I need some help with making a solubility rule for CrO4 -2 for my chemistry homework.

it is insoluible with everyting except for NH4+, and the group one elements like: K, Na, Li, Rd, ect...

The oxyanion, CrO4 2- the chromate ion, is not in the solubility rules in our text. Examine your results from this lab and write a solubility rule CrO4 2-, the chromate ion. Cite experimental eidence to support your rule. This what our professor wants us to do.

http://www.files.chem.vt.edu/RVGS/ACT/notes/solubility_rules.html

Sure, I can help you with that!

To determine the solubility of a compound like CrO4^2- (chromate ion), we can use the solubility rules for ionic compounds.

To make a solubility rule for CrO4^2-, we need to look at its behavior in different chemical reactions and observe whether it tends to dissolve or precipitate.

One approach is to perform a series of reactions with different metal cations (positive ions) to see if a solid precipitate forms when they are mixed with CrO4^2-. If no precipitate forms, then we can conclude that the compound is soluble.

Here's a step-by-step method to make a solubility rule for CrO4^2-:

1. Start with a known soluble compound that contains CrO4^2-. For example, potassium chromate (K2CrO4) is a soluble salt.

2. Take a small amount of a solution of the chosen soluble compound (e.g., K2CrO4) in a test tube.

3. Add a small amount of a solution containing a different metal cation, such as silver nitrate (AgNO3) or lead nitrate (Pb(NO3)2).

4. Observe the reaction mixture. If a yellow or orange solid precipitates, it indicates that the compound is insoluble or slightly soluble in water. On the other hand, if no solid precipitate forms and the mixture remains clear, it suggests that the compound is soluble.

5. Repeat steps 3 and 4 with a few more metal cations, such as barium, calcium, zinc, or magnesium, to confirm the solubility behavior of CrO4^2-.

Based on the observations, you can form a solubility rule. For example:

Solubility Rule: Chromate compounds (CrO4^2-) are generally insoluble, except for alkali metal (Group 1) and ammonium metal salts.

Remember, this is just an example, and your observations might lead to slightly different conclusions. It's always important to base your solubility rule on experimental evidence.

I hope this helps you create a solubility rule for CrO4^2- in your chemistry homework!