeled waste container.
Siena Green Chemistry Summer Institute Lucas Tucker, Ann Klotz V2 Page 2 Student Name:___________________
Date: ___________________
Observations
Data Summary
Fill in the following table with the data gathered from the experiment. Look for the
formation of solid precipitate, color change and gas bubbles.
Na+
→-
↓
Cl-
Br-
CO32-
SO42-
PO43-
Al3+
NH4+
Ca2+
3+
Fe
K+
Mg2+
Sr2+
Siena Green Chemistry Summer Institute Lucas Tucker, Ann Klotz V2 Page 3 Lab Questions
1) Which cations seemed to be soluble when mixed with any of the anions and
which seemed to be insoluble?
Soluble
Insoluble
2) Which anions seemed to be soluble when mixed with any of the cations and
which seemed to be insoluble?
Soluble
Insoluble
3) Green Question(s)
List three ways that running these reactions on microscale makes this lab
greener.
References
Siena College Chemistry Department Lab book. Solubility Rules. Written in fall
2004.
Siena Green Chemistry Summer Institute Lucas Tucker, Ann Klotz V2 Page 4 TEACHER INFORMATION
Solution preparation
Chemical Name
Molecular
Weight
To prepare 100 mL of
0.1M solution
KCl
NH4Cl
MgCl₂.6H₂O
CaCl2
AlCl3. 6H₂O
FeCl₃·6H₂O
SrCl·6H₂O
NaBr
Na2CO3
Na2SO4
Na₃PO₄·12H₂O
74.55
Grams/m
53.49
ole
203.3
110.98
241.43
270.3
266.62
102.89
105.99
142.04
380.12
0.74
0.53
2.03
1.10
2.41
2.70
2.66
1.02
1.05
1.42
3.80
Data Summary ↓ →
Cl
Al
3+
Br
-
CO3
2-
SO4
2-
PO4
3-
No precipitate Precipitate +
No precipitate No precipitate No precipitate No Precipitate 2+
No precipitate Precipitate Precipitate Precipitate 3+
No precipitate Precipitate No precipitate Precipitate No precipitate Precipitate No precipitate Precipitate No precipitate Precipitate No precipitate No precipitate No precipitate Precipitate Precipitate Precipitate Mg
+
Sr
+
Precipitate Ca
K
Na
No precipitate NH4
Fe
-
+
2+
Siena Green Chemistry Summer Institute Lucas Tucker, Ann Klotz V2 Page 5 Balanced Chemical reactions that form precipitates:
2 AlCl3 (aq) + 3 Na2CO3 (aq) è Al2(CO3)3 (s) + 6 Na+ (aq) + 6 Cl- (aq)
AlCl3 (aq) + Na3PO4 (aq) è AlPO4 (s) + 3 Na+(aq) + 3 Cl-(aq)
2 KCl (aq) + Na2CO3 (aq) è K2CO3 (s) + 2 Na+(aq) + 2 Cl-(aq)
MgCl2 (aq) + Na2 CO3 (aq) è MgCO3 (s) +2 Na+(aq) + 2 Cl-(aq)
3 MgCl2(aq) + 2 Na3PO4(aq) è Mg3(PO4)2 + 6 Na+(aq) + 6 Cl-(aq)
CaCl2 (aq) + Na2 CO3(aq) è CaCO3(s) + 2 Na+(aq) + 2 Cl-(aq)
CaCl2 (aq) + Na2SO4(aq) è CaSO4 (s) + 2 Na+(aq) + 2 Cl-(aq)
3CaCl2(aq) + 2 Na3PO4(aq) è Ca3(PO4)2 (s) + 6 Na+(aq) + 6 Cl-(aq)
2 SrCl2(aq) + Na2CO3(aq) è Sr2CO3(s) + 2 Na+(aq) + 2 Cl-(aq)
SrCl2(aq) + Na2SO4(aq) è SrSO4 (s) + 2 Na+(aq) + 4 Cl-(aq)
3 SrCl2(aq) + 2Na3PO4(aq) è Sr3(PO4)2 (s) + 6 Na+(aq) + 6 Cl-(aq)
2 FeCl3(aq) + 2 Na2 CO3(aq) è Fe2(CO3)2 (s) + 4 Na+(aq) + 6 Cl-(aq)
FeCl3(aq) + Na3PO4(aq) è FePO4 (s) + 3 Na+(aq) + 3 Cl-(aq)
1) Which cations seemed to be soluble when mixed with any of the anions and
which seemed to be insoluble?
Soluble: Na+, NH4+
Insoluble: None
2) Which anions seemed to be soluble when mixed with any of the cations and
which seemed to be insoluble?
Soluble : Cl-, BrInsoluble : None
Green Question
3 List three ways that running these reactions on microscale makes this lab
greener.
1) Reduces the volume of material created
2) Reduces the volume of waste material
3) Reduces the amount of salt that must be created.
Siena Green Chemistry Summer Institute Lucas Tucker, Ann Klotz V2 Page 6 MICROSCAL SOLUBILITY
Reaction Grid
Na+ ↓ →-­‐ Br-­‐ I-­‐ CO32-­‐ SO42-­‐ PO43-­‐ Cl-­‐ Al3+ NH4+ Ca2 Fe3+ K+ Mg2+ Sr+ Siena Green Chemistry Summer Institute Lucas Tucker, Ann Klotz V2 Page 7 Which of the 12 principles of Green Chemistry were employed to make this lab
greener? VPrevention It’s better to prevent waste than to treat or clean up waste
afterwards.
mAtom Economy Design synthetic methods to maximize the incorporation of
all materials used in the process into the final product.
VLess Hazardous Chemical Syntheses Design synthetic methods to use and
generate substances that minimize toxicity to human health and the
environment.
VDesigning Safer Chemicals Design chemical products to affect their
desired function while minimizing their toxicity.
mSafer Solvents and Auxiliaries Minimize the use of auxiliary substances
wherever possible make them innocuous when used.
mDesign for Energy Efficiency Minimize the energy requirements of
chemical processes and conduct synthetic methods at ambient temperature
and pressure if possible.
mUse of Renewable Feedstock’s Use renewable raw material or feedstock
rather whenever practicable.
mReduce Derivatives Minimize or avoid unnecessary derivatization if possible,
which requires additional reagents and generate waste.
mCatalysis Catalytic reagents are superior to stoichiometric reagents.
mDesign for Degradation Design chemical products so they break down into
innocuous products that do not persist in the environment.
mReal-time Analysis for Pollution Prevention Develop analytical
methodologies needed to allow for real-time, in-process monitoring and control
prior to the formation of hazardous substances.
mInherently Safer Chemistry for Accident Prevention Choose substances
and the form of a substance used in a chemical process to minimize the
potential for chemical accidents, including releases, explosions, and fires.1
EPA: Twelve Principles of Green Chemistry. Retrieved from http://www.epa.gov/sciencematters/june2011/principles.htm
Siena Green Chemistry Summer Institute Lucas Tucker, Ann Klotz V2 Page 8