请教2道题

zasdzccUID: 173579

A solution can be both (A) dilute and concentrated (B) saturated and dilute (C) saturated and unsaturated (D)  supersaturated and saturated.
Answer:(B) ABCD都像答案为何选B

A foam is an example of (A) a gas dispersed in a liquid (B) a liquid dispersed in a gas
Answer:A
B也有可能为什么不对？
thanks.

事实UID: 163475

(A) dilute and concentrated 又稀又浓
(B) saturated and dilute 又稀又饱和 这个可以
(C) saturated and unsaturated 又饱和又不饱和
(D)  supersaturated and saturated 又饱和又过饱和

明显B only

事实UID: 163475

(A) a gas dispersed in a liquid (B) a liquid dispersed in a gas

这俩应该一个是泡沫一个是雾滴 还是不一样的吧。
就看foam定义的是哪个了。anyway记下来就是。

so猫UID: 148633

谢谢事实的解答~~~

不过想请问一下楼主 这个是化学题 还是物理题?

zasdzccUID: 173579

化学题

so猫UID: 148633

化学居然有这样的题 变态
再想请问一下楼主
楼主的资料是电子版的吗
如果是电子版的
可以上传上来给大家分享吗
提前谢谢

zasdzccUID: 173579

是BARRON'S PREPARATION

zasdzccUID: 173579

1.Zinc electrode is anode and copper electrode is cathode.
这句话是不是应该这样：Zinc electrode is cathode and copper electrode is anode.?

2.Electrode potential are
Zn=(Zn2+) +2e  E0=0.76V
Au=(Au3+) +3e E0=-1.42V
If a gold foil were placed in a solution containing zinc ions,the reacations potential      
would be :(A)-1.34 (B)-2.18 (C) -0.66 (D) +2.18 (E) +1.34
Answer:B
为何不是这样算这道题：(n1*E1+n2*E2)/(n1+n2) 来算?
Thanks.

so猫UID: 148633

1.Zinc electrode is anode and copper electrode is cathode.
这句话是不是应该这样：Zinc electrode is cathode and copper electrode is anode.?

原电池吗?
锌负阳极 铜正阴极
英文里面 阳极是anode 阳离子是cation
阴极是cathode 阴离子是anion
题目是对的

2.Electrode potential are
Zn=(Zn2+) +2e  E0=0.76V
Au=(Au3+) +3e E0=-1.42V
If a gold foil were placed in a solution containing zinc ions,the reacations potential      
would be A)-1.34 (B)-2.18 (C) -0.66 (D) +2.18 (E) +1.34
Answer:B
为何不是这样算这道题：(n1*E1+n2*E2)/(n1+n2) 来算?
Thanks.

你这是想用gibbs自由能来算吧?
但是在算原电池的电势差的时候是不能这样算的
标准电极电势都是对SHE来说的
你给的公式是在谈到G=-nEF在计算带能量的时候才能用的
我自己都说糊涂了
去看一下你的物理化学书 里面肯定有定义的~~~

zasdzccUID: 173579

如果是Zinc electrode is anode and copper electrode is cathode.那么就应该是电解池
但是书上画的是原电池.
是不是anode 指电解池的阳极（失电子）也指原电池的负极（失电子）？
Thanks.

so猫UID: 148633

Originally posted by zasdzcc at 2005-5-17 21:51
如果是Zinc electrode is anode and copper electrode is cathode.那么就应该是电解池
但是书上画的是原电池.
是不是anode 指电解池的阳极（失电子）也指原电池的负极（失电子）？
Thanks.

正确
判断阳极的标准是看该处的半反应是否是氧化反应 也就是你说的失电子
跟电子流向无关

zasdzccUID: 173579

During the seperation of a mixture by chromatography,there
should be a slit on the aluminum foil.
请问为何要在aluminum foil 上有slit才可分离mixture?
Thanks.

zasdzccUID: 173579

When excited electron cascade to lower energy levels in an atom,
(A) visible light is always emitted
(B) the potential energy of the atom increases
(C) the electron always fall back to the first energy level
(D) the electron fall discriminately to all levels.
(E) the electron fall back to the lowest unfilled energy level
Answer(E).
请问为何选E不选A？electron cascade是甚么.Thanks.

so猫UID: 148633

Originally posted by zasdzcc at 2005-5-19 16:40
When excited electron cascade to lower energy levels in an atom,
(A) visible light is always emitted
(B) the potential energy of the atom increases
(C) the electron always fall back to the firs ...

electron cascade
电子跃迁

zasdzccUID: 173579

What is the apparent oxidation number of the nitrogen element
in the compound.
NH3
Answer:+3
I choose -3.
The electronegativities of the nitrogen and hydrogen are
respectively 3.04 and 2.02.Why the nitrogen's oxidation number is +3?Not -3?
I choose -3.