VCE Chemistry flashcards
VCE Chemistry · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Mole definition
- One mole is the amount of substance containing 6.02 × 10²³ specified particles. It links mass, particle number and gas volume through molar mass and molar volume.
- Molar volume of gas
- At standard conditions (0 °C and 100 kPa), one mole of any gas occupies 22.7 L. Thus n = V ÷ 22.7 when V is in litres at STP.
- Empirical formula
- The simplest whole-number ratio of atoms of each element in a compound. It is found by dividing each element's mole amount by the smallest amount present.
- Limiting reagent
- The reactant that is completely consumed first and therefore determines the maximum amount of product formed. Others are in excess and remain after reaction.
- Percentage yield
- Actual yield divided by theoretical yield, multiplied by 100. Losses from side reactions, incomplete reaction and transfer errors make it less than 100 percent.
- Atom economy
- Molar mass of the desired product divided by the sum of molar masses of all reactants, times 100. It measures how much reactant mass ends up in the target product.
- Concentration in mol/L
- Amount of solute in moles divided by solution volume in litres. Dilution conserves solute moles, so initial concentration times initial volume equals final concentration times final volume.
- Ionic equation
- A equation showing only the species that actually change, with spectator ions removed. Soluble strong electrolytes are written as separate ions; precipitates and weak acids stay intact.
- Oxidation and reduction
- Oxidation is loss of electrons, shown by an increase in oxidation number. Reduction is gain of electrons. The two always occur together in a redox reaction.
- Electronegativity and bonding
- Electronegativity is an atom's attraction for shared electrons. Large differences between bonded atoms give ionic character; small differences give nonpolar covalent bonding.
- VSEPR theory
- Electron domains around a central atom repel and spread as far apart as possible. This predicts molecular shape and approximate bond angles from the number of bonding and lone pairs.
- Hydrogen bonding
- A strong dipole attraction between a hydrogen atom bonded to N, O or F and a lone pair on a nearby N, O or F atom. It explains water's high boiling point.
- Exothermic reaction
- A reaction that releases energy to the surroundings, so temperature rises and enthalpy change is negative. Products have lower enthalpy than reactants; combustion is a common example.
- Bond enthalpy and enthalpy change
- Enthalpy change equals energy absorbed breaking bonds in reactants minus energy released forming bonds in products. Breaking bonds absorbs energy; forming bonds releases it.
- Avogadro's law
- Equal volumes of gases at the same temperature and pressure contain equal numbers of molecules. Therefore gas volume ratios in a balanced equation equal mole ratios.
- Precipitation reaction
- A reaction in which two solutions are mixed and an insoluble ionic solid forms. Solubility rules predict whether a precipitate such as silver chloride or barium sulfate appears.
- IUPAC naming priority
- The principal functional group with highest priority determines the suffix and the numbering of the parent chain. Carboxylic acids outrank aldehydes, ketones, alcohols and alkenes.
- Esterification reaction
- A reversible, acid-catalysed reaction between a carboxylic acid and an alcohol producing an ester and water. The ester is named as an alkyl alkanoate.
- Addition polymerisation
- Monomers containing carbon-carbon double bonds join without losing atoms, forming a long saturated chain. The polymer's repeating unit has the same empirical formula as the monomer.
- Condensation polymerisation
- Monomers with two reactive functional groups join with elimination of a small molecule such as water. Polyesters and polyamides form this way.
- Calorimetry formula
- Heat released or absorbed equals mass times specific heat capacity times temperature change. For aqueous solutions, use 4.18 J per gram per kelvin for water.
- Equilibrium constant K
- The ratio of product concentrations to reactant concentrations, each raised to its stoichiometric coefficient, at equilibrium. K changes only with temperature, not concentration or pressure.
- Le Chatelier's principle
- When a system at equilibrium is disturbed, it shifts in the direction that partly opposes the change. Concentration, pressure and temperature changes cause predictable shifts.
- pH definition
- pH equals the negative base-10 logarithm of the hydronium ion concentration in mol per litre. A change of one pH unit means a tenfold change in acidity.
- Strong versus weak acid
- A strong acid ionises completely in water, giving a high hydronium concentration. A weak acid ionises only partially and has a small acid dissociation constant.
- Titration equivalence point
- The point where the acid and base have reacted in the exact mole ratio of the balanced equation. For a monoprotic acid and base, moles of acid equal moles of base.
- Atomic absorption spectroscopy
- A technique that measures light absorbed by ground-state atoms of an element in a flame. Absorbance is compared with calibration standards to find concentration.
- Infrared spectroscopy
- Molecules absorb infrared radiation at frequencies matching their bond vibrations. The absorption pattern identifies functional groups such as O-H, C=O and C-H.
- Proton NMR spectroscopy
- Hydrogen nuclei in different chemical environments absorb at different chemical shifts. Peak area gives relative hydrogen numbers and splitting follows the n plus one rule.
- Mass spectrometry
- A sample is ionised and ions are separated by mass-to-charge ratio. The molecular ion peak gives molar mass and fragment peaks reveal structural features.
- Galvanic cell operation
- Oxidation occurs at the anode, which is the negative electrode, and reduction at the cathode, the positive electrode. Electrons travel through the external circuit.
- Standard cell potential
- Cell potential equals the cathode reduction potential minus the anode reduction potential under standard conditions. A positive value indicates a spontaneous reaction.