CBSE Class 11 Chemistry Flashcards

24 sample cards from the Chemistry deck

Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.

1. Distinguish open, closed, and isolated systems.

   Open system: exchanges both matter and energy with surroundings. Closed system: exchanges only energy, not matter. Isolated system: exchanges neither matter nor energy (e.g., thermos flask).

2. Define isothermal, adiabatic, isobaric, and isochoric processes.

   Isothermal: constant temperature (ΔT = 0). Adiabatic: no heat exchange (q = 0). Isobaric: constant pressure (ΔP = 0). Isochoric: constant volume (ΔV = 0).

3. State the First Law of Thermodynamics and its mathematical form.

   Energy can neither be created nor destroyed, only converted from one form to another (conservation of energy). Mathematically: ΔU = q + w, where ΔU is change in internal energy, q is heat added, and w is work done on the system.

4. Define enthalpy (H) and write the relation between ΔH and ΔU.

   Enthalpy is the total heat content of a system at constant pressure, H = U + PV. The relation is ΔH = ΔU + Δ(PV); for reactions involving gases, ΔH = ΔU + Δng RT.

5. Define heat capacity, and distinguish Cp and Cv.

   Heat capacity is the heat required to raise the temperature of a substance by 1 degree. Cv is heat capacity at constant volume; Cp is at constant pressure. For an ideal gas, Cp - Cv = R.

6. What is dynamic equilibrium in a physical or chemical process?

   A state at which the rate of the forward process equals the rate of the reverse process, so the concentrations of reactants and products remain constant while both processes continue at the molecular level.

7. State the law of chemical equilibrium and write the equilibrium constant expression for aA + bB ⇌ cC + dD.

   At equilibrium, the ratio of the product of molar concentrations of products to that of reactants, each raised to its stoichiometric coefficient, is constant. Kc = ([C]^c[D]^d)/([A]^a[B]^b).

8. What is the relationship between Kp and Kc?

   Kp = Kc(RT)^Δng, where Δng is the change in the number of moles of gas (moles of gaseous products minus moles of gaseous reactants).

9. State Le Chatelier's principle and how pressure affects equilibrium.

   If a system at equilibrium is subjected to a change in concentration, temperature, or pressure, the equilibrium shifts to counteract the change. Increasing pressure shifts equilibrium toward the side with fewer gaseous moles.

10. How do temperature and a catalyst affect chemical equilibrium?

    Increasing temperature shifts equilibrium in the endothermic direction (and changes K). A catalyst does not shift the equilibrium position or change K; it only speeds up the attainment of equilibrium by lowering activation energy for both directions equally.

11. Define oxidation and reduction in terms of electrons and oxidation number.

    Oxidation: loss of electrons / increase in oxidation number. Reduction: gain of electrons / decrease in oxidation number. (Mnemonic: OIL RIG — Oxidation Is Loss, Reduction Is Gain.)

12. What is a redox reaction, and identify the oxidising and reducing agents?

    A redox reaction is one in which oxidation and reduction occur simultaneously. The oxidising agent gets reduced (gains electrons); the reducing agent gets oxidised (loses electrons).

13. Why does hydrogen have an anomalous position in the periodic table?

    Hydrogen resembles both alkali metals (group 1, one valence electron, forms H+) and halogens (group 17, one electron short of a noble gas, forms H-). Hence its position is anomalous; it is usually placed in group 1.

14. What are the three isotopes of hydrogen?

    Protium (1H1, no neutron), Deuterium (1H2 or D, one neutron), and Tritium (1H3 or T, two neutrons; radioactive).

15. Classify hydrides into their three main types with examples.

    Ionic (saline) hydrides — with s-block metals, e.g., NaH, CaH2. Covalent (molecular) hydrides — with p-block elements, e.g., CH4, H2O, NH3. Metallic (interstitial) hydrides — with d- and f-block elements, e.g., some transition metal hydrides.

16. What is the general electronic configuration and key properties of Group 1 alkali metals?

    General configuration ns1. They are soft, highly reactive metals with low ionization enthalpy, low density, and +1 oxidation state. Reactivity increases down the group (Li, Na, K, Rb, Cs, Fr).

17. What is the general electronic configuration of Group 2 alkaline earth metals and how do they differ from alkali metals?

    General configuration ns2; they exhibit +2 oxidation state. Compared to alkali metals, they are harder, denser, have higher melting points, higher ionization enthalpy, and are less reactive.

18. What is the general electronic configuration of p-block elements and which groups do they include?

    p-block elements have the general configuration ns2 np1-6 and include groups 13 to 18 (boron, carbon, nitrogen, oxygen, halogen, and noble gas families).

19. Name common methods used for purification of organic compounds.

    Sublimation, crystallisation, distillation (simple, fractional, under reduced pressure, steam), differential extraction, and chromatography.

20. What is the difference between qualitative and quantitative analysis of organic compounds?

    Qualitative analysis detects which elements (C, H, N, S, halogens, etc.) are present in an organic compound. Quantitative analysis determines the percentage/amount of each element present.

21. State the basic rules for IUPAC nomenclature of an organic compound.

    Identify the longest carbon chain (parent), number it to give lowest locants to substituents/functional groups, name substituents as prefixes (in alphabetical order) with locants, and add the suffix for the principal functional group. Format: locant-prefix + root + suffix.

22. Define inductive effect, resonance, and hyperconjugation as electronic displacements in covalent bonds.

    Inductive effect: permanent partial shift of sigma-bond electrons due to electronegativity difference. Resonance (mesomeric) effect: delocalisation of pi/lone-pair electrons giving multiple canonical structures. Hyperconjugation: delocalisation of sigma (C-H) electrons into an adjacent empty/p orbital, stabilising the system.

23. How are hydrocarbons classified?

    Hydrocarbons are classified as: (1) Saturated (alkanes, only single bonds), (2) Unsaturated (alkenes with C=C and alkynes with C≡C), and (3) Aromatic (containing benzene ring/cyclic delocalised pi systems). Acyclic (open chain) and cyclic categories also apply.

24. Name major air pollutants and one harmful effect of each.

    CO2 — global warming/greenhouse effect; CO — reduces oxygen-carrying capacity of blood; SO2 and NOx — acid rain and respiratory problems; CFCs — ozone layer depletion; particulate matter — respiratory diseases.

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