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Topic: Buffer Solution CH3COOH  (Read 19503 times)

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Beetle

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Buffer Solution CH3COOH
« on: June 15, 2005, 12:23:40 AM »
What Volume of 0.25M NaOH soln must be added to 125mL of 0.44M CH3COOH solution to give a buffer solution with a pH of 5.40 (Ka CH3COOH = 1.75e-5)

I tried using the buffer solution
pH = pKa + log([A-]/[HA])
and got to
4.3958 = ([A-]/[HA])

but i cant work out where to go from there

Any hints would be wonderful!
Thanx

Offline AWK

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Re:Buffer Solution CH3COOH
« Reply #1 on: June 15, 2005, 02:39:42 AM »
write down a neuralization reaction
[A-] = moles_of_NaOH/final_Volume
[HA] = (moles_of_CH3COOH - moles_of_NaOH)/final_Volume
moles_of_CH3COOH = moles_of_A- + moles of_HA

Hence you have a system of equations of type
x/y = A
x+y = B
AWK

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