Chemistry : Gaseous State : Brief Questions and Answers

**26. State Boyle's law.**

**27. A balloon filled with air at
room temperature and cooled to a much lower temperature can be used as a model
for Charle’s law**

**28. Name two items that can serve as
a model for Gay Lusaac’ law and explain.**

**29. Give the mathematical expression
that relates gas volume and moles. Describe in words what the mathematical
expression means.**

**30. What are ideal gases? In what
way real gases differ from ideal gases.**

**31. Can a Van der Waals gas with a=0
be liquefied? explain.**

**32. Suppose there is a tiny sticky
area on the wall of a container of gas. Molecules hitting this area stick there
permanently. Is the pressure greater or less than on the ordinary area of walls?**

**33. Explain the following
observations**

**a) Aerated water bottles are kept
under water during summer**

**b) Liquid ammonia bottle is cooled
before opening the seal**

**c) The tyre of an automobile is
inflated to slightly lesser pressure in summer than in winter**

**d) The size of a weather balloon
becomes larger and larger as it ascends up into larger altitude**

**34. Give suitable explanation for
the following facts about gases.**

**a) Gases don’t settle at the bottom
of a container**

**b) Gases diffuse through all the
space available to them and**

**35. Suggest why there is no hydrogen
(H _{2}) in our atmosphere. Why does the moon have no atmosphere?**

**36. Explain whether a gas approaches
ideal behavior or deviates from ideal behaviour if**

**a) it is compressed to a smaller
volume at constant temperature.**

**b) the temperature is raised at
while keeping the volume constant**

**c) more gas is introduced into the
same volume and at the same temperature**

**37. Which of the following gases
would you expect to deviate from ideal behaviour under conditions of low
temperature F _{2}, Cl_{2}, or Br_{2}? Explain.**

**38. Distinguish between diffusion
and effusion.**

**39. Aerosol cans carry clear warning
of heating of the can. Why?**

**40. When the driver of an automobile
applies brake, the passengers are pushed toward the front of the car but a
helium balloon is pushed toward back of the car. Upon forward acceleration the
passengers are pushed toward the front of the car. Why?**

**41. Would it be easier to drink
water with a straw on the top of Mount Everest?**

**42. Write the Van der Waals equation
for a real gas. Explain the correction term for pressure and volume**

**43. Derive the values of van der
Waals equation constants in terms of critical constants.**

**44. Why do astronauts have to wear
protective suits when they are on the surface of moon?**

**45. When ammonia combines with HCl,
NH _{4}Cl is formed as white dense fumes. Why do more fumes appear near
HCl?**

**46. A sample of gas at 15 °C at 1
atm. has a volume of 2.58 dm3. When the temperature is raised to 38 °C at 1 atm
does the volume of the gas increase? If so, calculate the final volume.**

**Answer:**

**47. A sample of gas has a volume of
8.5 dm3 at an unknown temperature. When the sample is submerged in ice water at
0 °C, its volume gets reduced to 6.37 dm3. What is its initial temperature?**

**Answer:**

**48. Of two samples of nitrogen gas,
sample A contains 1.5 moles of nitrogen in a vessel of volume of 37.6 dm3 at
298K, and the sample B is in a vessel of volume 16.5 dm3 at 298K. Calculate the
number of moles in sample B.**

**Answer:**

**49. Sulphur hexafluoride is a
colourless, odourless gas; calculate the pressure exerted by 1.82 moles of the
gas in a steel vessel of volume 5.43 dm3 at 69.5 °C, assuming ideal gas
behaviour**

**Answer:**

**50. Argon is an inert gas used in
light bulbs to retard the vaporization of the tungsten filament. A certain
light bulb containing argon at 1.2 atm and 18°C is heated to 85°C at constant
volume. Calculate its final pressure in atm.**

**Answer:**

**51. A small bubble rises from the
bottom of a lake where the temperature and pressure are 6°C and 4 atm. to the
water surface, where the temperature is 25°C and pressure is 1 atm. Calculate
the final volume in (mL) of the bubble, if its initial volume is 1.5 mL.**

**Answer:**

**52. Hydrochloric acid is treated
with a metal to produce hydrogen gas. Suppose a student carries out this
reaction and collects a volume of 154.4 × 10-3 dm3 of a gas at a pressure of
742 mm of Hg at a temperature of 298 K. What mass of hydrogen gas (in mg) did
the student collect?**

**Answer:**

**53. It takes 192 sec for an unknown
gas to diffuse through a porous wall and 84 sec for N _{2} gas to effuse
at the same temperature and pressure. What is the molar mass of the unknown
gas?**

**Answer:**

**54. A tank contains a mixture of
52.5 g of oxygen and 65.1 g of CO _{2} at 300 K the total pressure in
the tanks is 9.21 atm. Calculate the partial pressure (in atm.) of each gas in
the mixture.**

**Answer:**

**55. A combustible gas is stored in a
metal tank at a pressure of 2.98 atm at 25 °C. The tank can withstand a maximum
pressure of 12 atm after which it will explode. The building in which the tank
has been stored catches fire. Now predict whether the tank will blow up first
or start melting? (Melting point of the metal = 1100 K).**

**Answer:**

Pressure of the gas in the tank
at its melting point

T_{1} = 298 K ; P_{1} = 2 .98 atom; T_{2} = 1100 K; P_{2} = ?

At 1100 K the pressure of the gas
inside the tank will become 11 atm. Given that tank can withstand a maximum
pressure of 12 atm, the tank will start melting first.

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