Lesson 7 Properties of Ionic and Molecular Compounds
Solubility of Ionic Compounds
Barium ions are toxic, yet are taken internally by patients to provide contrast for x-ray diagnosis of gastrointestinal problems. How is that possible?
B7.9 X-ray with barium contrast
Some ionic compounds are very soluble, which means they will dissolve in water to form aqueous solutions.
These substances will be identified with the state written as “(aq).” Other ionic compounds are only slightly soluble, which means that relatively few ions will dissolve in water. These compound states are written as “(s).” Doctors use barium
sulfate (BaSO4(s)) to provide the contrast for X-rays. Barium sulfate is only slightly soluble, and thus barium ions (the toxic part) remain bound in the compound and are not absorbed into the body.
Please note that the solubility table in your textbook is outdated. Only use the solubility table in your data booklet to answer questions in this course.
B7.10 Solubility table
Digging Deeper
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B7.10 Precipitate in a test tube
B7.10 Precipitate in a test tube
Understanding the solubility table will help you predict precipitates that will be formed during a chemical reaction.
Follow these steps to determine the solubility of an ionic compound:
- Identify if the cation is from group 1 or is the ammonium ion. If it is either, the compound will most likely be very soluble, (aq).
- If the compound does not contain a group 1 or ammonium cation, locate the anion across the top of the solubility table.
- Locate the cation in the column below the anion.
- If the cation is in the first row, the substance will be very soluble and form an aqueous solution, (aq).
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If the cation is in the second row, the substance will be slightly soluble and will be identified as having a solid state, (s).
Examples
Determine the solubility and the state for each of the following ionic compounds when they are placed in a beaker of water. Each example has a video to go with it. To play the video, click on the play icon next to the example.
Identify the cation. If it is from group 1 or is the ammonium ion, then the compound will most likely be very soluble and will be (aq).
Ba is not in group 1.
If the cation is not from group 1 nor is it the ammonium ion, then locate the anion across the top.
Locate the cation in the column below the anion. If it is in the first row, the substance will be very soluble, (aq); if it is in the second row, the substance will be slightly soluble, (s).
Watch this video to see a teacher work through this example. https://adlc.wistia.com/medias/in06sfv4t4
Identify the cation. If it is from group 1 or is the ammonium ion, then the compound will most likely be very soluble and will be (aq).
Li is in group 1.
Watch this video to see a teacher work through this example. https://adlc.wistia.com/medias/klor3z6cao
Identify the cation. If it is from group 1 or is the ammonium ion, then the compound will most likely be very soluble and will be (aq).
Fe is not in group 1.
If the cation is not from group 1 nor is it the ammonium ion, then locate the anion across the top.
Locate the cation in the column below the anion. If it is in the first row, the substance will be very soluble, (aq); if it is in the second row, the substance will be slightly soluble, (s).
Watch this video to see a teacher work through this example. https://adlc.wistia.com/medias/in06sfv4t4
Identify the cation. If it is from group 1 or is the ammonium ion, then the compound will most likely be very soluble and will be (aq).
Fe is not in group 1.
If the cation is not from group 1 nor is it the ammonium ion, then locate the anion across the top.
Locate the cation in the column below the anion. If it is in the first row, the substance will be very soluble, (aq); if it is in the second row the substance will be slightly soluble, (s).
Watch this video to see a teacher work through this example. https://adlc.wistia.com/medias/4x0aeej9ig
Identify the cation. If it is from group 1 or is the ammonium ion, then the compound will most likely be very soluble and will be (aq).
Ca is not in group 1.
If the cation is not from group 1 nor is it the ammonium ion, then locate the anion across the top.
Locate the cation in the column below the anion. If it is in the first row, the substance will be very soluble, (aq); if it is in the second row, the substance will be slightly soluble, (s).
Watch this video to see a teacher work through this example. https://adlc.wistia.com/medias/jw7lqmxh8h
Read This
Please read pages 57 and 58 in your Science 10 textbook. Please note that the solubility table in your textbook is outdated. Only use the solubility table in your data
booklet to answer questions in this course. Make sure you take notes on your readings to study from later. You should focus on using a solubility table to determine whether an ionic compound will be slightly soluble or very soluble. Remember, if you have
any questions or you do not understand something, ask your teacher! Practice Questions
Complete the following practice questions to check your understanding of the concept you just learned. Make sure you write complete answers to the practice
questions in your notes. After you have checked your answers, make corrections to your responses (where necessary) to study from.-
Identify if the following ionic compounds will be very soluble or slightly soluble in water.
Substance Solubility AgCl KMnO4 Cu3(PO4)2 CO(IO3)2
Substance Solubility AgCl slightly KMnO4 very Cu3(PO4)2 slightly CO(IO3)2 very - Identify the state (s or aq) for each of the following substances when they are placed in water.
Substance State K2Cr2O7 CrBr3 Al2(SO3)3 ZN(IO3)2
Substance State K2Cr2O7 (aq) CrBr3 (aq) Al2(SO3)3 (s) ZN(IO3)2 (s)