Question

use the following table to answer the question.

strong acids	weak acids	weak bases	strong bases
hcl	hf	nh₄oh	koh
h₂so₄	hcn	cu(oh)₂	ca(oh)₂

which reaction yields a salt with the highest ph?

• ( \boldsymbol{koh + h_2so_4} )
• ( \boldsymbol{cu(oh)_2 + h_2so_4} )
• ( \boldsymbol{nh_4oh + hcl} )
• ( \boldsymbol{naoh + ch_3cooh} )

Explanation:

1. Recall the nature of salts formed from acid - base reactions:

• For a reaction between a strong acid (\( SA \)) and a strong base (\( SB \)): The salt formed is neutral, so \( pH = 7 \). For example, in the reaction \( KOH(\text{strong base})+H_2SO_4(\text{strong acid})\), the salt \( K_2SO_4 \) is neutral.
• For a reaction between a strong acid (\( SA \)) and a weak base (\( WB \)): The salt formed is acidic, so \( pH<7 \). For example, in the reaction \( NH_4OH(\text{weak base}) + HCl(\text{strong acid})\), the salt \( NH_4Cl \) is acidic.
• For a reaction between a weak acid (\( WA \)) and a strong base (\( SB \)): The salt formed is basic, so \( pH > 7 \).
• For a reaction between a weak acid (\( WA \)) and a weak base (\( WB \)): The \( pH \) of the salt depends on the relative strengths of the acid and base. For example, in the reaction \( Cu(OH)_2(\text{weak base})+H_2SO_4(\text{strong acid})\), the salt \( CuSO_4 \) is acidic (since strong acid and weak base react).

1. Analyze each option:

• Option 1: \( KOH + H_2SO_4 \): \( KOH \) is a strong base, \( H_2SO_4 \) is a strong acid. The salt \( K_2SO_4 \) is neutral (\( pH = 7 \)).
• Option 2: \( Cu(OH)_2+H_2SO_4 \): \( Cu(OH)_2 \) is a weak base, \( H_2SO_4 \) is a strong acid. The salt \( CuSO_4 \) is acidic (\( pH<7 \)).
• Option 3: \( NH_4OH + HCl \): \( NH_4OH \) is a weak base, \( HCl \) is a strong acid. The salt \( NH_4Cl \) is acidic (\( pH<7 \)).
• Option 4: \( NaOH+CH_3COOH \): \( NaOH \) is a strong base, \( CH_3COOH \) is a weak acid. The salt \( CH_3COONa \) is basic (\( pH > 7 \)). Among the options, the salt formed from a weak acid and a strong base will have the highest \( pH \) (since basic salts have \( pH>7 \) and acidic/neutral salts have \( pH\leq7 \)). So the reaction \( NaOH + CH_3COOH \) yields a salt with the highest \( pH \).

Answer:

D. \( NaOH + CH_3COOH \)