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Choose the correct statement (s) out ...

Choose the correct statement (s) out of the following

A

In `CH_(3)COOH //CH_(3)COONa ` buffer , the reserve acjdity of the solution is due to `CH_(3)COO^(-)` ions

B

It is not necessary that an acidic substance must contain hydrogen ions

C

`HCO_(3)^(-)` is both Bronsted base and Bronsted acid

D

Sodium carbonate does not contain `OH^(-)` ions and thus is not a base

Text Solution

AI Generated Solution

The correct Answer is:
To solve the question, we need to evaluate each statement provided and determine whether it is correct or incorrect. Let's analyze each option step by step. ### Step 1: Evaluate the First Statement **Statement:** In sodium acetate buffer (CH3COONa), acetic acid (CH3COOH) is a weak acid which, after giving H⁺, gives a conjugate base (CH3COO⁻). **Analysis:** - Acetic acid (CH3COOH) is indeed a weak acid. - When it donates a proton (H⁺), it forms its conjugate base, acetate ion (CH3COO⁻). - The acetate ion can hydrolyze in solution, which contributes to the buffer's ability to resist changes in pH. **Conclusion:** This statement is correct. ### Step 2: Evaluate the Second Statement **Statement:** It is not necessary that an acidic substance must contain hydrogen. **Analysis:** - The example of boric acid (B(OH)3) is provided, which does not contain ionizable hydrogen but can still act as an acid by accepting hydroxide ions (OH⁻) and releasing H⁺ into the solution. - This shows that acidity can be defined by the ability to accept protons rather than the presence of hydrogen atoms. **Conclusion:** This statement is correct. ### Step 3: Evaluate the Third Statement **Statement:** HCO3⁻ is both a Brønsted base and a Brønsted acid. **Analysis:** - HCO3⁻ (bicarbonate ion) can accept a proton (acting as a Brønsted base) to form H2CO3 (carbonic acid). - It can also donate a proton (acting as a Brønsted acid) to form CO3²⁻ (carbonate ion). - This dual behavior confirms that HCO3⁻ can act as both an acid and a base. **Conclusion:** This statement is correct. ### Step 4: Evaluate the Fourth Statement **Statement:** Sodium carbonate (Na2CO3) does not contain OH⁻ ions, thus does not act as a base. **Analysis:** - Sodium carbonate dissociates in solution to form Na⁺ ions and CO3²⁻ ions. - CO3²⁻ comes from carbonic acid (H2CO3), which is a weak acid. Therefore, CO3²⁻ can act as a base by accepting protons (H⁺). - Even though Na2CO3 does not contain OH⁻ ions, it can still act as a base due to the presence of CO3²⁻ ions. **Conclusion:** This statement is incorrect. ### Final Conclusion The correct statements are: 1. First statement is correct. 2. Second statement is correct. 3. Third statement is correct. 4. Fourth statement is incorrect. ### Summary of Correct Statements: - The correct statements are the first, second, and third options. ---
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