To determine which reaction yields a salt with the highest pH, we need to consider the nature of the acids and bases involved.
1. Strong acid + Strong base:
- Example: [tex]\(KOH + H_2SO_4\)[/tex]
- Salts formed from strong acids and strong bases are neutral salts, resulting in a pH close to 7.
2. Weak base + Strong acid:
- Example: [tex]\(NH_4OH + HCl\)[/tex]
- Salts formed from a weak base and a strong acid tend to be acidic, resulting in a pH less than 7.
3. Weak base + Strong acid:
- Example: [tex]\(Cu(OH)_2 + H_2SO_4\)[/tex]
- This also results in an acidic salt with a pH less than 7.
4. Strong base + Weak acid:
- Example: [tex]\(NaOH + CH_3COOH\)[/tex]
- Salts formed from a strong base and a weak acid tend to be basic, resulting in a pH greater than 7.
Thus, the salt with the highest pH will be formed from a reaction involving a strong base and a weak acid because the resulting salt will be basic.
Among the given options:
- [tex]\(KOH + H_2SO_4\)[/tex] involves a strong base and a strong acid.
- [tex]\(Cu(OH)_2 + H_2SO_4\)[/tex] involves a weak base and a strong acid.
- [tex]\(NH_4OH + HCl\)[/tex] involves a weak base and a strong acid.
- [tex]\(NaOH + CH_3COOH\)[/tex] involves a strong base and a weak acid.
Given this analysis, the reaction that yields a salt with the highest pH is:
[tex]\[ \boxed{NaOH + CH_3COOH} \][/tex]
