A solution is 0.30 m in nh3. what concentration of nh4cl would be required to achieve a buffer solution with a final ph of 9.0? recall the hh equation can be written using ph and pka or poh and pkb. the kb of nh3 is 1.8 x 10-5.

Question

Amy Curtis

Chemistry

13 September, 01:51

A solution is 0.30 m in nh3. what concentration of nh4cl would be required to achieve a buffer solution with a final ph of 9.0? recall the hh equation can be written using ph and pka or poh and pkb. the kb of nh3 is 1.8 x 10-5.

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Answers (1)

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Coleman Horn · Answer 1

- first, we have to get POH.

and when we have PH = 9 so,

PH+POH = 14

POH = 14 - 9 = 5

- then by using this formula of PKa:

PKa = - ㏒Kb and when we have Kb = 1.8x10^-5 so by substitution:

PKa = - ㏒ 1.8x10^-5

∴PKa = 4.7

So know we have Pka & POH So by substitution in the following formula w can get the concentration:

POH = Pka + ㏒[HB]/[B}

5 = 4.7 + ㏒[HB]/[0.3]

∴[HB] (NH4Cl) = 0.599 m