Write the formula of conjugate acid of each of the following:
`S^(2-), CH_3NH_2 , NH_2^(-) , NH_3 , H_2PO_4^-`

Answer

To find the conjugate acid of each species, we need to remember that a conjugate acid is formed when a base accepts a proton (H⁺). Here’s how to determine the conjugate acids for the given species step by step:

1. **For S²⁻ (Sulfide Ion)**:
- **Step**: Accept a proton (H⁺).
- **Calculation**: S²⁻ + H⁺ → HS⁻
- **Conjugate Acid**: HS⁻ (Hydrosulfide Ion)

2. **For CH₃NH₂ (Methylamine)**:
- **Step**: Accept a proton (H⁺).
- **Calculation**: CH₃NH₂ + H⁺ → CH₃NH₃⁺
- **Conjugate Acid**: CH₃NH₃⁺ (Methylammonium Ion)

3. **For NH₂⁻ (Amide Ion)**:
- **Step**: Accept a proton (H⁺).
- **Calculation**: NH₂⁻ + H⁺ → NH₃
- **Conjugate Acid**: NH₃ (Ammonia)

4. **For NH₃ (Ammonia)**:
- **Step**: Accept a proton (H⁺).
- **Calculation**: NH₃ + H⁺ → NH₄⁺
- **Conjugate Acid**: NH₄⁺ (Ammonium Ion)

5. **For H₂PO₄⁻ (Dihydrogen Phosphate Ion)**:
- **Step**: Accept a proton (H⁺).
- **Calculation**: H₂PO₄⁻ + H⁺ → H₃PO₄
- **Conjugate Acid**: H₃PO₄ (Phosphoric Acid)

### Summary of Conjugate Acids:
- Conjugate acid of S²⁻: HS⁻
- Conjugate acid of CH₃NH₂: CH₃NH₃⁺
- Conjugate acid of NH₂⁻: NH₃
- Conjugate acid of NH₃: NH₄⁺
- Conjugate acid of H₂PO₄⁻: H₃PO₄