CuS, Ag2SO4, Al(ClO3)3, Co(OH)2, PbCO3.

Question

1A.

Give the names of the cation in each of the following compounds: CuS , Ag2SO4 , Al(ClO3)3 , Co(OH)2 , PbCO3 .

 

2A.

Give the charges of the cation in each of the following compounds: CuS , Ag2SO4 , Al(ClO3)3 , Co(OH)2 , PbCO3 .

 

3A.

Give the names of the anion in each of the following compounds: CuS , Ag2SO4 , Al(ClO3)3 , Co(OH)2 , PbCO3 .

 

4A.

Give the charges of the anion in each of the following compounds: CuS , Ag2SO4 , Al(ClO3)3 , Co(OH)2 , PbCO3 .

Answer 1

Latika,

 

The thing to remember here is that anions are negatively charged ions while cations are positively charged. You can determine their charges based on how many of the other ion is required to stabilize it. The names are a matter of memorization. So let's tackle these in that order.

CuS. anion: S. cation: Cu. anion charge is -2 (second from right on periodic table). cation charge is therefore 2+. Name is copper sulfide. Why not sulfur? Because Sulfur creates lots of ions with fancy names. Sulfite is S03. Sulfate is S04. S02 happens to be stable and poisons the earth as sulfur dioxide.

 

Ag2SO4. anion: S04. cation: Ag. anion charge is -2. cation charge is therefore +1 because it takes two Ag to stabilize this compound. Name is Silver Sulfate. (look above for my list of sulfur ions)

 

Al(ClO3)3. anion: Cl03. cation: Al. anion charge: -1. cation charge is therefore +3. Name is Aluminum chlorate. Like sulfur, chlorine likes to form different ions with different names. By itself, we call it chloride. ClO2 is chlorine dioxide. Cl04 is perchlorate!

 

Co(OH)2. anion: OH. cation: Co. anion charge: -1 (This is good to remember). cation charge: +2. Name is Cobalt hydroxide. (OH is a useful ion to memorize in general).

 

PbCO3. anion: CO3. cation: Pb. anion charge: -2. cation charge: +2. The name is Lead Carbonate. C03 is a generally a useful ion to memorize when you see carbon and oxygen reacting.  Others include CO (carbon monoxide), CO2 (carbon dioxide) and CO4 (carbon tetroxide). I remember carbonate by the role it plays in baking soda (sodium bicarbonate or NaHCO3).

 

Hope that helps!

 

Answer 2

Hi Lakita,

 

This particular problem is asking you to identify cations and anions in various compounds.  A cation is a positively-charged species, while an anion is a negatively-charged species.  In many cases, we can determine the charge by looking at the element's placement on the periodic table (i.e. Group IA elements have a +1 charge, Group VIIA elements have a -1 charge).  Here are the answers to help you out:

 

1A. You are asked to name the cations.  Transition metals must contain a Roman numeral.

 

copper (II), silver (I), aluminum, cobalt (II), lead (II)

 

1B. You are asked to identify the charge of the cation.  For the transition metals, it's as easy as looking at the Roman numeral from 1A.

 

Cu⁺², Ag⁺¹, Al⁺³, Co⁺², Pb⁺²

 

1C. You now need to name the anions.  With the exception of the first example, all others are polyatomic ions.

 

sulfide, sulfate, chlorate, hydroxide, carbonate

 

1D. Finally, you must identify the charges for these anions.

 

S^-2, SO₄^-2, ClO₃^-1, OH^-1, CO₃^-2

 

Again, I hope this helps!