[化學] 兩題化學問題！

[baskball399 (Dairy)]

1. For potassium, the enthalpy of sublimation is 89kJ/mol, and the first

   ionization energy is 419 kJ/mol. The bond dissociation energy of Br2(g)

   is 193kJ/,ol, and the electron affinity of bromine is -325 kJ/mol. The

   enthalpy of vaporization of Br2(l) is 31kJ/mol. The lattice energy of

   KBr is = 682kJ/mol. Calculate the overall enthapy change for the reaction:

   K(s) + 1/2Br2(l) → KBr(s)

   (A) +256  (B) -256  (C) -332  (D) -387  (E) -780



   註：Br2(l) → Br2(L) , 括弧內的是英文字母 L 不是數字 1 .


2. A chemist dissolves 1.00 mol of a monoprotice weak acid in 100.0 mL water

   and tutrates the resulting solution  with 0.025 M KOH. After 20.0 mL KOH

   has been added, the pH is 5.0. What is the ka value for the acid ?

   (A) 1.0x10 -4  (B) 1.0x10 -5  (C) 1.0x10 -6  (D) 1.0x10 -7



   註：選項中的1.0x10 -4 ，是負4。


   煩請各位大大幫忙解答一下，感謝:)

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※ 發信站: 批踢踢實業坊(ptt.cc) 
◆ From: 120.108.194.59
→ biup2:titrate?
→ biup2:[H+]= Na-Nb / Va+b           Na,Nb皆需乘以倍數
→ biup2:boom! i gave up
→ baskball399:抱歉，我明天再確認一次有沒有打錯！課本在圖書館@@..
→ baskball399:沒有打錯，除了/mol那邊之外@@"  麻煩大大解答了:)
→ baskball399:對不起，是titrate，後面才發現   ....