水夜 asked in 科學化學 · 1 decade ago

普通化學3題,高手來喔

1.

What volume of 0.200M HCl will react completely with 50.00ml of

0.100M NaOH?

(A) 100ml (B) 50ml (C) 25ml (D) 12.5ml

2.

Which of the following reaction is spontaneous?

(A) Cu2+ + Fe -----> Cu + Fe2+ (B) Zn2+ + Cu-----> Zn + Cu2+

(C) 2Al3+ + 3Fe -----> 2Al + 3Fe2+ (D) none of the above

3.

Which one of the following descriptions on the buffered solutions,

OH- + HA -----> A- +H2O , is incorrect?

(A) A buffered solution is one that gives a change in pH when wither

hydroxide ions or protons are removed.

(B) A buffered solution with a constant pH for blood is vital,because

cells can survive only in a very narrow pH range.

(C) Buffered solutions are simply solutions of weak acideor base

containing a common ion.

(D) The net result of buffering is that the equilibrium concentration

H+ and thus the pH are determined by the ratio [HA]/[A-]

(For a weak acid HA and its conjugate base A-)

第3題我看不太懂,麻煩解釋一下喔

1 Answer

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  • sky
    Lv 4
    1 decade ago
    Favorite Answer

    1.

    強酸與強鹼的中和反應,考慮HCl與NaOH產生的質子與氫氧根 離子的莫耳數需相等

    50.00ml of 0.100M NaOH , 氫氧根離子=0.1*0.05=0.005mol

    故需 0.200M HCl 0.005/0.2*1000=25ml

    2.離子氧化還原的自發反應,僅要看 氧化電位大的元素發生氧化

    反應成陽離子,氧化電位小的元素發生還原反應成陰離子

    (A) Cu2 Fe -----> Cu Fe2

    Cu → Cu2 2e- 氧化電位 -0.34

    Fe → Fe2 2e- 氧化電位 0.44

    故鐵氧化電位高氧化成Fe2 ,銅氧化電位低還原成Cu,為自發反應,BC也依此法,為非自發反應

    有關氧化還原電位請參考

    http://www.siliconfareast.com/ox_potential.htm

    3.

    A錯

    A buffer solution has the property that the pH of the solution changes very little when a small amount of acid or base is added to it.

    B對

    Buffer solutions are necessary to keep the correct pH for enzymes in many organisms to work. Many enzymes work only under very precise conditions

    C對

    buffer solution is an aqueous solution consisting of a mixture of a weak acid and its conjugate base or a weak base and its conjugate acid.

    D對

    The acid dissociation constant for a weak acid,Simple manipulation with logarithms gives the Henderson-Hasselbalch equation, which describes pH in terms of pKa

    請參考

    http://en.wikipedia.org/wiki/Buffer_solution#Commo...

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