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Predicting Precipitates (12 Favorites)

LAB in Chemical Change, Precipitate, Balancing Equations, Chemical Change, Chemistry Basics, Solubility Rules, Reactions & Stoichiometry. Last updated October 1, 2018.


Summary

In this lab, students use solubility rules to predict which chemical reactions will produce precipitates. They then test their predictions using spot tests.

Grade Level

Middle or high school

Objectives

By the end of this lesson, students should be able to

  • use solubility rules to predict which chemical reactions will produce precipitates.
  • determine which product from each reaction will precipitate.

Chemistry Topics

This lesson supports students’ understanding of

  • Reactions
  • Solutions
  • Precipitates
  • Balancing equations
  • Solubility rules

Time

Teacher Preparation: 1 hour to make solution bottles

Lesson: 40 minutes for each spot test concluding reflection

Materials

For each group:

  • 2 spot trays
  • 2 water rinse bottles
  • 1 waste bucket
  • Goggles
  • Paper towels
  • 1-M solutions of each of the following compounds:
    • AgNO3
    • Pb(NO3) 2
    • CaCl2
    • KI
    • NaCl
    • NaOH
    • FeCl3
    • NaSO4
    • NaI
    • Na2CO3
    • CuSO4

Safety

  • Always wear safety goggles when working with chemicals in a laboratory setting.
  • When working with bases and other chemicals in this experiment, if any solution gets on students’ skin, they should immediately alert you and thoroughly flush their skin with water.
  • Students should wash their hands thoroughly before leaving the lab.
  • When students complete the lab, instruct them how to clean up their materials and dispose of any chemicals.

Teacher Notes

  • Before beginning the lab, make sure students understand where each chemical should be placed in each well plate.
  • It may be helpful to check students’ chemical equations before having them perform the spot tests.

For the Student

Lesson

Purpose

To investigate and predict which compounds will form precipitates in a reaction.

Safety

Always wear safety goggles when working with chemicals in a laboratory setting.

Materials

  • 2 spot trays
  • 2 water rinse bottles
  • 1 waste bucket
  • Goggles
  • Paper towels
  • 1-M solutions of each of the compounds listed in Table 1.

Procedure

Part I: Making Predictions

  1. Record the correct formula for each chemical compound in Table 1.
  2. Record the color of each chemical compound in Table 1.
  3. Record safety hazards from MSDS book for each chemical compound in Table 1.
Table 1: Chemical Safety
COMPOUNDS
FORMULA
COLOR
SAFETY HAZARDS (Use MSDS book)
Silver Nitrate
Lead(II) Nitrate
Calcium Chloride
Potassium Iodide
Sodium Chloride
Sodium Hydroxide
Iron(III) Chloride
Sodium Sulfate
Sodium Iodide
Sodium Carbonate
Copper(II) Sulfate
  1. Predict below which reactions in each spot test will form precipitates based on the precipitate rules we learned. In the charts below, put an “X” in the square of reactions you think will form precipitates based on your solubility chart.
Spot Test 1:
KI NaCl NaOH FeCl3
AgNO3
Pb(NO3)2
CaCl2
Spot Test 2:
Na2SO4 NaI Na2CO3 CuSO4
AgNO3
Pb(NO3)2
CaCl2

Part II: Completing the Equations

  1. Complete the product side of the equations for the each of the reactions below.
  2. Balance each chemical equation.
  3. Circle the compound in the products that you think will be the precipitate (if any).

REACTANTS PRODUCTS
AgNO3 + KI ----->
AgNO3 + NaCl ----->
AgNO3 + NaOH ----->
AgNO3 + FeCl3 ----->
Pb(NO3)2 + KI ----->
Pb(NO3)2 + NaCl ----->
Pb(NO3)2 + NaOH ----->
Pb(NO3)2 + FeCl3 ----->
CaCl2 + KI ----->
CaCl2 + NaCl ----->
CaCl2 + NaOH ----->
CaCl2 + FeCl3 ----->
  1. Complete the product side of the equations for the each of the reactions below.
  2. Balance each chemical equation.
  3. Circle the compound in the products that you think will be the precipitate (if any).

REACTANTS PRODUCTS
AgNO3 + Na2SO4 ----->
AgNO3 + NaI ----->
AgNO3 + Na2CO3 ----->
AgNO3 + CuSO4 ----->
Pb(NO3)2 + Na2SO4 ----->
Pb(NO3)2 + NaI ----->
Pb(NO3)2 + Na2CO3 ----->
Pb(NO3)2 + CuSO4 ----->
CaCl2 + Na2SO4 ----->
CaCl2 + NaI ----->
CaCl2 + Na2CO3 ----->
CaCl2 + CuSO4 ----->

Part III: Spot Testing Experiment

SPOT TEST #1:

  1. Put two (2) drops of each of the solutions listed on top in the first row of wells.
  2. Add one (1) drop of AgNO3 to each of the same wells.
  3. In chart below, Record “Yes Precip” or “No Precip” and if “Yes”, record the color of precipitate also.
  4. Repeat with second row and adding (1) drop of Pb(NO3)2 to each well in second row.
  5. Repeat with second row and adding (1) drop of CaCl2 to each well in second row.
KI NaCl NaOH FeCl3
AgNO3
Pb(NO3)2
CaCl2

Spot Test #2:

  1. Rinse the spot plate with water bottle into the waste bucket. Dry with paper towel.
  2. Put two (2) drops of each of the solutions listed on top in the first row of wells.
  3. Add one (1) drop of AgNO3 to each of the same wells.
  4. In chart below, RECORD “Yes Precip” or “No Precip” and if “Yes”, record the color of precipitate also.
  5. Repeat with second row and adding (1) drop of Pb(NO3)2 to each well in second row.
  6. Repeat with second row and adding (1) drop of CaCl2 to each well in second row.
Na2SO4 NaI Na2CO3 CuSO4
AgNO3
Pb(NO3)2
CaCl2

Conclusion

Record your conclusion paragraph below. Were your predictions correct? If not, why do you think the compounds did not follow the solubility rules?