Double Replacement - Solid Formed

ChemistryWiki | RecentChanges | Preferences

The direction to determine if a double replacement reaction occurs via formation of a solid is as follows:

Remember: In double replacement reaction, you simply switch one set of ions so that each ion is combining with a new ion (switch dance partners) to form the potential products

Click here for Solubility table, Solubility Table.

1. With the correct chemical formula of the potential products, look for the anion in the first potential product. Determine its chemical name and then look on the Solubility Table for the appropriate row where the anion name matches the name from the first column of the row.

2. Determine the correct chemical name of the cation. Most anions will have two rows, each with a separate set of cations or the words, all other (second column).

3. Once you determine the correct row (from the second column), go to the third column. There will be two words, soluble or low solubility. Soluble = aqueous and Low solubility = solid.

4. Now you know the phase of that potential product. Repeat for the other potential product.

5. As stated above, if one of these potential products are solid, then the reaction occurs. If neither potential products is a solid, the reaction will not occur.

Example
Ca1Cl2 (aq) + Na2(SO4)1 (aq) -->

First potential product: Ca2+ and SO42-.
Step 1: SO42- is sulfate, so find on Solubility Table in 1st Column.
Step 2: Then go to row that has Ca2+, cation, in the 2nd Column.
Step 3: Then go to the 3rd Column and you see it says Low Solubility. This means it forms a solid.
Step 4: Since it forms a solid product, the reaction occurs and this product is Ca1(SO4)1 (s)

2nd potential product: Na1+ and Cl1-.
Step 1: Cl1- is chloride, so find on Solubility Table in 1st Column.
Step 2: Then go to row that has Na1+, cation, in the 2nd Column. Here, there is no column that says it but it is one of the all others.
Step 3: Then go to the 3rd Column and you see it says Soluble. This means it is aqueous.
Step 4: This product is Na1Cl1 (aq)

Step 5: So the overall reaction that does occur (since one of products is a solid) is:

Ca1Cl2 (aq) + Na2(SO4)1 (aq) --> Ca1(SO4)1 (s) + Na1Cl1 (aq)

You then have to balance it, which is another story.


ChemistryWiki | RecentChanges | Preferences
Edit text of this page | View other revisions
Last edited February 28, 2017 8:14 am (diff)
Search: