States of Matter

Long Answer Type

Advertisement
Zigya App

Explain the term surface tension.

To understand it, consider a molecule ‘M’ somewhere within the bulk of a liquid. It is attracted equally in all directions by the surrounding molecules. Hence, the net force of attraction acting on the molecule M is zero. However, a molecule ‘N’ on the surface of a liquid is attracted only by the molecules below and beside it and experiences a net downward attractive force. Thus, all molecules lying on the surface of liquid experience a net inward pull. This force which exerts an inward pull on the surface of a liquid and therefore, tends to keep the surface to a minimum is called surface tension. The liquid



thus behaves as if it were in a state of tension or strain. Thus, surface tension can be defined as the force acting at right angles to the surface along a unit length of the surface. As surface tension tends to keep the surface area of a liquid to the minimum due to inward pull, therefore, if the surface area of a liquid is to be increased, some work has to be done against this inward pull. Hence, surface tension may also be defined as a measure of work that must be done to expand the surface of a liquid by unit area. Surface tension is generally represented by γ and is expressed is Jm–2 (Joules/m2) or Nm–1 (Newton/m).
115 Views
  • Switch
    • Advertisement

    Short Answer Type

    Explain why alcohol produces a greater cooling effect on skin that water does.

    131 Views
    Answer

    Why is cooling caused in evaporation?

    119 Views
    Answer

    Will water boil at a higher temperature at sea level or on the top of a mountain ?

    140 Views
    Answer

    What do you understand by vapour pressure of solids?

    96 Views
    Answer
    Advertisement

    Long Answer Type

    Explain briefly the boiling point of a liquid. What is the effect of change in external pressure on the boiling point?

    138 Views
    Answer

    Short Answer Type

    Why does the temperature of the boiling liquid remain constant?

    114 Views
    Answer
    How will you differentiate between evaporation and boiling?
    124 Views
    Answer

    Separate portions of chloroform and water at the same temperature are poured on your hands. The chloroform feels colder. Account for this in terms of attractive forces.

    125 Views
    Answer
    Advertisement
    <

    What do you mean by state of dynamic equilibrium?

    110 Views
    Answer
    Advertisement