JEE Main Chemistry question
What is the sum of the "magic numbers" of all solutions given below? (Integer value is between 50 and 60.) Magic number = pH of solution × Weight factor.
| Solution | Weight factor | |---|---| | I. 0.1 M HCN (Kₐ=10⁻¹⁰) | 2 | | II. 0.1 M CH₃COOH + 0.1 M CH₃COONa (Kₐ=10⁻⁵) | 1 | | III. 0.1 M HCl | 3 | | IV. 0.01 M NH₄OH =10⁻⁵) | 2 | | V. 0.01 M NaOH | 0.5 | | VI. 10 mL of 0.01 M CH₃COOH + 10 mL of 0.1 M NH₄OH | 1 |
Answer: 56
Solution
I: [H⁺]=√(10⁻¹⁰×0.1)=3.16×10⁻⁶, pH=5.5, magic no.=11. II (buffer, equal conc.): pH=pKa=5, magic no.=5. III: pH=1, magic no.=3. IV: [OH⁻]=√(10⁻⁵×0.01)=3.16×10⁻⁴, pOH=3.5, pH=10.5, magic no.=21. V: pOH=2, pH=12, magic
See the full step-by-step solution
Create a free account to read the complete working, and practise questions like this in a timed test.
Create a free account