Triple point

(noun)

The unique temperature and pressure at which the solid, liquid and gas phases of a substance are all in equilibrium.

Related Terms

Examples of Triple point in the following topics:

  • Kelvin Scale

    • The kelvin is a unit of measurement for temperature; the null point of the Kelvin scale is absolute zero, the lowest possible temperature.
    • The Kelvin scale is an absolute, thermodynamic temperature scale using absolute zero as its null point.
    • The choice of absolute zero as null point for the Kelvin scale is logical.
    • The kelvin is defined as the fraction 1/273.16 of the thermodynamic temperature of the triple point of water (exactly 0.01°C, or 32.018°F).
    • Subtracting 273.16K from the temperature of the triple point of water, 0.01°C, makes absolute zero (0K) equivalent to -273.15°C and -460°F .

  • Absolute Temperature

    • Thermodynamic temperature is an "absolute" scale because it is the measure of the fundamental property underlying temperature: its null or zero point ("absolute zero") is the temperature at which the particle constituents of matter have minimal motion and cannot become any colder.
    • Therefore, it is reasonable to choose absolute zero, where all classical motion ceases, as the reference point (T=0) of our temperature system .
    • By international agreement, the unit kelvin and its scale are defined by two points: absolute zero and the triple point of Vienna Standard Mean Ocean Water (water with a specified blend of hydrogen and oxygen isotopes).
    • The triple point of water is defined precisely as 273.16 K and 0.01 °C.

  • Celsius Scale

    • From 1743 until 1954, 0°C was defined as the freezing point of water, and 100°C was defined as the boiling point of water, both at a pressure of one standard atmosphere, with mercury as the working material.
    • Although these defining correlations are commonly taught in schools today, by international agreement the unit "degree Celsius" and the Celsius scale are currently defined by two different temperatures: absolute zero and the triple point of Vienna Standard Mean Ocean Water (VSMOW; specially purified water).
    • The temperature of the triple point of water is defined as precisely 273.16K and 0.01°C.
    • In this typical phase diagram of water, the green lines mark the freezing point, and the blue line marks the boiling point, showing how they vary with pressure.

  • Unit Vectors and Multiplication by a Scalar

    • This results in a new vector arrow pointing in the same direction as the old one but with a longer or shorter length.
    • (ii) Multiplying the vector A by 3 triples its length.

  • World Energy Use

    • In the last 50 years, the global energy demand has tripled due to the number of developing countries and innovations in technology.
    • It is projected to triple again over the next 30 years.

  • Multiplying Vectors by a Scalar

    • (ii) Multiplying the vector $A$ by 3 triples its length.

  • Electric Field from a Point Charge

    • A point charge creates an electric field that can be calculated using Coulomb's law.
    • The electric field of a point charge is, like any electric field, a vector field that represents the effect that the point charge has on other charges around it.
    • If the charge is positive, field lines point radially away from it; if the charge is negative, field lines point radially towards it .
    • The electric field of a point charge is defined in radial coordinates.
    • The positive r direction points away from the origin, and the negative r direction points toward the origin.

  • Stress and Strain

    • A point charge creates an electric field that can be calculated using Coulomb's Law.
    • The electric field of a point charge is, like any electric field, a vector field that represents the effect that the point charge has on other charges around it.
    • If the charge is positive, field lines point radially away from it; if the charge is negative, field lines point radially towards it.
    • The electric field of a point charge is defined in radial coordinates.
    • The positive r direction points away from the origin, and the negative r direction points toward the origin.

  • Electric Potential Due to a Point Charge

    • The electric potential of a point charge Q is given by $V=\frac{kQ}{r}$.
    • Point charges, such as electrons, are among the fundamental building blocks of matter.
    • The electric potential due to a point charge is, thus, a case we need to consider.
    • Thus V for a point charge decreases with distance, whereas E for a point charge decreases with distance squared:
    • Express the electric potential generated by a single point charge in a form of equation

  • Farenheit Scale

    • On this scale, water's freezing point is defined to be 32 degrees, while water's boiling point is defined to be 212 degrees.
    • The second determining point, 32 degrees, was a mixture of just ice and water at a 1:1 ratio.
    • The Fahrenheit system puts the boiling and freezing points of water exactly 180 degrees apart.
    • Therefore, a degree on the Fahrenheit scale is 1/180 of the interval between the freezing point and the boiling point.
    • On the Celsius scale, the freezing and boiling points of water are 100 degrees apart.