Week Seven

"Alkali Earth Metal of the week"

"Ba" 56

Barium;
the chemical element of atomic number 56, a soft white reactive metal of the alkaline earth group.
Medicine a mixture of barium sulphate and water ,opaque to X-rays, which is swallowed
to parmit radiological examination of the stomach or intestines.
by Concice Oxford Dictionary.

My mother said that was hard to drink(swallow) it. I have not been yet.


Avogadro's Hypothesis
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What exactly is a mole?

I am using in japanese for my understanding.


Atomic weight 　　　Ｏ＝１６．０ Ｎａ＝２３．０ Ｓ＝３２．０ Ｃｌ＝３５．５ Ｃa=40.0
Avogadro's Number 　6.022×１０^23

Q1 Na2SO4 14.2ｇが水に溶け、完全に電離したとすると、存在する総イオン数はどれだけか。

Q2 水にＣａＣｌ2を溶かして、Ｃｌ－を0.10molつくりたい。ＣａＣｌ2を何ｇ溶かせば良いか。
ただしＣａＣｌ2は完全に電離するものとする。




Na2SO4 molecular weight＝（23.0×2）　+　（32.0×1）+　（16.0×4）　=142

therefore Na2SO4→ 1 mole　＝１４２ｇ

1mole Na2SO4 → Na2SO4が 6.022×10^23個

Na2SO4が14.2ｇ → 0.1 mole

さて、Na2SO4が電離すると → ２Na+ SO4(2-)
total ion = 0.1mole × 6.022×10^23×(2+1)= 1.8×10^23個

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Q2
Cl-が0.1mol→CaCl2を0.05mol溶かせばいいわけですから
(40+35.5×２)×0.05=5.55ｇ

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About "Chikyu"

I checked web-site below about "Chikyu" .

http://www.jamstec.go.jp/chikyu/eng/index.html

If you have interest in it please check these web-site .



If Chikyu could reach "Earthquake nest" it will be really help us because earthquake is very serious problem and often happen in Japan.Untill now many people died by earthquake . I remenber there was an earthquake of magnitude 7.3 early morning around 5am in Kobe (west of Japan) . In January 1995 , 6,500 people died by the Great Hanshin-Awaji Earthquake . It was very daring news.