Q:

How does a thermos flask keep warm?

A:

Thermos flasks are designed to hinder heat transfer between the liquid placed within them and the surrounding environment. The insides and outsides of flasks are often silvered to impede heat transfer through radiation. The interior of the flask is also made of a thermal insulator to impede heat conduction.

Know More

Full Answer

A thermos flask prevents heat transfer through conduction and convection using a partial vacuum between two containers, one placed within the other. This partial vacuum impedes the transfer of thermal kinetic energy between the molecules within the flask and those outside it, making it suitable for keeping chilled drinks cold and hot drinks warm. The inner flask is often made from borosilicate glass of low thermal conductivity to further aid in preventing conduction. Flasks may also feature a silver coating that prevents heat transfer through infrared radiation.

The original vacuum flask was invented by Sir James Dewar in 1892. The Dewar flask was similar to the modern design, consisting of two flasks placed one within the other, with contact only at the neck. Dewar’s original design was made to keep palladium samples at a constant temperature to facilitate calorimetry measurements. In 1904, Dewar’s design was commercialized by German glassblowers, who renamed the flask Thermos.

Learn more in Thermodynamics

Related Questions

  • Q:

    What is the difference between conduction and convection?

    A:

    Conduction is heat transfer through solid objects, while convection is heat transfer through liquid or gasses. Conduction and convection are both forms of radiation, which is heat transfer.

    Full Answer >
    Filed Under:
  • Q:

    Why is boiling a cooling process?

    A:

    Boiling can be considered as a cooling process because as a liquid reaches its critical temperature, heat escapes through rapid evaporation. Essentially, boiling happens when liquids turn into gases, forcing excess heat out of the liquid.

    Full Answer >
    Filed Under:
  • Q:

    How does the liquid in a glass thermometer work?

    A:

    The liquid in a glass thermometer, either colored alcohol or mercury, expands as it heats and condenses as it cools. In a thermometer, the liquid cannot expand outward and the only place it can go is up or down. Temperature on a glass thermometer can be measured in Fahrenheit, Celsius or Kelvin.

    Full Answer >
    Filed Under:
  • Q:

    What temperature is lukewarm?

    A:

    If the term lukewarm is in reference to a liquid like milk or water for a recipe, then this temperature is anywhere between 98 to 105 degrees Fahrenheit. This temperature also is comparable to combining one part of water that is at room temperature with two parts of boiling water. When preparing milk formula, lukewarm is usually the ideal temperature range.

    Full Answer >
    Filed Under:

Explore