A) The stages involved in the Contact Process can be represented by the following equations:
S(s) +O₂ (g)-->SO₂ (g)
2SO₂ (g) +O₂-->2SO₃ (g)
SO₃ (g) +H₂SO₄ (l)-->H₂S₂O7(l)
H₂S₂O7(l) +H₂O(l)-->2H₂SO₄
Suppose that the conversion of sulphur to sulphuric acid is 100%.
1) How many moles of sulphur are required to produce one mole of sulphuric acid?
2)If the annual production of sulphuric acid in this country is 2.6x10^9kg, calculate the annual consumption of sulphur, in kg, in the Contact Process.
B) The relative molecular mass of an alkanol X (CnH₂n+₁OH) is 60.0. X contains 60% of carbon by mass. Calculate the number of moles of carbon in one mole of X and hence deduce the molecular formula of X.
mole 問題
2008-03-09 5:17 pm
回答 (2)
2008-03-10 10:45 pm
✔ 最佳答案
(A)(1)1 mol of S is needed to produce 1 mol of H2SO4.
Reason :
Step 1 : 1 mol S → 1 mol SO2
Step 2 : 1 mol SO2 → 1 mol SO3
Step 3 : 1 mol SO3 + 1 mol H2SO4 → 1 mol H2S2O7
Step 4 : 1 mol H2S2O7 → 2 mol H2SO4
Although there are 2 mol of H2SO4 produced in step 4, only 1 mol of H2SO4 is produced from S. This is because 1 mol of H2SO4 is added in Step 3.
(Both (A)(1) and (A)(2) are past HKCE questions.)
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(A)(2)
Molar mass of S = 32.1 g mol-1
Molar mass of H2SO4 = 2x1 + 32.1 + 16x4 = 98.1 g mol-1
Mole ratio of S : H2SO4 = 1 : 1
Mass of H2SO4 produced = 2.6 x 109 kg = 2.6 x 1012 mol
No. of mol of H2SO4 produced = (2.6 x 1012) / 98.1 = 2.65 x 1010 mol
Mass of S needed = (2.65 x 1010) x 32.1 = 8.51 x 1011 g = 8.51 x 108 kg
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(B)
In 1 mol of X (CnH2n+1OH) :
Mass of X = Molar mass of X = 60 g
Mass of C in X = Mass of n mol of C = 12n g
(12n/60) x 100% = 60%
Hence, n = 3
Molecular formula of X = CnH2n+1OH = C3H7OH
2008-03-09 5:38 pm
A 1. 0.5 mole of sulphur is needed.
2. the number of mole of sulphuric acid =2.6x10^9 /98=2.65x10^7mole
since the number of mole of sulphur is half of sulphuric acid,
the no. of mole of sulphur is 2.65x10^7 x0.5
= 1.3x10^7 mole
the mass of sulphur =1.3x10^7 x 32= 4.16x10^8 kg
B the mass of carbon =60x 60% =36
the no of mole of carbon=36/12=3
the molecular formula is C3H7OH
2. the number of mole of sulphuric acid =2.6x10^9 /98=2.65x10^7mole
since the number of mole of sulphur is half of sulphuric acid,
the no. of mole of sulphur is 2.65x10^7 x0.5
= 1.3x10^7 mole
the mass of sulphur =1.3x10^7 x 32= 4.16x10^8 kg
B the mass of carbon =60x 60% =36
the no of mole of carbon=36/12=3
the molecular formula is C3H7OH
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