AP化学真题讲解 考点赶紧拿这几道题来练练手吧

即将迎来AP大考，同学们有把握拿到理想分吗？今天给大家整理了几道AP化学真题，赶紧在考前看看同学们有没有拿理想分的可能吧！

AP化学真题

(a) For nonpolar CS2 molecule, there is London dispersion force; for polar COS molecule, there are London dispersion force and dipole-dipole force. Since CS2 has a larger molecular mass and more electrons than COS, CS2 has a stronger London dispersion force than the combination of London dispersion force and dipole-dipole force in COS. Therefore, CS2 has a higher boiling point than COS.

(b) PV = nRT

P = nRT / V = 10.0g x (1mol/76.13g) x 0.08206 L atm mol-1 K-1 x 325K / 5.0L = 0.70 atm

(a) Since percent ionization of HF is 13.0%, most particles containing F should be in the form of unionized form HF at equilibrium, which means that HF is a weak acid and only partially ionized in water. Figure 1 shows partial ionization of HF. In figure 2, all HF molecules are completely ionized into H3O+ and F-, which corresponds to a strong acid.

(c) The percent ionization of HF in the solution will increase. When the solution is diluted, the concentration of the “particles” in the solution is reduced. According to Le Chatelier’s principle, this reduction in particle concentration is counteracted by shifting the reaction to the side with more particles.The equilibrium shifts from the nonionized acid side to the side containing the H+ ion and the conjugate base. The percent ionization of the acid increases.

(a) The missing component of the cell is salt bridge. It allows electrical contact between the two solutions and the cell can form a closed circuit.

这道题考察考生离子方程式的书写，要求能够识别反应前后不变的离子，要求可以识别反应后形成的沉淀物质是什么，继而将离子方程式配平。

题中给出排水法收集气体的装置图，考查分析实验数据的能力，此外还涉及有热力学与路易斯结构式的考查。大约有1%的考生获得满分（10分），对于该题考生的平均分为3.88。易犯错误：Part(a)：注意P total=PC2H2+PH2O,很多考生容易忽略水的蒸气压,并且注意运用PV＝nRT时，先转换为标准单位。凡是涉及计算的考题留心有效数字的保留。Part(b)：不要混淆percent yield和percent error，注意区分上问中计算出的actual yield和theoretical yield。Part(c)：注意建立ΔGo与平衡常数的关系，ΔGo＝－RTlnK。Part(d)：注意不要漏掉氧原子剩余的孤对电子。Part(e)：判断键角的度数需要先判断分子空间构型，由于C－O－H为bent（与水分子类似），只要给出的度数在100°－115°之间都不扣分。Part(f)：注意从分子间作用力的不同展开讨论，必须提到氢键以及伦敦色散力以及与在水中溶解度的关系（相似相溶原理）。

化学是一门偏重于记忆的国际课程。如果你记忆力好，又对化学感兴趣，那么你在化学考试上的优势非常大。如果你记忆力不好也没关系，找对方法一样可以考的很好，橡沐为了应对5月大考，特地推出了AP精品课程班。

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