關於dilution一問…

Question

點解用water dilute 左既solute，solute 既no. of moles 會同dilute 前一樣既？ie no. of moles before dilution=no. of moles after dilution.
最好詳盡d，因為本人問完老師+同學都唔明
thx~

Answer 1

no. of moles of solute 其實是指溶液內 solute 分子的數目﹐ 1 mole = 6.02 x 1023(Avogadro's number) 粒分子。
用加水的方法把溶液 dilute﹐其實只是增加它的體積而已。雖然濃度是減少了﹐但是 solute 分子的數目並沒有改變﹐所以並不影響 number of moles of solute。
舉一個簡單的例子﹕
一個 100 平方米的房間裡面有 10 個人﹐現在把這 10 個人搬到一個 1000 平方米的房間裡面﹐雖然房間裡面人的密度是減少了 (變得沒那麼擠逼)﹐但是人的數目並沒有改變。

Answer 2

因為Solution 裏面有 溶質 + 溶劑.

假設
溶質係 糖
溶劑係 水

咁不停加水~~d糖唔會少嫁嘛...
no of mole就指 糖既數目
所以dilute左~~即係唔會影響佢既糖既數目la

因為假設物質不滅
所以concentration有變~但no of mole 不變．．

Answer 3

A solution is made by dissolving a solute into a solvent (usually water). In a solution, there are a solute and a solvent.

When a solution is dilute, solvent is added to the solution. Therefore,
(1) the amount of solvent is increased.
(2) the amount of solute is unchanged, since no solute is added nor removed in dilution.
Hence, number of moles of solute dilution = number of moles of solute after dilution

For example, there are 0.01 mol of NaCl dissolved in 10 mol of water. The solution is then diluted by adding 90 mol of water.
No. of moles of water after dilution = 10 + 90 = 100 mol (increased)
No. of moles of NaCl = 0.01 mol (unchanged)

2007-04-20 23:55:37 補充：
The last line of the green words should be :Hence, number of moles of solute before dilution = number of moles of solute after dilution