Thermodynamics Class 11| Lec - 2| NEET Chemistry Syllabus 2025 | Aarambh Series | Nitesh Devnani

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Lecture Two of Thermodynamics covers topics like system, internal energy, First Law, and different types of processes, alongside formulae and planner for NBDS tests provided. Additionally, the discussion includes molar heat capacity, gas properties, and specific heat calculations for different substances.

Insights

  • Internal energy is a state function that excludes gravitational energy, calculated as the sum of all energies in a system, and remains constant in an isothermal process, leading to the equation ΔU = Q - W.
  • Enthalpy, defined as the sum of internal energy and pressure-volume energy, has two forms of the formula based on constant pressure and volume, with the general formula being Delta H = Delta Y + Delta P, providing insight into heat exchange and energy changes in different processes.

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Recent questions

  • What is the concept of internal energy?

    Internal energy is the sum of all energies in a system.

  • What is the First Law of Thermodynamics based on?

    The First Law is based on the conservation of energy.

  • What is the significance of the isothermal process?

    In an isothermal process, internal energy remains constant.

  • What is enthalpy and its relation to internal energy?

    Enthalpy is the sum of internal energy and pressure-volume energy.

  • What is heat capacity and its significance in thermodynamics?

    Heat capacity is the amount of heat needed to raise the temperature of a substance.

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Summary

00:00

Thermodynamics Lecture: Formulas, Energy, Conservation, Equilibrium

  • Lecture Two of Thermodynamics is starting today, focusing on formulas and new terms.
  • A planner for NBDS tests is provided, including topics like Thermodynamics and Equilibrium.
  • Instructions are given to stick the planner on the wall for test preparation.
  • The lecture covers topics like system, boundary, state function, path function, and types of processes.
  • The concept of internal energy is introduced, represented by Y or e, as the sum of all energies in a system.
  • Gravitational energy is excluded from internal energy calculations due to negligible mass.
  • Internal energy is a state function, calculated as the change between initial and final internal energy.
  • The First Law of Thermodynamics is explained, based on the conservation of energy.
  • Different forms of the First Law are discussed, including the isothermal process and cyclic processes.
  • In an isothermal process, internal energy remains constant, leading to the equation ΔU = Q - W.

15:48

State Functions and Energy in Thermodynamics

  • Change in State Function is Zero
  • Internal energy is a state function
  • Isothermal process maintains the same expression
  • Adiabatic process has zero heat exchange
  • Expansion work is negative, internal energy decreases
  • Compression work is positive, internal energy increases
  • Isochoric process has constant volume, work done is zero
  • Heat at constant volume is crucial for internal energy
  • Isobaric process has constant pressure, work done is related to enthalpy
  • Enthalpy is the sum of internal energy and pressure-volume energy

32:37

Enthalpy and Ideal Gas Equations Explained

  • General formula: Delta H = Delta Y + Delta P
  • Two forms of the formula: one for constant pressure, one for constant volume
  • Constant pressure form: Delta H = Delta Y + P Delta V
  • Constant volume form: Delta H = Delta Y + Volume (V) taken out
  • Middle formula useful in cases at 95
  • Enthalpy definition: heat released and absorbed at constant pressure
  • Ideal Gas Equation: P, V, moles, heat relationship
  • Delta NG calculation: sum of gaseous moles in product minus reactant
  • Example: NH3 to N2 + 3H2, Delta NG = 2
  • Example: CO2 to C + O2, Delta NG = 1
  • Formula: Delta H = Delta U + P Delta V, can replace P Delta V with Delta NG RT from Ideal Gas Equation

49:23

Understanding Heat Capacity and Molar Heat

  • The first case discussed is when the delta energy becomes zero, leading to delta H and delta Y becoming equal.
  • In the second case, if delta NG is greater than zero, resulting in a positive term, delta H will be larger than delta Y.
  • The third case involves delta NG being zero, indicating a negative term, causing delta H to decrease while delta Y increases.
  • Heat capacity is defined as the amount of heat needed to raise the temperature of a substance by one degree or one Kelvin.
  • Specific heat capacity represents the heat required to raise the temperature of one gram of a substance by one degree or one Kelvin.
  • Molar heat capacity, represented by CM, is the heat needed to raise the temperature of one mole of a substance by one degree or one Kelvin.
  • Molar heat capacity has two types: constant volume (CV) and constant pressure (C).
  • Meyer's formula, Seep - Seeb = nR, is used for molar heat capacity calculations.
  • Gamma, also known as Poisson's Ratio, is calculated as the ratio of Si to Ba.
  • The table of gas properties indicates that for monoatomic gases like helium and neon, the value of CV is 3R.

01:06:24

Calculating Specific Heat in Thermodynamics Systems

  • To calculate the specific heat at constant volume (CV) in 3R, look at the Meyers formula and find that CP - CV equals R.
  • For CP1, add the CV PS value to the existing CV. The result is 5 Aaa Batu.
  • The value of Gamma is 1.4, obtained by dividing 7 by 5 Aaa Batu.
  • Triatomic molecules consist of three atoms in a linear arrangement, like CO2, while non-linear triatomic molecules, such as SO2, have a different structure.
  • Polyatomic molecules, regardless of the number of atoms they contain, have a CV of 3 Aa Si P and a CP of 4 Aa Bath 1.33.
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