1. The mole fraction of carbon dioxide in a gas mixture is 0.150. There are 0.25
ID: 857244 • Letter: 1
Question
1. The mole fraction of carbon dioxide in a gas mixture is 0.150. There are 0.251 g of nitrogen and 0.322 g of oxygen in this gas mixture. What is the mass of carbon dioxide in this mixture?
2. 2.13 g of CCH4(g) is mixed with 15.0 of Br2(g) in a 2.35 L container. What is the mole fraction of Br2(g) present in the mixture?
3. An unknown gas is placed in a 1.500 L bulb at a pressure of 356 mm Hg and a temperature of 22.5 ?C, and is found to weigh 0.9266g .
(( on this question i keep getting 4 different answers. )))
4. What is the total pressure in a 8.00-L flask which contains 0.127 mol of H2(g) and 0.288 mol of N2(g) at 20.0?C?
Can someone help me in these for question, Show me step by step on how to solve them. I've been stuck on these questions for 2 days!!! thank you!!!!
Explanation / Answer
1. The mole fraction of carbon dioxide in a gas mixture is 0.150. There are 0.251 g of nitrogen and 0.322 g of oxygen in this gas mixture. What is the mass of carbon dioxide in this mixture?
Ans:
Mole fraction = moles of compound / total moles
Mass of nitrogen = 0.251 g , atomic wt of nitrogen = 28 so moles = 0.251 /28 = 0.0089
Mass of oxygen = 0.322 g. At wt of oxygen = 32 so moles = 0.010
Mole fraction of carbon dioxide =
moles of CO2 / moles of O2 + N2 + CO2
0.15 = moles of CO2 / 0.010 + 0.0089 + moles of CO2
0.15( 0.010 + 0.0089 +x) = x = 0.0015 + 0.00135 + 0.15 x
0.85x = 0.00285
X=0.0033 moles of CO2
So mass = moles X mol wt of CO2 = 0.1452g
2. 2.13 g of CCH4(g) is mixed with 15.0 of Br2(g) in a 2.35 L container. What is the mole fraction of Br2(g) present in the mixture?
Ans: moles of CH4 = 2.13 / 16 = 0.133 moles
Moles of Br2 = 15 / 80 = 0.1875
Mole fraction of Br2 = 0.1875 / 0.1875 + 0.133 = 0.5850
3. An unknown gas is placed in a 1.500 L bulb at a pressure of 356 mm Hg and a temperature of 22.5 ?C, and is found to weigh 0.9266g .
PV=nRT
1mm Hg = 0.0013 atm
P = 0.4628 atm
R= gas constant = 0.0821 L atm K-1 mol-1
Temp = 273 + 22.5 = 295.5 K
Volume = 1.5L
n = 0.4628 X 1.5 / 0.0821 X 295.5 = 0.028 moles
so mol wt = mass / moles = 33.09
(( on this question i keep getting 4 different answers. )))
4. What is the total pressure in a 8.00-L flask which contains 0.127 mol of H2(g) and 0.288 mol of N2(g) at 20.0?C?
Can someone help me in these for question, Show me step by step on how to solve them. I've been stuck on these questions for 2 days!!! thank you!!!!
Ans
Pressure of Hydrogen = nRT / V = 0.127 X 0.0821 X 293 / 8 =0.3818 atm
Pressure of Nitrogen = nRT / V = 0.0.288 X 0.0821 X 293 / 8 = 0.8659 atm
Total pressure = 1.247 atm
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