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Home Q & A Board Science-Related Homework Help Chemistry (Moderator: Laser_3)
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fierdous fierdous
wrote...
11 years ago
I need to how to find the concentration of NaNO2 that is necessary to buffer .05 M HNO2. (Ka= 4x10^-4) at pH=3.00.
I was thinking that i need to find the conentration of H ions but idk what to do after that.
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wrote...
#1
11 years ago
pKa = - log Ka = 3.40
The Hasselbalch's equation is :
pH = pKa + log [salt] / [acid]

3.00 = 3.40 + log [NO2-] / 0.05

- 0.40 = log [NO2-] / 0.05

10^-0.40 = [NO2-] / 0.06
0.398 = [NO2-] / 0.06

[NO2-] = 0.0239 M
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