Question

practice problems - type ii chemical formulas
directions: write the correct formula for the compounds below.

1. iron (ii) chloride
2. copper (i) sulfide
3. lead (iv) iodide
4. tin (ii) fluoride
5. zinc bromide
6. tin (ii) oxide
7. chromium (iii) oxide
8. gold (i) iodide
9. manganese (ii) nitride
10. cobalt (iii) phosphide
11. iron (iii) chloride
12. copper (ii) sulfide
13. lead (ii) bromide
14. tin (iv) iodide
15. silver sulfide
16. tin (iv) oxide
17. manganese (iii) chloride
18. chromium (ii) nitride
19. gold (iii) oxide
20. cobalt (ii) phosphide
21. tin (ii) sulfide
22. silver bromide
23. gold (iii) bromide
24. manganese (ii) oxide
25. chromium (ii) chloride
26. lead (iv) nitride
27. cobalt (iii) oxide
28. copper (ii) iodide
29. tin (iv) fluoride
30. iron (ii) phosphide

Explanation:

Step1: Determine the ions

For each compound, identify the cation (metal ion with its charge indicated in Roman numerals) and the anion (non - metal or polyatomic ion). For example, in Iron (II) chloride:
- Cation: \(Fe^{2 +}\) (Iron with a + 2 charge)
- Anion: \(Cl^{-}\) (Chloride ion with a - 1 charge)

Step2: Use charge balance

The formula of an ionic compound is neutral. So, the sum of the positive and negative charges must be zero. For \(Fe^{2+}\) and \(Cl^{-}\):
Let the number of \(Fe^{2+}\) ions be \(x\) and \(Cl^{-}\) ions be \(y\). Then \(2x+( - 1)y = 0\). When \(x = 1\), \(y=2\). So the formula is \(FeCl_{2}\)

Step3: Generalize for other compounds

- **Copper (I) sulfide**: Cation \(Cu^{+}\), anion \(S^{2 -}\). Using charge balance \(+1x+( - 2)y = 0\), when \(x = 2,y = 1\). Formula \(Cu_{2}S\)
- **Lead (IV) iodide**: Cation \(Pb^{4+}\), anion \(I^{-}\). \(+4x+( - 1)y = 0\), when \(x = 1,y = 4\). Formula \(PbI_{4}\)
- **Tin (II) fluoride**: Cation \(Sn^{2+}\), anion \(F^{-}\). \(+2x+( - 1)y = 0\), when \(x = 1,y = 2\). Formula \(SnF_{2}\)
- **Zinc bromide**: Zinc (\(Zn^{2+}\)) and bromide (\(Br^{-}\)). \(+2x+( - 1)y = 0\), \(x = 1,y = 2\). Formula \(ZnBr_{2}\)
- **Tin (II) oxide**: \(Sn^{2+}\) and \(O^{2 -}\). \(+2x+( - 2)y = 0\), \(x = 1,y = 1\). Formula \(SnO\)
- **Chromium (III) oxide**: \(Cr^{3+}\) and \(O^{2 -}\). \(+3x+( - 2)y = 0\), when \(x = 2,y = 3\). Formula \(Cr_{2}O_{3}\)
- **Gold (I) iodide**: \(Au^{+}\) and \(I^{-}\). \(+1x+( - 1)y = 0\), \(x = 1,y = 1\). Formula \(AuI\)
- **Manganese (II) nitride**: \(Mn^{2+}\) and \(N^{3 -}\). \(+2x+( - 3)y = 0\), when \(x = 3,y = 2\). Formula \(Mn_{3}N_{2}\)
- **Cobalt (III) phosphide**: \(Co^{3+}\) and \(P^{3 -}\). \(+3x+( - 3)y = 0\), \(x = 1,y = 1\). Formula \(CoP\)
- **Iron (III) chloride**: \(Fe^{3+}\) and \(Cl^{-}\). \(+3x+( - 1)y = 0\), \(x = 1,y = 3\). Formula \(FeCl_{3}\)
- **Copper (II) sulfide**: \(Cu^{2+}\) and \(S^{2 -}\). \(+2x+( - 2)y = 0\), \(x = 1,y = 1\). Formula \(CuS\)
- **Lead (II) bromide**: \(Pb^{2+}\) and \(Br^{-}\). \(+2x+( - 1)y = 0\), \(x = 1,y = 2\). Formula \(PbBr_{2}\)
- **Tin (IV) iodide**: \(Sn^{4+}\) and \(I^{-}\). \(+4x+( - 1)y = 0\), \(x = 1,y = 4\). Formula \(SnI_{4}\)
- **Silver sulfide**: Silver (\(Ag^{+}\)) and \(S^{2 -}\). \(+1x+( - 2)y = 0\), \(x = 2,y = 1\). Formula \(Ag_{2}S\)
- **Tin (IV) oxide**: \(Sn^{4+}\) and \(O^{2 -}\). \(+4x+( - 2)y = 0\), \(x = 1,y = 2\). Formula \(SnO_{2}\)
- **Manganese (III) chloride**: \(Mn^{3+}\) and \(Cl^{-}\). \(+3x+( - 1)y = 0\), \(x = 1,y = 3\). Formula \(MnCl_{3}\)
- **Chromium (II) nitride**: \(Cr^{2+}\) and \(N^{3 -}\). \(+2x+( - 3)y = 0\), when \(x = 3,y = 2\). Formula \(Cr_{3}N_{2}\)
- **Gold (III) oxide**: \(Au^{3+}\) and \(O^{2 -}\). \(+3x+( - 2)y = 0\), when \(x = 2,y = 3\). Formula \(Au_{2}O_{3}\)
- **Cobalt (II) phosphide**: \(Co^{2+}\) and \(P^{3 -}\). \(+2x+( - 3)y = 0\), when \(x = 3,y = 2\). Formula \(Co_{3}P_{2}\)
- **Tin (II) sulfide**: \(Sn^{2+}\) and \(S^{2 -}\). \(+2x+( - 2)y = 0\), \(x = 1,y = 1\). Formula \(SnS\)
- **Silver bromide**: \(Ag^{+}\) and \(Br^{-}\). \(+1x+( - 1)y = 0\), \(x = 1,y = 1\). Formula \(AgBr\)
- **Gold (III) bromide**: \(Au^{3+}\) and \(Br^{-}\). \(+3x+( - 1)y = 0\), \(x = 1,y = 3\). Formula \(AuBr_{3}\)
- **Manganese (II) oxide**: \(Mn^{2+}\) and \(O^{2 -}\). \(+2x+( - 2)y = 0\), \(x = 1,y = 1\). Formula \(MnO\)
- **Chromium (II) chloride**: \(Cr^{2+}\) and \(Cl^{-}\). \(+2x+( - 1)y = 0\), \(x = 1,y = 2\). Formula \(CrCl_{2}\)
- **Lead (IV) nitride**: \(Pb^{4+}\) and \(N^{3 -}\). \(+4x+( - 3)y = 0\), when \(x = 3,y = 4\). Formula \(Pb_{3}N_{4}\)
- **Cobalt (III) oxide**: \(Co^{3+}\) and \(O^{2 -}\). \(+3x+( - 2)y = 0\), when \(x = 2,y = 3\). Formula \(Co_{2}O_{3}\)
- **Copper (II) iodide**: \(Cu^{2+}\) and \(I^{-}\). \(+2x+( - 1)y = 0\), \(x = 1,y = 2\). Formula \(CuI_{2}\)
- **Tin (IV) fluoride**: \(Sn^{4+}\) and \(F^{-}\). \(+4x+( - 1)y = 0\), \(x = 1,y = 4\). Formula \(SnF_{4}\)
- **Iron (II) phosphide**: \(Fe^{2+}\) and \(P^{3 -}\). \(+2x+( - 3)y = 0\), when \(x = 3,y = 2\). Formula \(Fe_{3}P_{2}\)

Answer:

1. \(FeCl_{2}\)
2. \(Cu_{2}S\)
3. \(PbI_{4}\)
4. \(SnF_{2}\)
5. \(ZnBr_{2}\)
6. \(SnO\)
7. \(Cr_{2}O_{3}\)
8. \(AuI\)
9. \(Mn_{3}N_{2}\)
10. \(CoP\)
11. \(FeCl_{3}\)
12. \(CuS\)
13. \(PbBr_{2}\)
14. \(SnI_{4}\)
15. \(Ag_{2}S\)
16. \(SnO_{2}\)
17. \(MnCl_{3}\)
18. \(Cr_{3}N_{2}\)
19. \(Au_{2}O_{3}\)
20. \(Co_{3}P_{2}\)
21. \(SnS\)
22. \(AgBr\)
23. \(AuBr_{3}\)
24. \(MnO\)
25. \(CrCl_{2}\)
26. \(Pb_{3}N_{4}\)
27. \(Co_{2}O_{3}\)
28. \(CuI_{2}\)
29. \(SnF_{4}\)
30. \(Fe_{3}P_{2}\)