Senior Secondary Chemistry and Physics Comprehensive Review

Comprehensive practice flashcards covering Senior Secondary 2 (SS2) Chemistry topics including water treatment and hardness, solubility dynamics, organic reaction mechanisms and nomenclature (alkanes, alkenes, alkynes, benzene, alkanols), acid-base equilibrium, qualitative analysis, and basic vector mechanics.

What is the active disinfecting agent formed during the chlorination stage of municipal water treatment?

Hypochlorous acid ($\text{HOCl}$), formed by the reaction $\text{OCl}^- + \text{H}_2\text{O} \rightarrow \text{HOCl} + \text{OH}^-$.

What bond angle and net dipole moment are associated with the bent geometry of a water molecule?

A bond angle of $104.5^\circ$ and a net dipole moment of $1.84\,\text{D}$.

What causes the formation of limescale inside kettles and hot water boilers when heating hard water?

The thermal decomposition of soluble calcium hydrogencarbonate into insoluble calcium carbonate: $\text{Ca}(\text{HCO}_3)_2 \rightarrow \text{CaCO}_3\downarrow + \text{H}_2\text{O} + \text{CO}_2$.

How is permanent hardness removed from water using the Permutit (ion-exchange) method?

Hard water containing $\text{Ca}^{2+}$ or $\text{Mg}^{2+}$ is passed through a column containing sodium zeolite ($\text{Na}_2\text{Al}_2\text{Si}_2\text{O}_8 \cdot x\text{H}_2\text{O}$), where $\text{Ca}^{2+}$ and $\text{Mg}^{2+}$ ions replace the $\text{Na}^+$ ions on the resin.

According to the solubility curve of six solutes in water, which solute exhibits the highest solubility at $0^\circ\text{C}$, and which has the highest solubility at $100^\circ\text{C}$?

$\text{NaNO}_3$ has the highest solubility at $0^\circ\text{C}$, while $\text{KNO}_3$ has the highest solubility at $100^\circ\text{C}$.

What is catenation in organic chemistry, and which other elements possess this ability?

Catenation is the ability of identical atoms (particularly carbon) to bond together into long straight chains, branched chains, or rings. Other elements that can catenate include boron, silicon, and sulphur.

What reaction and apparatus setup are used for the laboratory preparation of methane gas?

Heating a mixture of anhydrous sodium ethanoate ($\text{CH}_3\text{COONa}$) and soda lime ($\text{NaOH}/\text{CaO}$) in a hard glass flask, collecting the gas over water: $\text{CH}_3\text{COONa}_{(s)} + \text{NaOH}_{(s)} \rightarrow \text{Na}_2\text{CO}_{3(s)} + \text{CH}_{4(g)}$.

What is the role of the sodium hydroxide wash bottle in the laboratory preparation of ethene by dehydration of ethanol?

It removes acidic gaseous impurities, specifically sulphur(IV) oxide ($\text{SO}_2$) and carbon(IV) oxide ($\text{CO}_2$), produced by the reduction of hot concentrated $\text{H}_2\text{SO}_4$.

How is ethyne gas prepared in the laboratory, and why is the gas passed through acidified copper(II) sulphate solution?

By dropping cold water onto calcium dicarbide ($\text{CaC}_2 + 2\text{H}_2\text{O} \rightarrow \text{Ca}(\text{OH})_2 + \text{C}_2\text{H}_2$); acidified $\text{CuSO}_4$ absorbs phosphine ($\text{PH}_3$) impurity.

What chemical test distinguishes terminal alkynes like ethyne from alkanes and alkenes?

Passing the gas through ammoniacal copper(I) chloride solution produces a reddish-brown precipitate of copper(I) dicarbide ($\text{Cu}_2\text{C}_2$), and ammoniacal silver trioxonitrate(V) produces a yellowish-white precipitate of silver dicarbide ($\text{Ag}_2\text{C}_2$).

Why does benzene primarily undergo substitution reactions rather than addition reactions despite having three formal double bonds?

The six $\pi$-electrons are delocalized evenly across the planar ring rather than localized between specific carbon atoms; substitution preserves the stable aromatic resonance structure, whereas addition destroys it.

What is the sequence of enzymes involved in converting starch from sweet potato into ethanol during fermentation?

1. Diastase (in malt) hydrolyses starch to maltose.\n2. Maltase (in yeast) hydrolyses maltose to glucose.\n3. Zymase (in yeast) converts glucose to ethanol and $\text{CO}_2$.

What is an oxonium ion?

The hydrated proton species ($\text{H}_3\text{O}^+$) formed when a hydrogen ion bonds covalently via a coordinate bond to a water molecule.

What is a deliquescent substance, and what are two common examples?

A substance that absorbs moisture from the atmosphere and dissolves in it to form a solution, such as solid potassium hydroxide ($\text{KOH}$) and sodium hydroxide ($\text{NaOH}$).

What is the chemical name and formula of washing soda in its decahydrate form?

Sodium trioxocarbonate(IV) decahydrate, with the formula $\text{Na}_2\text{CO}_3 \cdot 10\text{H}_2\text{O}$.

A toy is pulled horizontally on a smooth surface by a rope inclined at an angle of $60^\circ$. If the horizontal force component is $5\,\text{N}$, what is the tension $T$ in the rope?

$T = \frac{5}{\cos(60^\circ)} = \frac{5}{0.5} = 10\,\text{N}$.

What is the formula for the maximum height $h$ reached by a projectile launched with initial velocity $u$ at an angle $\theta$ to the horizontal?

$h = \frac{u^2 \sin^2(\theta)}{2g}$.

What is the conjugate base of tetraoxosulphate(VI) acid ($\text{H}_2\text{SO}_4$) according to the Brønsted-Lowry theory?

Hydrogen tetraoxosulphate(VI) ion ($\text{HSO}_4^-$).

What is the pH of a $0.001\,\text{mol}\,\text{dm}^{-3}$ solution of strong acid $\text{HCl}$ at $25^\circ\text{C}$?

$\text{pH} = -\log_{10}[\text{H}^+] = -\log_{10}(10^{-3}) = 3$.

What volume of $0.1\,\text{mol}\,\text{dm}^{-3}\,\text{NaOH}$ is required to neutralise $25\,\text{cm}^3$ of $0.2\,\text{mol}\,\text{dm}^{-3}\,\text{HCl}$?

$50\,\text{cm}^3$, determined from $\frac{C_a V_a}{C_b V_b} = \frac{1}{1} \Rightarrow V_b = \frac{0.2 \times 25}{0.1} = 50\,\text{cm}^3$.

Which common substance is applied in agriculture to neutralise overly acidic soil?

Calcium carbonate ($\text{CaCO}_3$) or limestone/slaked lime.

Why does an aqueous solution of ammonium chloride ($\text{NH}_4\text{Cl}$) test acidic to litmus?

Because it undergoes cationic hydrolysis: $\text{NH}_4^+ + \text{H}_2\text{O} \rightleftharpoons \text{NH}_3 + \text{H}_3\text{O}^+$, producing excess hydroxonium ions in solution.

What colour change does phenolphthalein indicator undergo in an alkaline solution?

It changes from colourless to pink (or red).

What makes zinc oxide ($\text{ZnO}$) and aluminium oxide ($\text{Al}_2\text{O}_3$) amphoteric oxides?

They can react with both acids (forming a salt and water) and strong bases (forming complex salts).