28.5 L of an unknown gas has a mass of 55.92 g at STP. What is the identity of the unknown gas? A. He B. O 2 C. N 2 D. CO 2
A gas mixture contains He, N2 , CO2 , and Ar. If a tiny hole is made in the container, which gas will effuse fastest? A. Ne B. Cl 2 C. SO 2 D. Ar
Solution
1)
at STP , 1 mol of gas occupies 22.4 L
now
amount of gas = 28.5 L x (1 mol / 22.4 L)
amount of gas = 1.27232 mol
now
molar mass of gas = mass / moles
molar mass of gas = 55.92 g / 1.27232 mol
molar mass of gas = 43.95 g
molar mass of gas = 44 g/mol
so
the gas is D) CO2
2)
molar mass of Ne ---> 20 g/mol
molar mass of Cl2 ---> 71 g/mol
molar mass of SO2 ---> 64 g/mol
molar mass of Ar ---> 40 g/mol
now
rate of effusion is inversely proportional to molar mass of the substance
so
lower the molar mass , higher the rate of effusion
so
A) Ne will effuse fastest
.
28-5 L of an unknown gas has a mass of 55-92 g at STP- What is the ide.docx
1. 28.5 L of an unknown gas has a mass of 55.92 g at STP. What is the identity of the unknown
gas? A. He B. O 2 C. N 2 D. CO 2
A gas mixture contains He, N2 , CO2 , and Ar. If a tiny hole is made in the container, which gas
will effuse fastest? A. Ne B. Cl 2 C. SO 2 D. Ar
Solution
1)
at STP , 1 mol of gas occupies 22.4 L
now
amount of gas = 28.5 L x (1 mol / 22.4 L)
amount of gas = 1.27232 mol
now
molar mass of gas = mass / moles
molar mass of gas = 55.92 g / 1.27232 mol
molar mass of gas = 43.95 g
molar mass of gas = 44 g/mol
so
the gas is D) CO2
2)
molar mass of Ne ---> 20 g/mol
2. molar mass of Cl2 ---> 71 g/mol
molar mass of SO2 ---> 64 g/mol
molar mass of Ar ---> 40 g/mol
now
rate of effusion is inversely proportional to molar mass of the substance
so
lower the molar mass , higher the rate of effusion
so
A) Ne will effuse fastest
