Year 13 Chemistry Flashcards

Comprehensive practice flashcards for Year 13 Chemistry covering General Chemistry, Investigating Matter, Physical Chemistry, Materials, and Consumer Chemistry.

What is the difference between interpolation and extrapolation when analyzing graphical data?

Interpolation is estimating unmeasured data points within the range of plotted known data points, whereas extrapolation is predicting data points beyond the range of known data by extending the line of best fit.

What laboratory apparatus setup is shown in this diagram, and what is its primary function?

It shows a reflux setup, which is used to heat a reaction mixture with a boiling solvent while continuously condensing and returning volatile vapours to the reaction vessel to increase product yield without losing solvent.

How is the percentage atom economy of a chemical reaction calculated?

$$\text{Atom Economy} = \frac{\text{Molecular weight of desired product}}{\text{Sum of molecular weights of all substances produced}} \times 100$$

What is the principal quantum number ($n$) and what does it describe?

The principal quantum number ($n$) designates the main electron shell or energy level, describing the energy of an electron and its average distance from the nucleus.

What are the three key rules governing the arrangement of electrons in atomic orbitals?

The Aufbau Principle states that electrons fill lowest energy orbitals first; Hund's Rule states that degenerate orbitals are filled singly before pairing; and the Pauli Exclusion Principle states no two electrons in an atom can have the same set of four quantum numbers.

What orbital filling principle is illustrated in this diagram?

The Aufbau Principle, which shows the order in which atomic orbitals are filled from lowest to highest energy ($1s \rightarrow 2s \rightarrow 2p \rightarrow 3s \rightarrow 3p \rightarrow 4s \rightarrow 3d \dots$).

What is the ground-state electron configuration of chromium ($Cr$, $Z = 24$) and copper ($Cu$, $Z = 29$)?

Chromium is $[\text{Ar}]\,3d^5\,4s^1$ and copper is $[\text{Ar}]\,3d^{10}\,4s^1$, as half-filled ($3d^5$) and fully-filled ($3d^{10}$) $d$ subshells provide extra thermodynamic stability.

Why is a cation smaller than its parent neutral atom, whereas an anion is larger than its parent neutral atom?

Cations lose electrons, decreasing electron-electron repulsion and increasing net nuclear pull per electron; anions gain electrons, increasing electron-electron repulsion and expanding the electron cloud.

What type of covalent bond formation is depicted in this orbital overlap diagram?

A pi ($\pi$) bond, formed by the sideways overlap of two parallel $p$ atomic orbitals.

What is a dative (coordinate covalent) bond?

A dative bond is a covalent bond in which both shared electrons in the bonding pair are donated by a single atom possessing a lone pair into an empty orbital of another atom.

What are the main postulates of the Kinetic Theory of Gases?

Gases consist of particles in constant random motion with negligible volume relative to total volume; intermolecular forces are negligible; collisions are perfectly elastic; and average kinetic energy is directly proportional to absolute temperature in Kelvin.

What is the mathematical statement of the Ideal Gas Law?

$P V = n R T$, where $P$ is pressure, $V$ is volume in $dm^3$ or $cm^3$, $n$ is moles of gas, $R$ is the universal gas constant ($8.314\,\text{J\,K}^{-1}\,\text{mol}^{-1}$), and $T$ is temperature in Kelvin.

How is the molality ($m$) of a solution defined and calculated?

$\text{Molality } (m) = \frac{\text{Moles of solute } (\text{mol})}{\text{Mass of solvent } (\text{kg})}$, expressed in units of $mol\,\text{kg}^{-1}$.

What is the difference between an oxidising agent (oxidant) and a reducing agent (reductant)?

An oxidising agent causes another substance to be oxidised by accepting electrons and being reduced itself (oxidation number decreases); a reducing agent causes another substance to be reduced by donating electrons and being oxidised itself (oxidation number increases).

What electrochemical setup is shown in this diagram, and what reaction occurs at the anode?

A galvanic cell ($\text{Cu}/\text{Cu}^{2+} \parallel \text{Ag}^+/\text{Ag}$), where oxidation of copper metal occurs at the anode ($\text{Cu}(s) \rightarrow \text{Cu}^{2+}(aq) + 2e^-$) and reduction of silver ions occurs at the cathode ($\text{Ag}^+(aq) + e^- \rightarrow \text{Ag}(s)$).

How is the standard cell potential ($E^\circ_{\text{cell}}$) calculated from standard reduction potentials?

$E^\circ_{\text{cell}} = E^\circ_{\text{reduction}}(\text{cathode}) - E^\circ_{\text{reduction}}(\text{anode})$; a positive $E^\circ_{\text{cell}}$ indicates a spontaneous redox reaction under standard conditions.

What type of reaction energy profile is shown in this diagram, and what is the sign of $\Delta H$?

An exothermic reaction profile, where the enthalpy of products is lower than the enthalpy of reactants, resulting in a negative enthalpy change ($\Delta H < 0$) as heat is released to the surroundings.

What equation is used to calculate heat energy ($H$) absorbed or released during calorimetry?

$H = m \times c \times \Delta T$, where $m$ is mass, $c$ is specific heat capacity, and $\Delta T$ is the temperature change ($T_{\text{final}} - T_{\text{initial}}$).

What is Hess's Law of Constant Heat Summation?

Hess's Law states that the total enthalpy change for a chemical reaction is independent of the pathway or number of steps taken, depending only on the initial reactants and final products.

How is the enthalpy change of a reaction calculated from average bond energies?

$\Delta H^\circ = \sum \Delta H(\text{bonds broken in reactants}) - \sum \Delta H(\text{bonds formed in products})$.

What is the expression for the acid dissociation constant ($K_a$) of a weak acid $\text{HA}(aq) + \text{H}_2\text{O}(l) \rightleftharpoons \text{A}^-(aq) + \text{H}_3\text{O}^+(aq)$?

$K_a = \frac{[\text{A}^-][\text{H}_3\text{O}^+]}{[\text{HA}]}$; a larger $K_a$ (or smaller $p K_a$) indicates a stronger acid.

What relationship connects $K_a$, $K_b$, and $K_w$ for a conjugate acid-base pair at $25\,^\circ\text{C}$?

$K_a \times K_b = K_w = 1.0 \times 10^{-14}$ at $25\,^\circ\text{C}$, or in logarithmic form: $p K_a + p K_b = p K_w = 14$.

What type of acid-base titration is represented by this titration curve, and what is the expected pH at equivalence?

A weak acid titrated with a strong base (such as $\text{CH}_3\text{COOH}$ with $\text{NaOH}$), resulting in an equivalence point at $\text{pH} > 7$ due to the basic nature of the conjugate base formed.

What criteria determine whether a precipitate will form when two ionic solutions are mixed?

A precipitate forms if the ionic product ($IP$) exceeds the solubility product constant ($K_{sp}$) for the salt ($IP > K_{sp}$).

What is the Common-Ion Effect on the solubility of a sparingly soluble salt?

The addition of a soluble salt sharing a common ion with a sparingly soluble salt shifts the solubility equilibrium toward the solid reactant according to Le Chatelier's principle, decreasing the salt's solubility.

How do ionic hydrides differ from covalent hydrides in their bonding and reaction with water?

Ionic hydrides (e.g., $\text{NaH}$) contain hydride anions ($\text{H}^-$) in ionic lattices and react violently with water to form basic hydroxide solutions and $\text{H}_2(g)$; covalent hydrides (e.g., $\text{HCl}$, $\text{CH}_4$) involve shared electron pairs with non-metals.

What characteristic chemical properties distinguish transition metals from main-group metals?

Transition metals exhibit variable oxidation states, form coloured complex ions, exhibit paramagnetism due to unpaired $d$ electrons, and act as effective catalysts.

What is Markovnikov's Rule regarding the addition of hydrogen halides to unsymmetrical alkenes?

In the electrophilic addition to an unsymmetrical alkene, the hydrogen atom attaches to the double-bonded carbon atom that already possesses the greater number of hydrogen atoms.

Why does benzene ($\text{C}_6\text{H}_6$) undergo electrophilic substitution rather than addition reactions?

Benzene possesses a delocalised $\pi$-electron ring providing high resonance stabilization energy; addition reactions would disrupt this aromatic stabilization, whereas substitution preserves it.

What is the order of priority for naming organic functional groups from highest to lowest?

Carboxylic acids > Esters > Acyl chlorides > Amides > Aldehydes > Ketones > Alcohols > Amines > Alkenes > Alkynes > Alkanes > Ethers > Alkyl halides.

What reaction process is illustrated in this diagram?

Condensation polymerisation forming a polyester from ethylene glycol and terephthalic acid, releasing water ($\text{H}_2\text{O}$) as a byproduct.

How do addition polymers differ from condensation polymers in their formation?

Addition polymers form by direct joining of unsaturated monomer units (containing $\text{C}=\text{C}$ bonds) without losing any atoms, whereas condensation polymers form by linking polyfunctional monomers with the elimination of small molecules like $\text{H}_2\text{O}$.