本次日本代写主要为化学相关的assignment

1. 加入 (a) 10 ml, (b) 1ml 和 (c) 0.1ml 己烷制备三种己烷水溶液
分别为 1 升水。水和己烷之间的界面张力在室温下为 40 mN/m
温度。
(1) 根据自由能描述每种溶液(混合或分离)的平衡状态
正己烷被分成 N 个液滴。
(2)向溶液(b)中逐渐加入表面活性剂。当表面活性剂的浓度
超过一定值,溶液变浑浊。分子长度和堆积参数
表面活性剂的波长分别为 10 nm 和 0.2。假设所有的表面活性剂分子都是
吸附在水-己烷界面,计算表面活性剂的阈值浓度,以上
可以观察到光散射。

2、表中为苯酚溶液在30摄氏度时的表面张力。计算表面
苯酚分子在 0.100 wt% 溶液中的吸附。您可以使用吉布斯吸附等温线
方程。
苯酚浓度(wt%) 0.024 0.047 0.118 0.471
表面张力 (mN/m) 72.6 72.2 71.3 66.5

3.假设你要混合液体A和B。在混合过程中,总体积保持不变,
并且不会发生化学反应。考虑两种情况并回答问题。
(A) 在 � 参数由 � ൌ 500/� 给出的情况下(T 是开尔文温度):
(1) 计算临界点 �௖ ,高于该临界点,溶液独立于
混合比例。
(2) 描述共存成分在 273 K 时的体积分数。
(3) 给出 273 K 处的旋节线上的体积分数。

1. Three aqueous solutions of hexane are prepared by adding (a) 10 ml, (b) 1ml and (c) 0.1ml of hexane
to 1 liter of water, respectively. The interfacial tension between water and hexane is 40 mN/m at room
temperature.
(1) Describe the equilibrium state of each solution (mixed or separated), based on the free energy when
the hexane is divided into N droplets.
(2) To the solution (b), a surfactant was gradually added. When the concentration of the surfactant
exceeded a certain value, the solution became turbid. The molecular length and the packing parameter
of the surfactant are 10 nm and 0.2, respectively. Assuming that all the surfactant molecules are
adsorbed on the water-hexane interface, calculate the threshold concentration of the surfactant, above
which the light scattering can be observed.

2. The table shows the surface tension of phenol solutions at 30 degrees Celsius. Calculate the surface
adsorption of phenol molecules in 0.100 wt% solution. You can use Gibbs adsorption isotherm
equation.
Concentration of phenol (wt%) 0.024 0.047 0.118 0.471
Surface tension (mN/m) 72.6 72.2 71.3 66.5

3. Suppose that you will mix liquids A and B. In the mixing process, the total volume is maintained,
and no chemical reactions take place. Consider the two cases and answer the questions.
(A) In the case that �-parameter is given by � ൌ 500/� (T is the temperature in kelvin):
(1) Calculate the critical point �௖ , above which the solution is uniformly mixed independently of
mixing ratios.
(2) Describe the volume fraction of the coexisting compositions at 273 K.
(3) Give the volume fraction on the spinodal line at 273 K.


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