Basic Buffer Action
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Q. CH3NH2 (0.1 mole Kb = 5 ×10−4) is added to 0.08 mole of HCl and the solution is diluted to one litre, resulting hydrogen ion concentration is
- 5×10−5
- 1.6×10−11
- 8×10−11
- 8×10−2
Q. pH of resultant solution formed by mixing equal volumes of two solutions having pH=5.8 and pH=12.8 is
- 12.5
- 5.5
- 6.1
- 13.1
Q. Which will make a basic buffer?
- 50 mL of 0.1 M NaOH + 25 mL of 0.1 M CH3COOH
- 100 mL of 0.1 M CH3COOH + 100 mL of 0.1 M NaOH
- 100 mL of 0.1 M HCl + 200 mL of 0.1 M NH4OH
- 100 mL of 0.1 M HCl + 100 mL of 0.1 M NaOH
Q. Calculate the ratio of CH3NH2 to CH3NH+3Cl− required to create a buffer with pH = 10.14
Kb of CH3NH2=4.4×10−4
take log 2.27=0.356, log 0.313=−0.504
Kb of CH3NH2=4.4×10−4
take log 2.27=0.356, log 0.313=−0.504
- 0.5
- 0.31
- None of the above
- 1.05
Q. Basic buffer is made up of ?
- Weak base and Weak acid
- Weak base and its conjugate salt with strong acid
- Weak base and strong acid
- Strong base and its conjugate salt with weak acid
Q. Which will make basic buffer ?
- 100 mL of 0.1 M HCl+200 mL of 0.1M NH4OH
- 100 mL of 0.1 M CH3COOH+100 mL of 0.1 M NaOH
- 50 mL of 0.1M NaOH+25 mL of 0.1M CH3COOH
- 100 mL of 0.1 M HCl+100 mL of 0.1 M NaOH
Q. Calculate the weight in mg of HCl added to 100 ml of 0.1 N BOH to have its pH = 6.6 and Kb=6.25×10−8; Antilog (−7.4)=3.98×10−8. (Assume there is no change in volume on addition of HCl)
- 425
- 223
- 300
- 100
Q. Calculate the concentration of NH3 and NH+4Cl− present in the buffer solution of pH = 9, when total concentration of buffering reagents is 0.6 mol L−1. Take pKb for NH3=4.7, log 2=0.3
- [NH+4Cl−]=0.1M and [NH3]=0.3M
- [NH+4Cl−]=0.8M and [NH3]=0.2M
- [NH+4Cl−]=0.6M and [NH3]=0.6M
- [NH+4Cl−]=0.4M and [NH3]=0.2M
Q. Solution of 0.1 N NH4OH and 0.1 N NH4Cl has pH 9.25. pKb of NH4OH is :
- 9.25
- 4.75
- 3.75
- 8.25
Q. A 1 L aqueous solution is made by mixing NH4OH and HCl solution at 25∘C.
This can act as a basic buffer when :
This can act as a basic buffer when :
- Molar concentration of weak base is more than the molar concentration of strong acid i.e [NH4OH]>[HCl]
- Molar concentration of weak base is equal to the molar concentration of strong acid i.e [NH4OH]=[HCl]
- A basic buffer is always formed by NH4OH and HCl
- Molar concentration of weak base is less than the molar concentration of strong acid i.e [NH4OH]<[HCl]