• 2022-07-23
    欲配制pH=3的缓冲溶液,应选用
    A: HCOOH-HCOONa(pKa,HCOOH=3.77)
    B: HAc-NaAc(pKa,HAc=4.75)
    C: NaH2PO4-Na2HPO4(pKa,H2PO4-=7.21)
    D: NH4Cl-NH3(pKa,NH4+=9.25)
    E: NH4Ac-HAc(pH=5)
  • A

    内容

    • 0

      现要配制pH=4.5的缓冲溶液,最理想的缓冲对是()。 A: ANaH<sub>2</sub>PO<sub>4</sub>-Na<sub>2</sub>HPO<sub>4</sub>(pK(H<sub>2</sub>PO<sub>4<sup><sup>-</sup>)=7.21)</sup></sub> B: BHAc-NaAc(pK(HAc)=4.76) C: CHCOOH-HCOONa(pK(HCOOH)=3.75) D: DNH<sub>3</sub>-NH<sub>4</sub>Cl(pK(NH<sub>3</sub>)=4.75)

    • 1

      配制pH=9.0的缓冲溶液,应选用哪对缓冲对 A: NH4Cl—NH3·H2O (pKb=4.75) B: HCOOH—HCOONa (pKa=3.5) C: H2PO4-—HPO42-(pKa =7.21) D: HAc—Ac- (pKa =4.75)

    • 2

      配制pH=9.0的缓冲溶液,应选用哪对缓冲对 A: HCOOH—HCOONa (pKa=3.5) B: HAc—Ac- (pKa =4.75) C: NH4Cl—NH3·H2O (pKb=4.75) D: H2PO4-—HPO42-(pKa =7.21)

    • 3

      欲配制pH=10的缓冲溶液,应选用( )缓冲对。‌ A: HCOOH-HCOONa [pKa⊙(HCOOH) = 3.75] B: HAc-NaAc [pKa⊙(HAc) = 4.74] C: NaH2PO4- Na2HPO4 [pKa2⊙(H3 PO4) = 7.21] D: NH3-NH4Cl [pKb⊙(NH3) = 4.75]

    • 4

      欲配置pH=10的缓冲溶液,最好应选择的缓冲对是 A: HAc-NaAc[pKa(HAc)=4.75] B: NH3-NH4Cl[pKb(NH3)=4.75] C: HCOOH-HCOONa [pKa (HCOOH)=3.75] D: NaH2PO4-Na2HPO4 [pKa2(H3PO4)=7.2]