chem mole helpp!!again

159.
The answer is : C. 44.5 g

Mole ratio H2SO4 : FeSO4•7H2O = 1 :1
No. of moles of H2SO4 = 1.6 x (100/1000) = 0.16 mol
No. of moles of FeSO4•7H2O = 0.16 mol
Molar mass of FeSO4•7H2O = 56 + 32 + 16x4 + 7x(1x2 + 16)= 278 g/mol
Mass of FeSO4•7H2O obtained = 0.16 x 278 = 44.5 g


160.
答案是： A. 30.0 cm³

X(OH)2 + 2HNO3 → 2XNO3 + 2H2O
No. of moles of X(OH)2 used in titration = (5.13/171) x (25/250) =0.003 mol
No. of moles of HNO3 used in titration = 0.003 x 2 = 0.006 mol
Volume of nitric acid = 0.006/0.2 = 0.03 dm³ = 30.0 cm³


162.
The answer is : A. (1) and (2) only

(1) is true.

(2) is true.
This is to avoid the dilution of the solution to be filled by the distilledwater left in the pipette.

(3) is false.
Left the last drop of the solution in the pipette.


165.
The answer is : A

Both statements are true and the 2nd statement is a correct explanation of the1st statement.


166.
The answer is : D

H⁺(aq) + OH⁻(aq) → H­2O(l)
No. of moles of H2SO4 = 1 x (100/1000) = 0.1 mol
No. of moles of H⁺ ions = 0.1 x 2 = 0.2 mol
No. of moles of NaOH = 1 x (100/1000) = 0.1 mol
No. of moles of OH⁻ ions = 0.1 mol

The 1st statement is false. As the number of moles of H⁺ ions is NOT equal to thatof OH⁻ ions, the neutralizationis NOT complete.

The 1st statement is false. The number of moles of H⁺ ions is NOT equal to thatof OH⁻ ions.

2012-11-20 01:44:33 補充：
在題2中，2XNO3 應為 X(NO3)2 之誤。
但此對計算並無影響。

謝謝魔龍帝齊格益力多的提醒。

160:
X(OH)2+2HNO3-------->X(NO3)2+2H2O
mole of X(OH)2 in 25 cm^3=(5.13/171)(25/250)=3(10^-3)mol
Volume of HNO3=(3(10^-3)*2)/0.2=0.03dm^3=30cm^3
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To賣女孩的火柴:Your equation has some mistakes.