Equal moles of hydrogen and oxygen gases are placed in container with a pin-hole through which both can escape. What fraction of the oxygen escapes in the time required for one-half of the hydrogen to escape?
(a) 1/4 (b) 3/8 (c) 1/2 (d) 1/8
(d) Given, number of moles of hydrogen () and that of oxygen () are equal.
... We have, the relation between ratio of number of moles escaped and ratio of molecular mass.
where, M = Molecular mass of the molecule
= 0.5/4 =1/8
A gas such as carbon monoxide would be most likely to obey the ideal gas law at
(a) high temperatures and low pressures
(b) low temperatures and high pressures
(c) high temperatures and high pressures
(d) low temperatures and low pressures
Real gases show ideal gas behaviour at high temperature and low pressures.
Equal masses of H2, O2 and methane have been taken in a container of volume V at temperature 27°C in identical conditions. The ratio of the volumes of gases H2: O2 : CH4 would be
(c) According to Avogadro's hypothesis, Volume of a gas (V) number of moles (n)
Therefore, the ratio of the volumes of gases can be determined in terms of their moles. The ratio of volumes of H2: O2:methane (CH4)
is given by
When 22.4 L of H2 (g) is mixed with 11.2 L of Cl2 (g), each at STP, the moles of HCl(g) formed is equal to
(a) 1 mole of HCl (g)
(b) 2 moles of HCl (g)
(c) 0.5 mole of HCl (g)
(d) 1.5 mole of HCl (g)
The given problem is related to the concept of stiochiometry of chemical equations. Thus, we have to convert the given volumes into their moles and then, identify the limiting reagent [possessing minimum number of moles and gets completely used up in the reaction].
The limiting reagent gives the moles of product formed in the reaction.
H2(g) + Cl2(g) 2HCl (g)
Initial vol 22.4 L 11.2 L 2 mol
... 22.4 L volume at STP is occupied by,
Cl2 = 1 mole,
... 11.2 L volume will be occupied by,
Cl2 = 1x 11.2/22.4 mole = 0.5 mol
Thus, H2(g) + Cl2(g) 2HCl (g)
Maximum derivation from ideal gas is expected from:
(d) Easily liquefiable gases like NH3, SO2 etc. exhibit maximum deviation from ideal gas as for them Z<<< 1 .
also exhibits deviation but it is less as compared to NH3.
A gaseous mixture was prepared by taking equal moles of CO and N2. If the total pressure of the mixture was found 1 atmosphere, the partial pressure of the nitrogen (N2) in the mixture is
(a) 0.8 atm
(b) 0.9 aim
(c) 1 atm
(d) 0.5 atm
Pco = PN2
Given, Pco + PN2 = 1atm
or 2PN2 = 1 atm
or PN2 = 0.5atm
Two gases A and B having the same volume diffuse through a porous partition in 20 and 10 seconds respectively. The molecular mass of A is 49 u. Molecular mass of B will be
(a) 12.25 u
(b) 6.50 u
(c) 25.00 u
(d) 50.00 u
By what factor does the average velocity of a gaseous molecule increase when the temperature (in Kelvin) is doubled?
Average velocity =
or (Vav)2 / (Vav )1 = = 1.4
If a gas expands at constant temperature, it indicates that
(a) kinetic energy of molecules decreases
(b) pressure of the gas increases
(c) kinetic energy of molecules remains the same
(d) number of the molecules of gas increases
Key Idea: KE = 3/2RT
KE ∝ T
Here, the temperature of gas remains constant, hence kinetic energy of molecules remains the same.
What volume of oxygen gas (O2) measured at 0°C and 1 atm, is needed to burn completely 1 L of propane gas (C3H8) measured under the same conditions?
Key Idea: Volume of a gas STP = 22.4L
To burn 22.4 L C3H8 the oxygen required is = 5 x 22.4 L
To burn 1 LC3H8 the oxygen required will be = 5 x 22.4 / 22.4 = 5L