Ch 7Thermodynamics — Class 11 Chemistry, concept-first.

Every time a fuel burns to release heat, a circuit carries current, or a cell metabolises glucose for energy, an energy transformation is taking place -- and thermodynamics is the branch of chemistry…

'Thermodynamics' comes from the Greek thermos (heat) and dynamics (flow/movement) -- literally the flow of heat.

Before any law of thermodynamics can be stated precisely, a handful of vocabulary terms need fixing.

Thermodynamic systems are sorted into three types purely by what their boundary permits to cross it -- matter, energy, both, or neither.

A system's properties -- the measurable quantities that describe its current state -- split cleanly into two categories depending on whether they depend on how MUCH of the system you have.

Any operation that changes a system from one state to another is called a thermodynamic process -- heating, cooling, expansion, compression, fusion (melting) and vaporisation are everyday examples.

The zeroth law of thermodynamics -- also called the law of thermal equilibrium -- is a curious historical case: it was formulated and named only AFTER the first and second laws already existed, yet lo…

The first law of thermodynamics is thermodynamics' version of the law of conservation of energy: the total energy of an isolated system remains constant, no matter how many times it changes from one f…

Starting from the general first-law statement (7.7), four special cases -- each corresponding to one of the process types from Section 7.2.3 -- simplify the equation considerably.

Enthalpy, symbol , is a thermodynamic property of a system defined as the sum of its internal energy and the product of its pressure and volume: Physically, enthalpy reflects both a system's capacity…

To relate enthalpy to internal energy concretely, consider a system at constant pressure moving from an initial state (enthalpy , internal energy , volume ) to a final state (, , ).

The heat, or enthalpy, change accompanying a chemical reaction is expressed differently depending on exactly what kind of reaction (or physical change) is involved.

A thermochemical equation is simply a normal, balanced, stoichiometric chemical equation that also carries its enthalpy change alongside it.

A calorimeter is the instrument used to measure the amount of heat change accompanying a chemical or physical process.

Because and are both functions of a system's STATE, the heat evolved or absorbed by a given reaction can only depend on its initial and final states -- never on the particular path or sequence of inte…

Lattice energy, (also called lattice enthalpy), is defined as the amount of energy required to completely remove the constituent ions of one mole of a crystal from its crystal lattice, out to infinite…

The first law, on its own, only guarantees that the TOTAL energy of the universe stays conserved through any process -- it has nothing at all to say about which DIRECTION a process is allowed to run.

Entropy. The second law introduces a new state function, entropy (), as a measure of a system's molecular disorder (randomness).

A spontaneous reaction is one that runs to completion under a given set of conditions without needing any external driving force; if it cannot, it is called non-spontaneous.

Spontaneity of any process depends on three interacting factors, all of which are pulled together in the criterion at the end: - If a process's enthalpy change is NEGATIVE (exothermic), the process MA…

In a reversible chemical equilibrium, the system stays in perfect equilibrium with its surroundings at every instant, and the reaction can proceed in both the forward and reverse directions SIMULTANEO…

Entropy tracks directly with temperature: the lower the temperature, the lower a substance's entropy. Water above C, for instance, exists as a gas with relatively high entropy (high disorder) -- its m…

Sample papers and previous-year board questions for this subject.