Which of the following mixtures act(s) as a buffer solution?
- NaOH+CH3COOH (1:1 mole ratio)
- NH4OH+HCl (2:1 mole ratio)
- CH3COOH+NaOH (2:1 mole ratio)
- CH3COOH+NaOH (1:2 mole ratio)
The Correct Option is B, C
Solution and Explanation
Buffer Concept Recap:
An acidic buffer contains a weak acid + its salt with a strong base (e.g., CH₃COOH + CH₃COONa).
A basic buffer contains a weak base + its salt with a strong acid (e.g., NH₄OH + NH₄Cl).
Let’s analyze the options:
- (A) NaOH + HCOONa:
Not a buffer. It contains a strong base (NaOH) and the salt of a weak acid (HCOONa), but lacks the weak acid itself (formic acid). Hence, not a buffer system. - (B) NH₄OH + HCl in 2:1 mole ratio:
When NH₄OH (a weak base) reacts with HCl (a strong acid), NH₄Cl is formed. In a 2:1 mole ratio, there will be unreacted NH₄OH and formed NH₄Cl, making a basic buffer.
Correct. - (C) CH₃COOH + NaOH in 2:1 mole ratio:
CH₃COOH is a weak acid, NaOH is a strong base. In a 2:1 mole ratio, some CH₃COOH reacts to form CH₃COONa (the salt), and leftover CH₃COOH remains. This creates an acidic buffer.
Correct. - (D) NaOH + HCOONa (repeated from A):
Still not a buffer.
Correct answer: (B) and (C)
Top Questions on Equilibrium
- Which of the following statements is/are true about equilibrium?
- KCET - 2025
- Chemistry
- Equilibrium
Consider the following equilibrium, $$ \text{CO(g)} + \text{H}_2\text{(g)} \rightleftharpoons \text{CH}_3\text{OH(g)} $$ 0.1 mol of CO along with a catalyst is present in a 2 dm$^3$ flask maintained at 500 K. Hydrogen is introduced into the flask until the pressure is 5 bar and 0.04 mol of CH$_3$OH is formed. The $ K_p $ is ...... x $ 10^7 $ (nearest integer).
Given: $ R = 0.08 \, \text{dm}^3 \, \text{bar} \, \text{K}^{-1} \, \text{mol}^{-1} $
Assume only methanol is formed as the product and the system follows ideal gas behavior.- JEE Main - 2025
- Chemistry
- Equilibrium
The pH of a 0.01 M weak acid $\mathrm{HX}\left(\mathrm{K}_{\mathrm{a}}=4 \times 10^{-10}\right)$ is found to be 5 . Now the acid solution is diluted with excess of water so that the pH of the solution changes to 6 . The new concentration of the diluted weak acid is given as $\mathrm{x} \times 10^{-4} \mathrm{M}$. The value of x is _______ (nearest integer).
- JEE Main - 2025
- Chemistry
- Equilibrium
A body of mass $m$ is suspended by two strings making angles $\theta_{1}$ and $\theta_{2}$ with the horizontal ceiling with tensions $\mathrm{T}_{1}$ and $\mathrm{T}_{2}$ simultaneously. $\mathrm{T}_{1}$ and $\mathrm{T}_{2}$ are related by $\mathrm{T}_{1}=\sqrt{3} \mathrm{~T}_{2}$. the angles $\theta_{1}$ and $\theta_{2}$ are
- JEE Main - 2025
- Physics
- Equilibrium
- According to Le Chatelier's principle, in the reaction \( \text{CO}(g) + 3\text{H}_2(g) \rightleftharpoons \text{CH}_4(g) + \text{H}_2\text{O}(g) \), the formation of methane is favoured by
- KCET - 2025
- Chemistry
- Equilibrium
Questions Asked in WBJEE exam
- Let \( f(\theta) = \begin{vmatrix} 1 & \cos \theta & -1 \\ -\sin \theta & 1 & -\cos \theta \\ -1 & \sin \theta & 1 \end{vmatrix} \). Suppose \( A \) and \( B \) are respectively the maximum and minimum values of \( f(\theta) \). Then \( (A, B) \) is equal to:
- If \( a, b, c \) are in A.P. and if the equations \( (b - c)x^2 + (c - a)x + (a - b) = 0 \) and \( 2(c + a)x^2 + (b + c)x = 0 \) have a common root, then
- WBJEE - 2025
- Quadratic Equations
- If \( g(f(x)) = |\sin x| \) and \( f(g(x)) = (\sin \sqrt{x})^2 \), then:
- WBJEE - 2025
- Functions
- Which logic gate is represented by the following combination of logic gates?
- WBJEE - 2025
- Logic gates
- Ruma reached the metro station and found that the escalator was not working. She walked up the stationary escalator with velocity \( v_1 \) in time \( t_1 \). On another day, if she remains stationary on the escalator moving with velocity \( v_2 \), the escalator takes her up in time \( t_2 \). The time taken by her to walk up with velocity \( v_1 \) on the moving escalator will be:
- WBJEE - 2025
- Relative Motion
Concepts Used:
Buffer solutions
The buffer solution is a solution that is able to maintain its Hydrogen ion concentration (pH) with only minor changes on the dilution or addition of a small amount of either acid or base. They are used in fermentation, food preservatives, drug delivery, printing, the activity of enzymes and many more.
Buffer solutions are aqueous solutions containing a weak acid and its salt - acid buffer or a weak base and its salt - base buffer.
Types of Buffer Solution
Acidic Buffers
These solutions are used to maintain acidic environments. Also, it has acidic pH and is prepared by mixing a weak acid and its salt with a strong base. An aqueous solution of an equal concentration of acetic acid and sodium acetate has a pH of 4.74.
Alkaline Buffers
These solutions are used to maintain basic conditions. It has a basic pH and is prepared by mixing a weak base and its salt with strong acid. The aqueous solution of an equal concentration of ammonium hydroxide and ammonium chloride has a pH of 9.25.