Double Replacement Demo

Double Replacement Demo

Credit: American Chemical Society

Author: Yan Luo

This demonstration aims to illustrate the type of the double replacement reactions that can happen due to the formation of insoluable product (precipitation). All the reactions in this demonstration that have physical changes in this demonstration are due to formation of precipitates (no weak electrolyte or gas will be form).


To show that formation of precipitates is a type of double replacement reaction.

It can also be used to test students' ability to predict a reaction and their familiarity with the solubility rules. To do this, the teacher can let the students know what the reactants are before the experiment and ask the students to predict whether or not there will be any observable physical changes.

This demonstration can also be turned into a lab-competition. To do this, the instructor can let the students know the five types of solution for the lab without matching the names with the specific solution. A clean microplate (with ~12 wells) can be given to each pair or group of students with the expectation that the microplate not be washed before completion of the lab. The students would be asked to match the five solutions with their name tags and the pair of group of students that match all solutions solutions correctly using the minimum number of wells in the minimum amount of time will be the winner of the lab section.

No Description available
  • A spot plate of 6 or more wells
  • One dropper for each solution, five droppers in total

5 Types of solutions needed are described as following:

  • $0.1\text{M NaCl}$
  • $0.1\text{M CuSO}_4$
  • $0.1\text{M AgNO}_3$
  • $0.1\text{M Na}_3\text{PO}_4$
  • $0.1\text{M NaOH}$

Add the following two solutions into each watch-glass seperately:

  1. $0.1\text{M NaCl}$ and $0.1\text{M CuSO}_4$
  2. $0.1\text{M NaOH}$ and $0.1\text{M CuSO}_4$
  3. $0.1\text{M Na}_3\text{PO}_4$ and $0.1\text{M CuSO}_4$
  4. $0.1\text{M NaCl}$ and $0.1\text{M AgNO}_3$
  5. $0.1\text{M NaOH}$ and $0.1\text{M AgNO}_3$
  6. $0.1\text{M Na}_3\text{PO}_4$ and $0.1\text{M AgNO}_3$

No doulbe replacement reaction would happen due to formation of gas or weak electrolytes in this demonstration. All reactions would happen due to formation of precipitates and can be predicted by solubility rules

Chemcial Reactions demonstrated can be writeen as following:

  1. $\text{NaCl}_{(aq)} + \text{CuSO}_4_{(aq)} \to \text{No Reaction}$
  2. $2\text{NaOH}_{(aq)} + \text{CuSO}_4_{(aq)} \to \text{Na}_2\text{SO}_4_{(aq)} + \text{Cu(OH)}_2_{(s)}$
  3. $\text{Na}_3\text{PO}_4_{(aq)} + \text{CuSO}_4_{(aq)} \to \text{No Reaction}$
  4. $\text{NaCl}_{(aq)} + \text{AgNO}_3_{(aq)} \to \text{NaNO}_3_{(aq)} + \text{AgCl}_{(s)}$
  5. $\text{NaOH}_{(aq)} + \text{AgNO}_3_{(aq)} \to \text{NaNO}_3_{(aq)} + \text{AgOH}_{(s)}$
  6. $\text{Na}_3\text{PO}_4_{(aq)} + \text{AgNO}_3_{(aq)} \to 2\text{NaNO}_3_{(aq)} + \text{Ag}_3\text{PO}_4_{(s)} \text{(yellow)}$

Aqueous solutions should be neutralized before disposal

Solids should be disposed to solid waste container

Difficulty:Some laboratory experience required
Preparation Time:5 minutes Demonstration Time: 1 minutes
Availability of Materials:Not specified Cost of materials:$5
Last Updated:Tue 21 Jun 2011 15:37:23 EDT Viewed:159996 times viewed
Source:The Science House, North Carolina State University, The Science House