Revision Questions: The Particle Model, Pressure

Wherever you see an input box in the following text, please fill in the correct words or numbers (to 2 d.p. where appropriate). You might well need a calculator to do this, so here are some links to a few online calculators. They all open up in new tabs, and at least one of them should work!

https://www.calculator.net/scientific-calculator.html
https://www.geogebra.org/scientific
https://web2.0calc.com/

  1. The figure on the right shows a balloon filled with helium gas.

    1. Describe the movement of the particles of helium gas inside the balloon. [2 marks]


    2. What name is given to the total kinetic energy and potential energy of all the particles of helium gas in the balloon? Type one of the following words: External, Internal, Movement
      Answer: [1 mark]

    3. Write down the equation which links density, mass and volume. [1 mark]
      Answer:

    4. The helium in the balloon has a mass of 0.00254kg. The balloon has a volume of 0.0141m3. Calculate the density of helium. Choose the correct unit from the box by typing its letter. [3 marks]
      A. m3/kg B. kg/m3 C. kg m3
      Density = Unit =

  2. In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.

    The information in the box is about the properties of solids and gases.
    Solids:
    • have a fixed shape
    • are difficult to compress (squash)
    Gases:
    • will spread and fill the entire container
    • are easy to compress
    Use your knowledge of kinetic theory to explain the information given in the box. You should consider: [6 marks]

  3. Use your knowledge of the particle model to explain the following observations:

    1. If you press your thumb tightly over the end of a bicycle pump and then thrust the piston of the pump in slowly, you will feel a great deal of pressure from the gas in the pump against the end of your thumb. [2 marks]


    2. When someone is cooking bacon and eggs in a kitchen, the smell of the cooking spreads slowly throughout the house, reaching the furthest rooms last of all, after several minutes. [2 marks]

  4. The apparatus shown on the right shows two sealed glass flasks, A and B, connected by a valve V. A small amount of liquid bromine is placed in A before V is closed and B is connected. The other connection on B is to a vacuum pump that can be used to remove all the air from B.

    Bromine is volatile, bright orange liquid that readily forms an orange vapour above the surface of the liquid, and the gas in A soon turns orange.

    1. What is the meaning of the word volatile in this context? [1 mark]


    2. The vacuum pump is turned off and air is allowed into B. When V is opened, what is observed, and why? [3 marks]


    3. What is the name of the effect that caused the observation you have described? [1 mark]

    4. The equipment is reset and this time the vacuum pump is used to remove all the air from B. What happens when V is opened this time, and why is it different from the previous case? [3 marks]