A buffer solution containing H2CO3 and NaHCO3 is to be prepared to maintain a pH of 7.00. What must be the ratio NaHCO3 in order to realize such a pH if Ka of carbonic HCO3 acid is 4.3 x 10^7?
Correct answer: D. 4.3
- A. 43
- B. 48
- C. 0.43
- D. 4.3
Explanation
pH=pKa+ Log NaHCO3/H2CO3 7=4.3*10^-7+ Log NaHCO3/H2CO3 Log NaHCO3/H2CO3=7 NaHCO3/H2CO3=10^7 NaHCO3=10^7* H2C03 NaHCO3=10^7*4.3^-7 NaHCO3=4.3
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About Buffer Solutions
Buffer solutions resist changes in pH when small amounts of acid or base are added, using a weak acid and its conjugate base or a weak base and its conjugate acid. Work includes buffer action, the common-ion effect, Henderson-Hasselbalch calculations, buffer capacity, and the difference between acidic and basic buffers.
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