Question

for the following compounds, give the cation and anion with their charges and name the compound.
table 6. ions in ionic compounds. (4 points each)

1. na₂hpo₄
2. mgcl₂
3. mno₃
4. cr₂o₃
5. al(ch₃coo)₃
6. (nh₄)₂so₄
7. kcn

for the following compounds, give the correct formula. (2 points each)

1. cobalt(ii) hydroxide
2. dichlorine trioxide
3. barium phosphide
4. arsenic pentafluoride
5. iron(iii) sulfide

Explanation:

1. \(Na_2HPO_4\)

• Cation: \(Na^+\) (sodium ion with +1 charge). Sodium is in group 1 of the periodic table and typically loses one electron to form \(Na^+\).
• Anion: \(HPO_4^{2 - }\) (hydrogen phosphate ion with -2 charge).
• Compound Name: Disodium hydrogen phosphate.

2. \(MgCl_2\)

• Cation: \(Mg^{2+}\) (magnesium ion with +2 charge). Magnesium is in group 2 of the periodic table and loses two electrons.
• Anion: \(Cl^-\) (chloride ion with -1 charge).
• Compound Name: Magnesium chloride.

3. \(MnO_3\)

• Cation: \(Mn^{6+}\) (manganese ion with +6 charge). Let the charge of \(Mn\) be \(x\). In \(MnO_3\), using the rule that the sum of charges in a neutral compound is zero (\(x+3\times(- 2)=0\), so \(x = +6\)).
• Anion: \(O^{2 - }\) (oxide ion with -2 charge).
• Compound Name: Manganese(VI) oxide.

4. \(Cr_2O_3\)

• Cation: \(Cr^{3+}\) (chromium ion with +3 charge). Let the charge of \(Cr\) be \(y\). In \(Cr_2O_3\), \(2y+3\times(-2)=0\), so \(y = +3\)).
• Anion: \(O^{2 - }\) (oxide ion with -2 charge).
• Compound Name: Chromium(III) oxide.

5. \(Al(CH_3COO)_3\)

• Cation: \(Al^{3+}\) (aluminum ion with +3 charge). Aluminum is in group 13 and loses three electrons.
• Anion: \(CH_3COO^-\) (acetate ion with -1 charge).
• Compound Name: Aluminum acetate.

6. \((NH_4)_2SO_4\)

• Cation: \(NH_4^+\) (ammonium ion with +1 charge).
• Anion: \(SO_4^{2 - }\) (sulfate ion with -2 charge).
• Compound Name: Ammonium sulfate.

7. \(KCN\)

• Cation: \(K^+\) (potassium ion with +1 charge). Potassium is in group 1 and loses one electron.
• Anion: \(CN^-\) (cyanide ion with -1 charge).
• Compound Name: Potassium cyanide.

Formula Part

1. Cobalt(II) hydroxide

• Cobalt has a charge of \(+2\) (\(Co^{2+}\)) and hydroxide is \(OH^-\). Using the criss - cross method (charges become sub - scripts), the formula is \(Co(OH)_2\).

2. Barium phosphide

• Barium has a charge of \(+2\) (\(Ba^{2+}\)) and phosphide is \(P^{3 - }\). Using the criss - cross method, the formula is \(Ba_3P_2\).

3. Iron(III) sulfide

• Iron has a charge of \(+3\) (\(Fe^{3+}\)) and sulfide is \(S^{2 - }\). Using the criss - cross method, the formula is \(Fe_2S_3\).

4. Dichlorine trioxide

• “Di -” means 2 (for chlorine, \(Cl\)) and “tri -” means 3 (for oxygen, \(O\)). The formula is \(Cl_2O_3\).

5. Arsenic pentafluoride

• “Penta -” means 5 (for fluorine, \(F\)) and arsenic is \(As\). The formula is \(AsF_5\).

Answer:

Compound	Cation	Anion	Compound Name
\(MgCl_2\)	\(Mg^{2+}\)	\(Cl^-\)	Magnesium chloride
\(MnO_3\)	\(Mn^{6+}\)	\(O^{2 - }\)	Manganese(VI) oxide
\(Cr_2O_3\)	\(Cr^{3+}\)	\(O^{2 - }\)	Chromium(III) oxide
\(Al(CH_3COO)_3\)	\(Al^{3+}\)	\(CH_3COO^-\)	Aluminum acetate
\((NH_4)_2SO_4\)	\(NH_4^+\)	\(SO_4^{2 - }\)	Ammonium sulfate
\(KCN\)	\(K^+\)	\(CN^-\)	Potassium cyanide

1. \(Co(OH)_2\)
2. \(Ba_3P_2\)
3. \(Fe_2S_3\)
4. \(Cl_2O_3\)
5. \(AsF_5\)