Which compound listed below has the greatest solubility in water?
CdCO3
Cd(OH)2
CaF2
AgI
ZnCO3
how can i tell which on to choose, no matter what compounds are listed?
To determine which compound has the greatest solubility in water, you can use the general solubility rules. Here are some guidelines to follow:
1. Solubility of Group 1 metals and ammonium compounds: Compounds containing Group 1 metals (such as Na+, K+, etc.) and ammonium (NH4+) ions are generally soluble in water.
2. Solubility of nitrate (NO3-), acetate (CH3COO-), and most perchlorate (ClO4-) compounds: These compounds are usually soluble in water.
3. Solubility of chloride (Cl-), bromide (Br-), and iodide (I-) compounds: Most chloride, bromide, and iodide compounds are soluble in water, with a few exceptions such as AgCl, PbCl2, and Hg2Cl2, which are insoluble.
4. Solubility of sulfate (SO42-), carbonate (CO32-), and phosphate (PO43-) compounds: Most sulfates are soluble (with exceptions like PbSO4, CaSO4), while most carbonates and phosphates are insoluble (with exceptions like group 1 metals and ammonium compounds).
Based on these guidelines, let's analyze the choices provided:
- CdCO3 is a carbonate compound. Generally, carbonates are insoluble, so the solubility of CdCO3 in water is expected to be low.
- Cd(OH)2 is a hydroxide compound. Although hydroxides are usually insoluble, Cd(OH)2 is an exception, and it has significant solubility in water.
- CaF2 is a fluoride compound. Most fluorides are insoluble, and CaF2 is not an exception. It has low solubility in water.
- AgI is an iodide compound. Based on the solubility guideline, most iodides are soluble, except for a few exceptions like AgI, which has low solubility in water.
- ZnCO3 is another carbonate compound. Like CdCO3, it is also generally insoluble, so its solubility in water is expected to be low.
Based on the general solubility rules, we can determine that Cd(OH)2 has the greatest solubility in water among the compounds listed.
To determine which compound has the greatest solubility in water, you need to consider a few factors. One of the main factors is the nature of the compound and its interactions with water molecules.
Generally, ionic compounds tend to be more soluble in water than covalent compounds. This is because the water molecules can surround and separate the individual ions, allowing them to dissolve. In contrast, covalent compounds often do not dissociate into ions and therefore may not dissolve easily in water.
Additionally, the charges on the ions in the compound also affect solubility. Compounds with ions that have higher charges tend to be more soluble because they have stronger attractions to water molecules.
To determine the compound with the greatest solubility in water from the list you provided (CdCO3, Cd(OH)2, CaF2, AgI, ZnCO3), we can consider the following:
1. CdCO3 and ZnCO3: Both of these compounds are similar because they contain metal cations (Cd2+ and Zn2+) and carbonate anions (CO32-). Since cadmium (Cd) has a higher atomic number than zinc (Zn), it forms stronger ionic attractions with the carbonate ion. Therefore, CdCO3 is expected to be more soluble in water than ZnCO3.
2. Cd(OH)2: This compound contains cadmium cations (Cd2+) and hydroxide anions (OH-). Hydroxide ions have a negative charge, and the two OH- ions in Cd(OH)2 give it a higher overall negative charge compared to carbonate (CO32-) ions in CdCO3. Consequently, Cd(OH)2 is expected to have greater solubility in water compared to CdCO3.
3. CaF2: Calcium fluoride consists of calcium cations (Ca2+) and fluoride anions (F-). Fluoride ions have a higher charge than the hydroxide ions in Cd(OH)2. Moreover, calcium ions have a higher charge than the cadmium ions in both Cd(OH)2 and CdCO3. Therefore, CaF2 is expected to have the highest solubility in water among the listed compounds.
4. AgI: Silver iodide contains silver cations (Ag+) and iodide anions (I-). Both silver and iodide ions have higher charges than the corresponding ions in Cd(OH)2, CdCO3, and CaF2. Thus, AgI is expected to have greater solubility in water compared to the other compounds listed.
In summary, in the given list, CaF2 is expected to have the greatest solubility in water, followed by AgI, Cd(OH)2, CdCO3, and ZnCO3, in that order. However, note that these predictions are based on general trends and assumptions and may vary in specific cases.
All of these are insoluble compounds. You look up the Ksp of each and calculate the solubility from the Ksp you find. One very important note here: The question doesn't specify units for solubility so you may get different answers if you calculate solubility in moles/L versus grams/L.
YOU MEMORIZE the solubility rules. Make some flash cards, and get it done.
http://www.flashcardexchange.com/tag/solubility