(Chem) 關於mole的問題

2008-05-17 9:49 pm

1. Element X forms two oxides, XO2 and XO3. If one mole of XO2 contain n atom, 3 mole of XO3 would contain ?n

2. A solid mixture of iron(II) nitrate and iron(II) carbonate contains 1.0 mole of nitrate ions and 1.2 moles of iron(II) ions. What is the number of moles of carbonate ions in the mixture ?

3. Consider the following equation:
X2 (g) + 3Y2(g) ---------------> 2XY2 (g)
If 4 moles of X2 (g) react with 6 moles of Y2 (g), What is the number of
moles of XY2(g) formed ?

更新1:

Uncle Michael ( 博士級 1 級 ) : 頭二絛我都明呀, thx =) 但第三條打錯了, can you explain to me ? 3. Consider the following equation: X2 (g) + 3Y2(g) ---------------> 2XY3 (g) If 4 moles of X2 (g) react with 6 moles of Y2 (g), What is the number of moles of XY3(g) formed ?

回答 (2)

Uncle Michael

2008-05-18 9:47 am

✔ 最佳答案

1.
Denote the Avogadro number as L.
No. of moles of atoms in 1 mol of XO2 = 1 x 3 = 3 mol
No. of atoms in 1 mol of XO2 = 3L atoms
Hence, n = 3L

No. of moles of atoms in 3 mol of XO3 = 3 x 4 = 12 mol
No. of atoms in 3 mol of XO3 = 12L = 4(3L) = 4n

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2.
Assume the mixture contains x mol of Fe(NO3)2 and y mol of FeCO3.

x mol of Fe(NO3)2 contains x mol of Fe2+ ions and 2x mol of NO3- ions.
y mol of FeCO3 contains y mol of Fe2+ ions and y mol of CO32- ions.

No. of moles of NO3- ions = 2x = 1
Hence, x = 0.5

No. of moles of Fe2+ ions = x + y = 1.2
0.5 + y = 1.2
Hence, y = 0.7

No. of moles of CO32- = y = 0.7 (mol)

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3.
If they are X2, Y2 and XY2 respectively, the equation should be
X2(g) + 2Y2(g) → 2XY2
Mole ratio required X2 : Y2 = 1 : 2
Mole ratio added X2 : Y2 = 4 : 6 = 1.33 : 2
Obviously, X2 is in excess and Y2 is the limiting reactant.

Mole ratio Y2 : XY2 = 2 : 2 = 1 : 1
No. of moles of Y2 used = 6 mol (limiting reactant)
No. of moles of XY2 formed = 6 mol

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自由人

2008-05-17 10:16 pm

(1)n atoms
1 mole of the substance always contains 6.02 x 10^23 atoms.
(2)1.0 mole
The mole rate of nitrate ions and carbonate ions are same.
(3)8 moles
mole rate of X2:XY2=1:2
number of mole of XY2=4 x 2=8

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