The chart shown below is from the Chemistry STAAR resource materials. It is one way to represent the solubility of common ions. Remember, these are only for compounds dissolved in water. If the solvent was changed, so were all the rules.

Think back to the lab you saw in the video in the previous section. Compare your results to the predicted solubility of compounds in this chart.

For example, all NH₄₊ ions were soluble. What does the chart say about the solubility of NH₄₊ ions?

• NH₄₊ is listed under the column “Soluble compounds contain.”
• There are no ions listed next to NH₄₊ in the column “Common Exceptions.”
• This means that all common compounds containing NH₄₊ are soluble, just like you saw in the video.

Let’s try one more example. Ag₂CO₃ formed an insoluble compound, but (NH₄)₂CO₃ was soluble. Does the solubility chart accurately predict those results?

• CO₃^-2 is listed in the column “Insoluble compounds contain,” so it is expected that most compounds that contain the carbonate ion are insoluble.
• However, there are several ions listed in the column “Common exceptions” next to CO₃^-2. NH₄₊ is listed as a common exception.
• Therefore, it is expected that (NH₄)₂CO₃ is soluble and that Ag₂CO₃ is insoluble, as seen in the lab.

As you read the chart, remember the following:

1. Break compounds up into their ions.
2. Search for each ion separately and pay attention to which column the ion is in.
3. Alkali metals are Group 1 metals.

Now it is your turn to practice using the solubility chart on your own.