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which mixture forms a buffer when dissolved in 1L of water? a)0.2 mol NaOH+ 0.2 mol HBr b)0.2 mol Nacl+ 0.3 molHCL c)0.4 mol HNO2+ 0.2 mol NaOH d)0.5 mol NH3+ 0.5 molHCL please explain each option

which mixture forms a buffer when dissolved in 1L of water?
a)0.2 mol NaOH+ 0.2 mol HBr
b)0.2 mol Nacl+ 0.3 molHCL
c)0.4 mol HNO2+ 0.2 mol NaOH
d)0.5 mol NH3+ 0.5 molHCL

please explain each option

Grade:11

1 Answers

Aman Bansal
592 Points
12 years ago

Dear Parth,

a) will not form a buffer because it is a mixture of a strong base and a strong acid.

b) will not form a buffer because it is a mixture of a neutral salt and a strong acid.

c) will form a buffer because it is a mixture of a weak acid and its conjugate base. 0.2 mol of NaOH will neutralize 0.2 mol of HNO2; you'll be left with 0.2 mol of HNO2 and 0.2 mol of NaNO2 (or, more specifically, NO2^-). The pH will be equal to the pKa of HNO2.

d) would have formed a buffer if you had added less HCl; however, you're adding so much HCl that it completely protonates NH3 to NH4+. You'll be left with 0.5 mol of NH4+ and 0.5 mol of Cl-.

Best Of luck

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Thanks

Aman Bansal

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