Chemistry Exam Review

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Questions and Answers

Which one of the following orbitals is filled with electron in the ground state hydrogen atom?

None of these

p orbital

s orbital (correct)

Which process is an oxidation?

Mg = Mg+ + 2e- (correct)

H₂ = 2H

Na = Na+ + e- (correct)

NaCl + AgNO₃ = AgCl + NaNO₃

Zn+ 2e- = Zn

What is the maximum number of electrons on an L shell?

8 (correct)

Which one is a primary bond type?

Ionic bond Signup and view all the answers

Brønsted bases are...

Proton acceptors Signup and view all the answers

Solution A has a pH = 1, and solution B has a pH = 2. This means the concentration of H+ ions is...

10 times higher in solution A than solution B Signup and view all the answers

Define "boiling point"

The temperature at which a liquid boils and turns into gas. The boiling point temperature may vary, depending on the element. The vapor pressure of the liquid is equal to the external pressure. Signup and view all the answers

Define the density of a solution. What is the unit of density? Is it an extensive or an intensive property?

Density is the mass of a substance per unit volume. It's an intensive property. Density can be used to identify substances and is independent of the amount of the substance. The unit of density is g/dm3. Signup and view all the answers

Define the Gibbs free energy with formula!

The Gibbs free energy (G) is a thermodynamic quantity that represents the amount of energy available to do useful work in a system at constant temperature and pressure. It is calculated by subtracting the product of temperature (T) and entropy (S) from enthalpy (H): G = H - TS Signup and view all the answers

What is micelle? Write an example for a material that builds up micelle.

A micelle is a spherical structure formed in solution by the self-assembly of amphiphilic molecules composed of hydrophilic heads and hydrophobic tails. An example is soap. Soap molecules are amphiphilic and form micelles in water, with their hydrophobic tails facing inwards and their hydrophilic heads facing outwards. Signup and view all the answers

What does "ligand" mean in complexometry? What are the common properties of ligands? Write two examples for ligands.

A ligand is a molecule or ion that binds to a metal atom by coordinate bonding. Common properties of ligands include having a lone pair of electrons available for donation to the metal atom, being able to form complex ions, and having a variety of shapes and sizes. Two examples of ligands are ammonia (NH3) and water (H2O). Signup and view all the answers

Write the ideal gas law, and name the symbols

PV = nRT, where P = pressure, V = volume, n = number of moles, R = gas constant, and T = temperature. Signup and view all the answers

What does the "delocalized" bond mean? Show an ion or a molecule contains delocalized bond!

A delocalized bond is a type of chemical bond where electrons are not confined to a single pair of atoms but rather spread out over multiple atoms or even the entire molecule. For example, the benzene molecule (C6H6) has a delocalized bonding system that results in the stability of the molecule, making it a very important molecule in organic chemistry, known for its aromatic properties. Signup and view all the answers

Study Notes

Chemistry Exam Review - 2018/19

Orbital Filling: The ground state hydrogen atom's electron fills the 1s orbital.
Oxidation: A process where an element loses electrons. Examples: Mg → Mg²⁺ + 2e⁻ or any other reaction that demonstrated oxidation.
Electron Shell Capacity: The maximum number of electrons in the L shell is 8.
Primary Bonds: Ionic bonds, covalent bonds, and metallic bonds are primary bond types. Examples: Ionic bond (NaCl), covalent bonds, metallic bonds.
Brønsted Acids/Bases: Brønsted acids are proton donors (e.g., HCl), and Brønsted bases are proton acceptors (e.g., NH₃).
Lewis Acids/Bases: Lewis acids are electron-pair acceptors, and Lewis bases are electron-pair donors.
pH and Concentration: A solution with pH 1 has 10 times higher H⁺ concentration than a solution with pH 2.
Boiling Point: The temperature at which a liquid turns into a gas, when the vapor pressure equals the external pressure.
Density: Density is the mass of a substance per unit volume (g/dm³). It's an intensive property.
Gibbs Free Energy: A thermodynamic quantity (ΔG = ΔH - TΔS), where ΔG = Gibbs Free Energy, ΔH = enthalpy, T = temperature in Kelvin, ΔS = entropy. Gibbs Free Energy is the energy in a system or process available to do useful work.
Micelles: Aggregates of surfactant molecules in a liquid colloid, with hydrophobic tails grouped in the center and hydrophilic heads facing outwards. Ex. Soap.
Ligands: Molecules or ions attached to a metal atom through coordinate bonding. Ex. NH₃, Cl−, H₂O
Ideal Gas Law: PV = nRT; P = pressure, V = volume, n = moles, R = gas constant, T = temperature
Delocalized Bonds: Electron density spread throughout the molecule, rather than in one fixed position, e.g benzene.
Exothermic/Endothermic Reactions: Exothermic reactions release energy, while endothermic reactions absorb energy.
Isotopes: Atoms with the same atomic number but different mass numbers (e.g. isotopes of Carbon).
Colligative Properties: Properties of solutions that depend on the concentration of solute particles, but not their identity. Examples: vapor pressure lowering, boiling-point elevation, freezing-point depression, osmotic pressure.
Ionization Energy: The amount of energy required to completely remove an electron from a gaseous atom. Higher ionization energy is associated with elements that are further right and higher up in the periodic table.
Galvanic/Electrolysis Cells: Galvanic cells use spontaneous redox reactions to produce electrical energy, while electrolysis uses electrical energy to drive non-spontaneous redox reactions.
Bond Order: Half the difference between the number of bonding and antibonding electrons in a molecule.
Indicators: Substances that change color depending on the pH of a solution, e.g. litmus, phenolphthalein
Colloidal Systems: Mixtures that have particles of one substance dispersed in another, with the dispersed particles remaining suspended. Properties of these systems include the Tyndall effect and how they are classified according to their internal and external phases.
Solubility: The ability of a substance (solute) to dissolve in a solvent.
Buffer System: A solution that resists changes in pH when small amounts of acid or base are added (e.g. Weak acid and its conjugate base, or a weak base and its conjugate acid).
Catalyst: Substances that increase the rate of a chemical reaction without being consumed in the process.
Autocatalysis: A reaction where one of the products acts as a catalyst for the reaction.
Standard Cell Potential: Calculated to find the emf, or electromotive force which can be used to determine the energy related to chemical reactions. Eocell = Eocathode - Eoanode
Hund's Rule: Electrons fill degenerate orbitals singly first before pairing up.
Alkaline Substances: Sodium hydroxide (NaOH), potassium hydroxide (KOH), and calcium hydroxide (Ca(OH)₂).
Detecting Substances: Examples: detection of arsenic ions (Griess-Ilosvay reagent), detection of sulfide ions, and detection of iron(III) ions.
Hydrogen Bonding: A special type of dipole-dipole attraction that occurs between a hydrogen atom bonded to a highly electronegative atom (like O or N) and another electronegative atom.
Hess' Law: The enthalpy change for a reaction is the same regardless of the reaction pathway
Strong and Weak Acids/Bases: Strong acids/bases ionize completely in water, while weak acids/bases ionize partially.
Henry's Law: The solubility of a gas in a liquid is directly proportional to the partial pressure of the gas above the liquid.
Multidentate Ligands: Ligands with more than one donor atom that can coordinate with a central metal ion e.g., to form chelate complexes

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Description

Prepare for your chemistry exam with this comprehensive review covering key concepts including orbital filling, oxidation, and acid-base theories. Explore topics on primary bonds, pH levels, and density to solidify your understanding of the material. Ideal for students studying chemistry in the 2018/19 academic year.