Chemical Engineering

Analyses of Multicomponent Solutions and Mixtures

Question 1
Marks : +2 | -2
Pass Ratio : 50%
A compound contain 12% of carbon, 16% of oxygen, 28% of nitrogen, 4% of hydrogen and 40% calcium by weight, then what can be the possible formula of the compound?
C2H3N2Ca(OH)
CH4N4Ca2(OH)
CH3N2Ca2(OH)
None of the mentioned
Explanation:
Ration of number of atoms, carbon: hydrogen: oxygen: nitrogen: calcium = 12/12: 4/1: 16/16: 28/14: 40/20 = 1:4:1:2:2.
Question 2
Marks : +2 | -2
Pass Ratio : 50%
A liquid mixture of O2, CH4 and CO has the composition 32% O2, 16% CH4 and 52% CO, then what is the mole fraction of CH4?
0.1
0.2
0.25
0.5
Explanation:
Let the total weight of the mixture be 100 g, => weight of each component are 32 g, 16 g and 52 g respectively, => moles of O2 = 32/16 = 2, moles of CH4 = 16/16 = 1, moles of CO = 52/26 = 2 g, => mole fraction of CH4 = 1/5 = 0.2.
Question 3
Marks : +2 | -2
Pass Ratio : 50%
What is the molecular weight of a mixture that contains 25% CO2, 40% O2 and 35% N2?
11.2 g
22.4 g
33.6 g
44.8 g
Explanation:
Molecular weight = (25*44 + 40*32 + 35*28)/100 = 33.6 g.
Question 4
Marks : +2 | -2
Pass Ratio : 50%
A gaseous mixture composed of 20% CH4, 30% C2H4, 35% C2H2, and 15% C2H2O. What is the average molecular weight of the mixture?
20
25
6.75
9.25
Explanation:
Since it is a gaseous mixture so the percentages are by mole, => average molecular weight of mixture = {(20/100)*16 + (30/100)*28 + (35/100)*26 + (15/100)*42}/4 = 6.75.
Question 5
Marks : +2 | -2
Pass Ratio : 50%
What is the weight of 10 moles of a mixture with composition 15% O2, 25% SO2, 30% COCl2, 25% SO3 and 5% N2?
124
345
507
719
Explanation:
Molecular weight of mixture = (15*32 + 25*64 + 30*99 + 25*80 + 5*28)/100 = 71.9, => Weight of mixture = 71.9*10 = 719.
Question 6
Marks : +2 | -2
Pass Ratio : 50%
If a compound contains 48% of Carbon, 48% of oxygen and 8% of hydrogen by weight, then what is the possible molecular formula of the compound?
C2H4O
CH4O3
C4H4O3
C4H8O3
Explanation:
Ratio of number of atoms, Carbon: Hydrogen: Oxygen = 48/12: 8/1: 48/16 = 4:8:3.
Question 7
Marks : +2 | -2
Pass Ratio : 50%
A liquid mixture composed of 20% CH4, 30% C2H4, 35% C2H2, and 15% C2H2O. What is the average molecular weight of the mixture?
20
25
6.75
9.25
Explanation:
Since it is a liquid mixture so the percentages are by weight, => average molecular weight of mixture = (20 + 30 + 35 + 15)/4 =25.
Question 8
Marks : +2 | -2
Pass Ratio : 50%
A gaseous mixture is composed of 20% CO2, 40% O2 and 40% N2. What is the mass fraction of N2?
0.307
0.416
0.529
0.784
Explanation:
Let the total moles of the mixture be 100, => mass of CO2 = 20*44 = 880 g, mass of ¬O2 = 40*16 = 640 g, mass of N2 = 40*14 = 560 g, => mass fraction of N2 = 560/(880 + 640 + 560) = 0.307.
Question 9
Marks : +2 | -2
Pass Ratio : 50%
If hydrogen is 14% by weight in CH3(OH)x(NH3)y, then what is the possible value of x*y?
6
12
18
24
Explanation:
Let the weight of compound be 100 g, => weight of hydrogen = 14 g, => 3y + x + 3 = 14 => 3y + x = 11, => and 12 + 14 + 16x + 14y = 100, => 8x + 7y = 37, solving both equations we get x = 2 and y = 3, => x*y = 6.
Question 10
Marks : +2 | -2
Pass Ratio : 50%
What is the value of x in C2H8(OH)x if the percentage by weight of hydrogen is 12%?
1
2
3
4
Explanation:
Let the total weight of the compound be 100 g, => weight of hydrogen in the compound is 12 g, => x = 12 – 8 = 4.