Definitions MCQ

Questions and Answers

What is the significance of Avogadro’s Law in the context of gases?

It applies only to gases at varying temperatures and pressures.

It states that equal volumes of gases contain different numbers of molecules.

It describes the behavior of liquids at standard temperature and pressure.

It indicates that equal volumes of gases under the same conditions contain the same number of molecules. (correct)

Which statement correctly defines an Arrhenius acid?

A substance that reacts with hydroxide ions to form water.

A substance that dissociates to produce hydrogen ions in an aqueous solution. (correct)

A water-soluble substance that is available in pure form.

A substance that donates protons in an aqueous solution.

What distinguishes a Bronsted-Lowry acid from an Arrhenius acid?

Bronsted-Lowry acids cannot exist in aqueous solution.

Bronsted-Lowry acids are always solid, while Arrhenius acids are aqueous.

Bronsted-Lowry acids are defined as proton donors, while Arrhenius acids produce hydrogen ions. (correct)

Both definitions overlap completely and are interchangeable.

Which term describes a species that differs by a proton?

Conjugate acid-base pair Signup and view all the answers

What is meant by activation energy in a chemical reaction?

The minimum energy that reacting particles must have to initiate a reaction. Signup and view all the answers

What characterizes autocatalysis in a chemical reaction?

The product acts as a catalyst for the same reaction. Signup and view all the answers

Which of the following best describes heterogeneous catalysis?

The catalyst is in a different physical phase than the reactants. Signup and view all the answers

What does the rate of reaction measure?

The change in concentration of any reactant or product over time. Signup and view all the answers

How is half-life defined in the context of isotopes?

The time taken for half the atoms in a sample to decay. Signup and view all the answers

What is a radioisotope?

An isotope that emits radiation due to its instability. Signup and view all the answers

What defines a reducing agent in a chemical reaction?

A substance that loses electrons and causes reduction Signup and view all the answers

Which statement accurately describes electrolysis?

It requires a conductive solution to break down a substance Signup and view all the answers

Which of the following correctly defines oxidation in terms of oxidation number?

An increase in oxidation number Signup and view all the answers

In the context of Boyle’s Law, how is the volume of a gas related to its pressure?

Inversely proportional at constant temperature Signup and view all the answers

What distinguishes primary alcohol from secondary alcohol?

Number of adjacent carbon atoms to the carbon with the OH group Signup and view all the answers

What does Gay-Lussac’s Law describe about gaseous reactions?

The volumes of reacting gases and gaseous products relate by whole number ratios Signup and view all the answers

Which of the following statements is true about structural isomers?

They have different arrangements of the same molecular formula. Signup and view all the answers

What happens in an endothermic reaction?

Heat is absorbed during the reaction Signup and view all the answers

How is bond energy defined?

Energy required to break one mole of bonds in gaseous state Signup and view all the answers

What principle does Hess's Law illustrate regarding chemical reactions?

Enthalpy changes are independent of the pathway of the reaction Signup and view all the answers

What does the octane number measure?

The tendency of a fuel to resist auto-ignition Signup and view all the answers

What happens according to Le Chatelier’s Principle when a system at equilibrium is stressed?

The system adjusts to minimize the effect of the stress Signup and view all the answers

Which of the following correctly defines pH?

The negative logarithm of the concentration of hydrogen ions Signup and view all the answers

What characterizes hard water?

Water that does not easily form a lather with soap Signup and view all the answers

Which type of hardness in water can be removed by boiling?

Temporary Hardness Signup and view all the answers

What is the relationship defined by the dissociation constant of water?

Kᵥᵥ = [H₃O⁺] x [OH⁻] Signup and view all the answers

What defines biochemical oxygen demand (BOD)?

The amount of dissolved oxygen consumed by biological action Signup and view all the answers

What outcome occurs when small suspended solids in water undergo flocculation?

Solids come together to form larger aggregates Signup and view all the answers

What is true about reversible reactions?

They can take place in either direction Signup and view all the answers

What is the term for the sum of protons and neutrons in an atom's nucleus?

Mass Number Signup and view all the answers

Which statement correctly describes electronegativity?

It is the relative attraction of an atom for shared electrons. Signup and view all the answers

What does the first ionization energy refer to?

Energy required to remove a loosely bound electron from gaseous atoms. Signup and view all the answers

Which interaction is defined as the attractive forces between permanent dipoles on two polar molecules?

Dipole-dipole Interactions Signup and view all the answers

What principle states that it is impossible to know both the exact position and the exact velocity of an electron simultaneously?

Heisenberg’s Uncertainty Principle Signup and view all the answers

Which bond is formed by the sharing of a pair of electrons between non-metal atoms?

Covalent Bond Signup and view all the answers

What is the correct definition of oxidation?

The loss of electrons during a reaction. Signup and view all the answers

What is the role of an oxidizing agent in a chemical reaction?

It allows oxidation to occur by gaining electrons. Signup and view all the answers

Which of the following best describes an energy sub-level?

A grouping of atomic orbitals with the same energy. Signup and view all the answers

How is the atomic radius of an element defined?

Half the distance between the nuclei of two bonded atoms. Signup and view all the answers

Study Notes

Avogadro’s Law

Equal volumes of gases at the same temperature and pressure contain the same number of molecules.

Mole Concept

A mole represents the amount of substance that contains as many particles (atoms, molecules, or ions) as there are atoms in 12 grams of carbon-12 (¹²C).

Arrhenius Acids and Bases

Arrhenius Acid: Dissociates in water to produce hydrogen ions (H⁺).
Arrhenius Base: Dissociates in water to produce hydroxide ions (OH⁻).

Bronsted-Lowry Theory

Bronsted-Lowry Acid: Defined as a proton donor, capable of donating hydrogen ions.
Bronsted-Lowry Base: Defined as a proton acceptor, capable of accepting hydrogen ions.

Conjugate Acid-Base Pairs

Consist of two species that differ by the presence or absence of a single proton.

Primary Standard

A stable, pure, water-soluble substance used in titrations to create a standard solution.

Standard Solution

A solution with a concentration that is precisely known, used for quantitative chemical analyses.

Activation Energy

The minimum energy that colliding particles must possess for a chemical reaction to occur.

Autocatalysis

Autocatalysis occurs when the product of a chemical reaction acts as a catalyst for that same reaction.

Catalyst

A catalyst is a substance that changes the reaction rate without undergoing any permanent change itself during the process.

Effective Collision

Effective collisions in chemical reactions require sufficient activation energy to result in the formation of products.

Heterogeneous Catalysis

Heterogeneous catalysis involves a catalyst that exists in a different physical state or phase than the reactants involved in the reaction.

Rate of Reaction

The rate of reaction measures the change in concentration of a reactant or product over a specified unit of time.

Half Life

Half-life is defined as the duration it takes for half of the atoms in a radioactive sample to decay.

Isotopes

Isotopes are variants of elements that have the same atomic number but differ in mass number due to varying numbers of neutrons.

Radioactivity

Radioactivity refers to the spontaneous disintegration of unstable atomic nuclei, resulting in the emission of radiation.

Radioisotope

A radioisotope is a specific type of isotope that exhibits radioactivity.

Atomic Number

The atomic number indicates the number of protons present in the nucleus of an atom, defining the element's identity.

Atomic Structure and Bonds

Mass Number: Sum of protons and neutrons in an atom’s nucleus.
Relative Atomic Mass (Aᵣ): Average atom mass relative to 1/12 the mass of Carbon-12.
Atomic Orbital: Region with a probability (>95%) of finding an electron around the nucleus.
Energy Level: Defined energy region electrons can occupy within an atom.
Energy Sub-Level: Comprised of a group of atomic orbitals of the same energy.
Heisenberg’s Uncertainty Principle: One cannot simultaneously know an electron's exact position and velocity.
Covalent Bond: Formed by sharing a pair of electrons between two non-metal atoms.
Ionic Bond: Electrostatic attraction between oppositely charged ions.
Electronegativity: Indicates an atom's relative attraction for shared electrons in a covalent bond.

Ionization Energy

1ˢᵗ Ionization Energy: Minimum energy required to remove the most loosely bound electron from 1 mole of gaseous atoms.
2ⁿᵈ Ionization Energy: Energy needed to remove the most loosely bound electron from each singly charged positive ion in a mole.

Molecular Structure

Atomic Radius: Half the distance between nuclei of two atoms linked by a single covalent bond.
Dipole-dipole Interactions: Forces between permanent dipoles of polar molecules.
Hydrogen Bonding: Strong dipole-dipole interaction when hydrogen bonds with O, N, or F.
Van der Waals Forces: Weak attractions resulting from temporary dipoles between molecules.

Redox Reactions

Oxidation: Loss of electrons (Remember OIL - Oxidation Is Loss).
Oxidizing Agent: Substance that undergoes reduction by gaining electrons.
Reducing Agent: Substance that undergoes oxidation by losing electrons.
Reduction: Gain of electrons in a reaction (Remember RIG - Reduction Is Gain).

Electrochemistry

Active Electrodes: React with the electrolyte.
Electrode: Conductor linked to battery ends.
Electrolysis: Decomposing substances using electric current in solution or molten form.
Electrolyte: Conducts electricity when dissolved or molten.
Electroplating: Coating a less expensive metal with a more expensive one.
Inert Electrodes: Do not react with the electrolyte.
Electrochemical Series: Metals arranged by their tendency to lose electrons.

Gas Laws

Boyle’s Law: At constant temperature, gas volume inversely relates to pressure.
Charles’ Law: At constant pressure, gas volume directly relates to Kelvin temperature.
Diffusion: Spontaneous substance spreading due to particle movement.
Gay-Lussac’s Law: Gaseous volumes react in simple whole number ratios under identical conditions.

Thermodynamics

Ideal Gas: Follows all kinetic theory assumptions under various conditions.
Volatile Liquid: Easily evaporates with a low boiling point.
Empirical Formula: Shows the simplest whole number ratio of elements in a compound.
Molecular Formula: Specifies the actual number of each type of atom in a molecule.
Structural Formula: Describes the arrangement of atoms in a molecule.
Structural Isomers: Compounds with the same molecular formula but different structures.

Organic Chemistry

Chloro-alkanes: Alkanes with at least one replaced hydrogen by chlorine.
Homologous Series: Family of compounds with the same general formula and differing by CH₂.
Hydrocarbons: Compounds of hydrogen and carbon with covalent bonds.
Primary Alcohol: OH group carbon is attached to one other carbon.
Secondary Alcohol: OH carbon attached to two other carbons.
Tertiary Alcohol: OH carbon attached to three other carbons.
Auto-ignition: Occurs when ignition happens before a spark.

Chemical Energetics

Bond Energy: Energy needed to break one mole of specific bonds in gaseous state.
Endothermic Reaction: Heat absorbed during a reaction.
Exothermic Reaction: Heat released during a reaction.
Heat of Combustion: Kilojoules released when one mole of a substance is burned in excess oxygen.
Heat of Formation: Kilojoules change when forming one mole of a substance from its elements.
Heat of Reaction (∆H): Heat released or absorbed based on reactant mole quantity in a balanced equation.
Hess’s Law: Heat change is dictated only by initial and final states, regardless of path.
Law of Conservation of Energy: Energy changes form but is not created or destroyed.

Chemical Equilibrium

Octane Number: Measure of a fuel's resistance to auto-ignition.
Hydrolysis: Chemical breakdown of a substance by water with decomposition.
Chemical Equilibrium: State where forward and reverse reaction rates are equal.
Le Chatelier’s Principle: A system at equilibrium adjusts to minimize stress effects.
Reversible Reaction: Reactions capable of proceeding in either direction.

Water Chemistry

Dissociation Constant of Water: Kᵥᵥ = [H₃O⁺] x [OH⁻] = 1 x 10⁻¹⁴
pH of a Solution: pH = -log₁₀[H₃O⁺], representing hydrogen ion concentration.
Flocculation: Aggregation of small suspended solids in water.
Hard Water: Does not readily form lather with soap.
Permanent Hardness: Cannot be removed by boiling.
Soft Water: Easily forms lather with soap.
Temporary Hardness: Can be removed by boiling.
Biochemical Oxygen Demand (BOD): Amount of dissolved oxygen in ppm consumed by biological processes over 5 days at 20°C in darkness.

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Test your knowledge on Avogadro's Law, the definition of moles, and the concepts of Arrhenius and Bronsted-Lowry acids and bases. This quiz will enhance your understanding of fundamental chemistry principles related to gases and acids. Perfect for students looking to solidify their grasp on these essential topics.