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Question
The hydrogen ion concentration of a buffer solution consisting of a weak acid and its salts is given by ____________.
Options
`["H"^+] = "K"_"a"(["acid"])/(["salt"])`
[H+] = Ka [salt]
[H+] = Ka [acid]
`["H"^+] = "K"_"a"(["salt"])/(["acid"])`
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Solution
The hydrogen ion concentration of a buffer solution consisting of a weak acid and its salts is given by `underline(["H"^+] = "K"_"a"(["acid"])/(["salt"]))`.
Explanation:
According to Henderson equation
pH = `"pK"_"a" + log (["salt"])/(["acid"])`
i.e., −log [H+] = `-log "K"_"a" + log (["salt"])/(["acid"])`
−log [H+] = `log (["salt"])/(["acid"]) xx 1/("K"_"a")`
`log 1/(["H"^+]) = log (["salt"])/(["acid"]) xx 1/("K"_"a")`
∴ [H+] = `"K"_"a"(["acid"])/(["salt"])`
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