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Chapter: 11th Chemistry : Gaseous State

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Brief Questions and Answers: Gaseous State (Chemistry)

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 (H2) 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 F2, Cl2, or Br2? 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, NH4Cl 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.



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?



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.



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



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.



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.



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?



53. It takes 192 sec for an unknown gas to diffuse through a porous wall and 84 sec for N2 gas to effuse at the same temperature and pressure. What is the molar mass of the unknown gas?



54. A tank contains a mixture of 52.5 g of oxygen and 65.1 g of CO2 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.



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).


Pressure of the gas in the tank at its melting point

T1 = 298 K ; P1 = 2 .98 atom; T2 = 1100 K; P2 = ?

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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