Unit 1

main points

What is the mole concept in chemistry?

The mole is a unit that measures the amount of substance. It is defined as exactly 6.022 x 10^23 particles (atoms, molecules, etc.).

Explain Avogadro's Law.

Avogadro's Law states that equal volumes of gases at the same temperature and pressure contain an equal number of molecules. 6.02•10²³

What is the significance of the atomic mass unit (amu)?

The atomic mass unit is a standard unit for indicating mass on an atomic or molecular scale, defined as one twelfth of the mass of a carbon-12 atom.

What is a limiting reactant?

The limiting reactant is the substance that is totally consumed when the chemical reaction occurs; it determines the amount of product formed.

Identify the three types of chemical bonds.

The three main types of chemical bonds are ionic, covalent, and metallic bonds.

What does the term 'stoichiometry' refer to?

Stoichiometry refers to the calculation of reactants and products in chemical reactions using balanced equations.

Define mass percent composition.

Mass percent composition is the mass of an element in a compound divided by the total mass of the compound, multiplied by 100.

What is the difference between an empirical formula and a molecular formula?

An empirical formula shows the simplest whole-number ratio of elements in a compound, while the molecular formula shows the actual number of atoms of each element.

How do you calculate the molarity of a solution?

Molarity (M) is calculated by dividing the number of moles of solute by the volume of solution in liters.

What is a dilute solution?

A dilute solution contains a small amount of solute relative to the solvent.

What is the difference between an element and a compound?

An element is a pure substance that consists of only one type of atom, while a compound is a substance formed when two or more different types of atoms bond together.

What is the Law of Conservation of Mass?

The Law of Conservation of Mass states that mass is neither created nor destroyed in a chemical reaction; the total mass of reactants equals the total mass of products.

Define the term 'solution'.

A solution is a homogeneous mixture of two or more substances, consisting of a solute (the substance being dissolved) and a solvent (the substance doing the dissolving).

What is a solute?

A solute is the substance that is dissolved in a solvent to form a solution.

What is a solvent?

A solvent is the substance that dissolves a solute to form a solution. Water is often referred to as the universal solvent.

Explain what an acid and a base are in terms of pH.

Acids have a pH less than 7, indicating a higher concentration of hydrogen ions (H+), while bases have a pH greater than 7, indicating a lower concentration of hydrogen ions.

What is a reduction-oxidation (redox) reaction?

A redox reaction is a chemical reaction that involves the transfer of electrons between two species, changing their oxidation states.

What are intermolecular forces?

Intermolecular forces are forces of attraction or repulsion that act between neighboring particles (atoms, molecules, or ions), significantly affecting the physical properties of substances.

What is the ideal gas law?

The ideal gas law describes the relationship between pressure (P), volume (V), temperature (T), and the number of moles (n) of an ideal gas: PV = nRT, where R is the ideal gas constant.

What is the purpose of a balanced chemical equation?

A balanced chemical equation ensures that the number of atoms of each element is conserved in a reaction, reflecting the Law of Conservation of Mass.

What are the different types of intermolecular forces and their effects?

The main types of intermolecular forces are: 1. **London Dispersion Forces**: Weak forces due to temporary shifts in electron density; present in all molecules, more significant in larger atoms. 2. **Dipole-Dipole Interactions**: Occur between polar molecules; stronger than dispersion forces, affecting boiling/melting points. 3. **Hydrogen Bonds**: A strong type of dipole-dipole interaction occurring between molecules with H bonded to N, O, or F; significantly increases boiling points. These forces influence physical properties like boiling/melting points, viscosity, and solubility.