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楼主 |
发表于 24-5-2009 10:27 PM
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发表于 24-5-2009 10:31 PM
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那还好，我lower的时候也是blur blur的。
乘你现在lower，你最好去搞懂+完全掌握form4最前的那几课，尤其是那些molar的。
form6很重要。 |
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楼主 |
发表于 24-5-2009 10:32 PM
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If the ratio of Cl-35 to Cl-37 is 3:1,calculate the percentage abundance of the peaks.
想问妳，妳有MSN吗？以后CHE有问题就问你！ |
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发表于 24-5-2009 11:31 PM
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原帖由 meiling 于 20-5-2009 09:30 PM 发表 
我拿到41829哦？
还是请其他人来算算看。
我也不知道我的method对不对。
嗯。。是41829。。对了~~ |
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发表于 25-5-2009 05:02 PM
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原帖由 ★平常★ 于 24-5-2009 10:32 PM 发表 
If the ratio of Cl-35 to Cl-37 is 3:1,calculate the percentage abundance of the peaks.
想问妳，妳有MSN吗？以后CHE有问题就问你！
Cl2的可能性有
C3H635Cl35Cl =(3/4)(3/4)=9/16
C3H635Cl37Cl OR C3H637Cl35Cl =2(1/4)(3/4)=6/16
C3H637Cl37Cl =(1/4)(1/4)=1/16
然后就算PERCENTAGE，这个你应该会把？
你说怎样知道112的cl是35，116的cl是37。
你自己算MOLAR MASS。
就会知道了。
然后，你有什么问题就发在这里把。
这样大家就可以互相学习。
[ 本帖最后由 meiling 于 25-5-2009 05:03 PM 编辑 ] |
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发表于 25-5-2009 05:34 PM
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原帖由 ★平常★ 于 24-5-2009 10:21 PM 发表
有个问题，这样看112的cl是35，116的cl是37？
用trial and error的方法。
列出所有的可能性，然后一个一个算。 |
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楼主 |
发表于 25-5-2009 11:19 PM
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楼主 |
发表于 30-5-2009 08:49 AM
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大家！我又有问题了！
1)Why must the air be pumped out of a mass spectrometer,keeping it continuously under low pressure?
2)A sample of water weights 1.00g.
a)How many moles of water are there in 1.00g of water?
b)What volume(in cm³ of water vapour will be at r.t.p?
c)How many times larger is the volume of 1.00g of water vapour at r.t.p than 1.00gof the liquid?
d)Calculate the percentage of the volume of the vapour at r.t.p that the water molecules themselves occupy.(Assume that in liquid water the molecules are all in contact)
[ 本帖最后由 ★平常★ 于 30-5-2009 05:02 PM 编辑 ] |
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楼主 |
发表于 30-5-2009 05:03 PM
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帮忙解决下！ |
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发表于 30-5-2009 08:18 PM
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回复 16# meiling 的帖子
你的chemistry很好也~
很欣赏你这么厉害，我也要好好再温习一下我的化学了。
你是很好的学习对象。
看你们一来一往的讨论化学问题真的让我获益良多哦！谢谢。 |
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发表于 30-5-2009 11:44 PM
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回复 28# ★平常★ 的帖子
1. Vacuum ensures that ions that move along are not hindered by air particles.
2.a. use the formula mole=mass/R.A.M
b. use pV=nRT
c and d. water vapours are in the gaseous state, gases takes the sapce and shape of it's container, and most importantly it takes up the volume of the container too, without knowing the volume of the container, the questions could not be answered. |
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楼主 |
发表于 31-5-2009 08:14 AM
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回复 31# morphv02c01 的帖子
老师才教到第一课，这么酱快要用第二课了！
pV=nRT
原帖由 morphv02c01 于 30-5-2009 11:44 PM 发表 
c and d. water vapours are in the gaseous state, gases takes the sapce and shape of it's container, and most importantly it takes up the volume of the container too, without knowing the volume of the container, the questions could not be answered.
问题没给container的volume，要怎样算？
[ 本帖最后由 ★平常★ 于 31-5-2009 08:26 AM 编辑 ] |
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发表于 31-5-2009 09:28 PM
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ermm
你的问题全都是来自Longman书的吧~ |
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楼主 |
发表于 2-6-2009 09:44 AM
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原帖由 wahaha1 于 31-5-2009 09:28 PM 发表 
ermm
你的问题全都是来自Longman书的吧~
不知道咯！
老师给我纸我就做！ |
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楼主 |
发表于 7-6-2009 05:39 PM
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又要麻烦各位大大了！
1)The mass spectrum of neon ontains peaks at 20,21and 22
a) Assuming that only singly charged particles are produced,give the formula of the species responsible for the peaks at 20,21and 22!
b)The proton number of neon is 10.Calculate the number of neutrons present in each of the isotopes of neon .
2)Why is the relative atomic mass of chlorine 35.5 and not a whole number?
各位路过和帮忙解答的朋友，感恩你们肯花费时间！ |
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发表于 7-6-2009 06:38 PM
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原帖由 ★平常★ 于 31-5-2009 08:14 AM 发表
老师才教到第一课，这么酱快要用第二课了！
pV=nRT
问题没给container的volume，要怎样算？
from density of water tat is 1g/cm3
hence volume of water is 1cm3
继续汗，你们不要夸我了。
我这次中考chem才60分 |
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发表于 8-6-2009 06:29 PM
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原帖由 ★平常★ 于 7-6-2009 05:39 PM 发表
又要麻烦各位大大了！
1)The mass spectrum of neon ontains peaks at 20,21and 22
a) Assuming that only singly charged particles are produced,give the formula of the species responsible for the peaks at ...
1a)20: ^20ne^+, 21:^21ne^+,22:^22ne^+
b)^20ne^+ = 10
^21ne^+ = 11
^22ne^+ = 12
2) presence of isotope: 35^Cl and 37^Cl with different relative abundance |
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发表于 11-6-2009 11:50 PM
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原帖由 ★平常★ 于 20-5-2009 06:35 PM 发表
各位大大，可以叫我这题吗？
A molecule of a certain protein contains three nickel atoms.If 1g of the protein has 0.00421 g of nikel,what is the relative molecular mass of the protein?
1 mole of protein Ξ 3 moles of Nickle
3X{1/Mr(protein)} Ξ 0.00421/58.7
Mr(protein) = 41828.98
= 4.19 X 10^4 (3 s.f.)
希望我的答案能帮到你！！ |
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发表于 14-6-2009 06:51 PM
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这里果然很多强者，以后我会多来和大家一同讨论，学习的。 |
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发表于 14-6-2009 06:52 PM
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回复 38# 文锋 的帖子
我想问：
3X{1/Mr(protein)} Ξ 0.00421/58.7
为何protein那里要乘 3？ |
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