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OpenStem
@openstem · Joined Jul 2026
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Flashcards12 cards
What makes water 'hard'?1 / 12
Dissolved calcium ions (Ca²⁺) and magnesium ions (Mg²⁺). Water picks these up as it flows over and through rock containing minerals such as limestone and chalk, which slowly dissolve into it.
Chemistry · L3 · Water Hardness
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Chemistry · L3 · Water HardnessFlashcards12 cards
What is acid rain?1 / 12
Rain (or snow) that is much more acidic than normal, caused mainly by sulfur dioxide and nitrogen oxide pollution dissolving in atmospheric water vapour to form strong acids.
Chemistry · L3 · Acid Rain
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Chemistry · L3 · Acid RainFlashcards12 cards
On a rate vs concentration graph, what does a straight line through the origin tell you about the reaction order?1 / 12
The reaction is first order in that reactant — rate is directly proportional to concentration (rate = k×[A]); doubling [A] doubles the rate.
Chemistry · L3 · Reading Rate Graphs
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Chemistry · L3 · Reading Rate GraphsFlashcards11 cards
What does Avogadro's Law state?1 / 11
Equal volumes of any gases, measured at the same temperature and pressure, contain equal numbers of particles (moles) — regardless of what the gas actually is. A litre of hydrogen and a litre of carbon dioxide, at the same temperature and pressure, hold exactly the same number of moles.
Chemistry · L3 · Avogadro's Law and Molar Gas Volume
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Chemistry · L3 · Avogadro's Law and Molar Gas VolumeFlashcards10 cards
An alcohol and a carboxylic acid are mixed together. What reaction can occur, and what two products does it give?1 / 10
Esterification: the alcohol and carboxylic acid react — usually with an acid catalyst and gentle heating — to form an ESTER plus WATER.
Chemistry · L3 · Esters — Formation and Uses
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Chemistry · L3 · Esters — Formation and UsesFlashcards12 cards
What does electronegativity measure?1 / 12
An atom's ability to attract (pull) the pair of electrons shared in a covalent bond toward itself.
Chemistry · L3 · Electronegativity and Bond Polarity
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Chemistry · L3 · Electronegativity and Bond PolarityFlashcards11 cards
What three metals act as catalysts inside a car's catalytic converter?1 / 11
Platinum, palladium and rhodium.
Chemistry · L3 · Catalysts in Industry
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Chemistry · L3 · Catalysts in IndustryFlashcards12 cards
What is a polyatomic ion, and how is it different from a monatomic ion like Cl⁻?1 / 12
A polyatomic ion is a group of atoms bonded tightly together that carries one overall charge and moves as a single unit in a formula — for example, the sulfate ion SO4²⁻ is one sulfur atom and four oxygen atoms sharing a single 2- charge between them. A monatomic ion like Cl⁻ is just one atom carrying the charge on its own.
Chemistry · L3 · Naming and Writing Ionic Formulae
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Chemistry · L3 · Naming and Writing Ionic FormulaeFlashcards10 cards
What does the retention factor, Rf, measure in chromatography?1 / 10
Rf is the ratio of how far a substance's spot travelled up the paper to how far the solvent front travelled, both measured from the same starting line. It is a single number between 0 and 1 with no units.
Chemistry · L3 · Chromatography and Rf Values
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Chemistry · L3 · Chromatography and Rf ValuesFlashcards11 cards
What is combustion analysis, in one sentence?1 / 11
An analytical technique for finding the formula of an unknown organic compound (containing only C, H, and possibly O): a known mass of the sample is burned completely in excess oxygen, and the carbon dioxide and water produced are separately trapped and weighed.
Chemistry · L3 · Combustion Analysis
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Chemistry · L3 · Combustion AnalysisFlashcards10 cards
While a substance is melting or boiling, heat keeps flowing in — so why doesn't its temperature rise?1 / 10
Because every joule of that heat is going into breaking apart the intermolecular attractions holding the particles in their current arrangement, not into speeding the particles up. Since temperature is a measure of average particle speed (kinetic energy), the thermometer doesn't move until the phase change is completely finished.
Chemistry · L3 · Specific Latent Heat
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Chemistry · L3 · Specific Latent HeatFlashcards11 cards
What fundamentally distinguishes a redox titration from an acid–base titration?1 / 11
The titrant and analyte react by transferring electrons (a redox reaction), not protons. The endpoint is also detected differently — by a redox-driven colour change rather than a pH indicator.
Chemistry · L3 · Redox Titrations
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Chemistry · L3 · Redox TitrationsFlashcards12 cards
What are the four quantum numbers that describe an electron in an atom?1 / 12
n (principal — energy level, n = 1, 2, 3, …), l (angular momentum — subshell, 0 to n−1), mₗ (magnetic — orbital orientation, −l to +l), and mₛ (spin — ±½). Together they uniquely identify an electron's state.
Chemistry · L4 · Atomic Structure & Quantum Numbers
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Chemistry · L4 · Atomic Structure & Quantum NumbersFlashcards10 cards
Distinguish ionic, covalent, and metallic bonding.1 / 10
Ionic: electron transfer between metals and non-metals → electrostatic attraction between ions. Covalent: shared electron pairs between non-metals. Metallic: delocalised electron 'sea' among metal cations. Ionic and metallic are extremes; most real bonds are polar covalent.
Chemistry · L4 · Periodicity & Chemical Bonding
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Chemistry · L4 · Periodicity & Chemical BondingFlashcards11 cards
What is a mole, and what is Avogadro's number?1 / 11
One mole is the amount of substance containing exactly 6.022 × 10²³ (Avogadro's number, Nₐ) elementary entities (atoms, molecules, ions). It links macroscopic mass to the atomic scale: 1 mol of ¹²C = 12.000 g.
Chemistry · L4 · Stoichiometry — Moles, Equations & Reactions
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Chemistry · L4 · Stoichiometry — Moles, Equations & ReactionsFlashcards11 cards
Name the six major functional groups in organic chemistry and give an example of each.1 / 11
Alcohol (–OH, ethanol), Aldehyde (–CHO, ethanal), Ketone (C=O flanked by C, propanone), Carboxylic acid (–COOH, ethanoic acid), Amine (–NH₂, methylamine), Ester (–COO–, ethyl ethanoate). Recognition of these is foundational.
Chemistry · L4 · Organic Chemistry — Functional Groups & Reactions
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Chemistry · L4 · Organic Chemistry — Functional Groups & ReactionsFlashcards11 cards
What is enthalpy change (ΔH) and how do you classify a reaction as exothermic or endothermic?1 / 11
ΔH = H_products − H_reactants (at constant pressure). Exothermic: ΔH < 0 (releases heat, e.g. combustion). Endothermic: ΔH > 0 (absorbs heat, e.g. dissolving NH₄NO₃). ΔH is independent of path (Hess's law).
Chemistry · L4 · Thermochemistry & Chemical Equilibrium
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Chemistry · L4 · Thermochemistry & Chemical EquilibriumFlashcards10 cards
What is a standard reduction potential (E°), and what counts as 'standard conditions'?1 / 10
E° is the voltage of a half-reaction, written as a reduction, measured against the standard hydrogen electrode (SHE, defined as exactly 0.00 V) under standard conditions: 1 M ion concentrations, 1 atm gas pressure, 25 °C. A more positive E° means a stronger pull on electrons — a better oxidising agent.
Chemistry · L4 · Electrochemistry: Standard Potentials & Cell Calculations
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Chemistry · L4 · Electrochemistry: Standard Potentials & Cell CalculationsFlashcards12 cards
What is a coordination complex?1 / 12
A central metal ion (usually a transition metal) surrounded by a fixed number of ligands — molecules or ions that donate an electron pair to the metal. The metal acts as a Lewis acid, the ligands as Lewis bases.
Chemistry · L4 · Coordination Chemistry
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Chemistry · L4 · Coordination ChemistryFlashcards10 cards
What is the van't Hoff factor i, and why does it appear in every colligative-property equation?1 / 10
i is the number of dissociated particles one formula unit of solute produces in solution. Colligative properties depend on total particle count, not solute identity, so every equation multiplies the 'per-mole' effect by i to account for solutes that split into multiple ions. Nonelectrolytes (glucose, sucrose, urea) have i = 1 — they don't dissociate.
Chemistry · L4 · Freezing Point Depression & Boiling Point Elevation
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Chemistry · L4 · Freezing Point Depression & Boiling Point ElevationFlashcards8 cards
State Raoult's law for the vapor pressure of the solvent above an ideal solution.1 / 8
P_solution = X_solvent · P°_solvent, where X_solvent is the mole fraction of solvent in the solution and P°_solvent is the vapor pressure of the pure solvent at that temperature. Dissolving a non-volatile solute always lowers X_solvent below 1, so P_solution < P°_solvent.
Chemistry · L4 · Raoult's Law & Osmotic Pressure
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Chemistry · L4 · Raoult's Law & Osmotic PressureFlashcards12 cards
What is the solubility product constant, Ksp?1 / 12
Ksp is the equilibrium constant for the dissolution of a sparingly-soluble ionic solid into its constituent aqueous ions: MX(s) ⇌ M⁺(aq) + X⁻(aq), Ksp = [M⁺][X⁻]. The solid is omitted (pure solid, activity = 1). A larger Ksp means a more soluble compound, though comparing Ksp values directly across different stoichiometries can be misleading.
Chemistry · L4 · Solubility Equilibria (Ksp)
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Chemistry · L4 · Solubility Equilibria (Ksp)Flashcards10 cards
What two quantities define a dipole moment, and why is it a vector?1 / 10
Magnitude (μ = Q·d — the separated charge times the distance between the charges, in debye D) AND direction (from the partial positive end toward the partial negative end). Because it has both, bond dipoles must be added head-to-tail as vectors, not just summed as magnitudes.
Chemistry · L4 · Intermolecular Forces & Molecular Polarity
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Chemistry · L4 · Intermolecular Forces & Molecular PolarityFlashcards8 cards
How do you classify an alcohol as primary, secondary, or tertiary?1 / 8
By how many carbon groups are attached to the OH-bearing carbon: primary (1°) has one, secondary (2°) has two, tertiary (3°) has three. Ethanol is 1°, isopropanol is 2°, tert-butanol is 3°.
Chemistry · L4 · Organic Chemistry II — The Oxidation Ladder
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Chemistry · L4 · Organic Chemistry II — The Oxidation LadderFlashcards7 cards
Ethanoic acid has pKa ≈ 4.8; ethanol has pKa ≈ 16. Why is the carboxylic acid's O–H so much more acidic?1 / 7
Deprotonating the carboxylic acid gives a carboxylate ion (RCOO⁻) whose negative charge is delocalized by resonance over two equivalent C–O bonds. Deprotonating the alcohol gives an alkoxide (RO⁻) with the charge stuck on a single oxygen — far less stable, so the alcohol holds onto its proton much more tightly.
Chemistry · L4 · Organic Chemistry II — Carboxylic Acid Strength & Esterification
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Chemistry · L4 · Organic Chemistry II — Carboxylic Acid Strength & EsterificationFlashcards10 cards
What three structural criteria must a ring system meet to be aromatic?1 / 10
It must be cyclic, planar, and have a continuous (fully conjugated) ring of p orbitals overlapping all the way around — with the right number of π electrons to satisfy Hückel's rule. Miss any one of these (a non-planar ring, a broken conjugation path, or the wrong electron count) and the ring is not aromatic.
Chemistry · L4 · Aromatic Chemistry & EAS
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Chemistry · L4 · Aromatic Chemistry & EASFlashcards11 cards
What makes a carbon atom a chiral (stereo)centre?1 / 11
It is bonded to four different substituent groups. Because no two of the four groups are identical, the atom cannot be superimposed on its own mirror image by any rotation.
Chemistry · L4 · Stereochemistry: Chirality, Enantiomers & R/S
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Chemistry · L4 · Stereochemistry: Chirality, Enantiomers & R/SFlashcards7 cards
State the exponential decay law and define every symbol in it.1 / 7
N(t) = N₀e^(-λt). N₀ is the number of radioactive nuclei (or activity) at t = 0, N(t) is the number remaining after time t, and λ is the decay constant — the fixed probability of decay per unit time for a single nucleus (units: inverse time).
Chemistry · L4 · Nuclear Chemistry — The Decay Law & Radiometric Dating
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Chemistry · L4 · Nuclear Chemistry — The Decay Law & Radiometric DatingFlashcards7 cards
What is mass defect (Δm)?1 / 7
The difference between the sum of the masses of a nucleus's separate, free protons and neutrons and the actual (smaller) mass of the bound nucleus. It's the mass that seems to be 'missing' once the nucleons are bound together.
Chemistry · L4 · Nuclear Chemistry — Mass Defect & Binding Energy
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Chemistry · L4 · Nuclear Chemistry — Mass Defect & Binding EnergyFlashcards8 cards
What are the four main classes of crystalline solid, classified by what holds their particles together?1 / 8
Ionic (electrostatic attraction between ions), molecular (weak intermolecular forces between discrete molecules), covalent network (one giant, continuously covalently-bonded lattice), and metallic (a delocalized 'sea' of electrons shared among metal cations).
Chemistry · L4 · Solid State Chemistry — Crystal Classes & Bonding
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Chemistry · L4 · Solid State Chemistry — Crystal Classes & Bonding