Answer
Verified
393.6k+ views
Hint: The third law of thermodynamics relates the entropy of the crystalline solid to the temperature. The temperature is taken as absolute temperature.
Complete step by step answer:
It is a well-known observation that the entropy of pure substances increases with an increase in temperature because molecular motion (i.e., translational, vibrational, and rotational) increases with an increase of temperature. Conversely, entropy decreases with a decrease in temperature. In 1906, Nernst studied about the entropies of perfectly crystalline substances at absolute zero and put forward his following generalization that is known as the "third law of thermodynamics":
The entropy of perfectly crystalline solid approaches zeroes as the temperature approaches absolute zero.
In other words, we can say that the entropy of all crystalline solids may be taken as zero at the absolute zero of temperature.
Since entropy is a measure of disorder, the above definition may be given molecular interpretation as follows:
The absolute entropy is taken as zero, because at absolute zero, a perfectly crystalline solid has a perfect order of its constituent particles, i.e., there is no disorder at all.
The entropy per mole of the substance under standard conditions at the specified temperature is called standard molar entropy ($S_{m}^{\circ }$) or absolute entropy.
The absolute entropy of solids like carbon in graphite is 5.69, the carbon in diamond is 2.4, aluminium is 96.2, $CaO$ is 39.8, etc. The absolute entropy of liquids like water is 69.9, ethanol is 160.7, benzene is 159.8, etc. the absolute entropy of gases like ${{H}_{2}}$is 130.6, $N{{H}_{3}}$ is 192.5, $C{{O}_{2}}$ is 213.6, etc.
Note: The most important application of the third law of thermodynamics is the calculation of the absolute entropies of the substances at room temperature. The absolute entropy can be calculated by the formula:$S=2.303\text{ }{{\text{C}}_{p}}\log T$, where ${{C}_{p}}$ is the heat capacity at constant pressure and T is the temperature.
Complete step by step answer:
It is a well-known observation that the entropy of pure substances increases with an increase in temperature because molecular motion (i.e., translational, vibrational, and rotational) increases with an increase of temperature. Conversely, entropy decreases with a decrease in temperature. In 1906, Nernst studied about the entropies of perfectly crystalline substances at absolute zero and put forward his following generalization that is known as the "third law of thermodynamics":
The entropy of perfectly crystalline solid approaches zeroes as the temperature approaches absolute zero.
In other words, we can say that the entropy of all crystalline solids may be taken as zero at the absolute zero of temperature.
Since entropy is a measure of disorder, the above definition may be given molecular interpretation as follows:
The absolute entropy is taken as zero, because at absolute zero, a perfectly crystalline solid has a perfect order of its constituent particles, i.e., there is no disorder at all.
The entropy per mole of the substance under standard conditions at the specified temperature is called standard molar entropy ($S_{m}^{\circ }$) or absolute entropy.
The absolute entropy of solids like carbon in graphite is 5.69, the carbon in diamond is 2.4, aluminium is 96.2, $CaO$ is 39.8, etc. The absolute entropy of liquids like water is 69.9, ethanol is 160.7, benzene is 159.8, etc. the absolute entropy of gases like ${{H}_{2}}$is 130.6, $N{{H}_{3}}$ is 192.5, $C{{O}_{2}}$ is 213.6, etc.
Note: The most important application of the third law of thermodynamics is the calculation of the absolute entropies of the substances at room temperature. The absolute entropy can be calculated by the formula:$S=2.303\text{ }{{\text{C}}_{p}}\log T$, where ${{C}_{p}}$ is the heat capacity at constant pressure and T is the temperature.
Recently Updated Pages
Basicity of sulphurous acid and sulphuric acid are
Three beakers labelled as A B and C each containing 25 mL of water were taken A small amount of NaOH anhydrous CuSO4 and NaCl were added to the beakers A B and C respectively It was observed that there was an increase in the temperature of the solutions contained in beakers A and B whereas in case of beaker C the temperature of the solution falls Which one of the following statements isarecorrect i In beakers A and B exothermic process has occurred ii In beakers A and B endothermic process has occurred iii In beaker C exothermic process has occurred iv In beaker C endothermic process has occurred
What is the stopping potential when the metal with class 12 physics JEE_Main
The momentum of a photon is 2 times 10 16gm cmsec Its class 12 physics JEE_Main
How do you arrange NH4 + BF3 H2O C2H2 in increasing class 11 chemistry CBSE
Is H mCT and q mCT the same thing If so which is more class 11 chemistry CBSE
Trending doubts
Difference between Prokaryotic cell and Eukaryotic class 11 biology CBSE
Difference Between Plant Cell and Animal Cell
Fill the blanks with the suitable prepositions 1 The class 9 english CBSE
Change the following sentences into negative and interrogative class 10 english CBSE
Give 10 examples for herbs , shrubs , climbers , creepers
What organs are located on the left side of your body class 11 biology CBSE
Write an application to the principal requesting five class 10 english CBSE
What is the type of food and mode of feeding of the class 11 biology CBSE
Name 10 Living and Non living things class 9 biology CBSE