IB CHEMISTRY SEMESTER EXAM - paper 1

Front

What is the atomic number of an element?

Back

The atomic number is the number of protons in the nucleus of an atom, which determines the element's identity.

Front

Define molarity.

Back

Molarity is a measure of concentration, defined as the number of moles of solute per liter of solution (mol/L).

Front

What is the difference between an ionic bond and a covalent bond?

Back

An ionic bond is formed through the transfer of electrons from one atom to another, resulting in charged ions, while a covalent bond is formed by the sharing of electrons between atoms.

Front

Explain the concept of pH.

Back

pH is a measure of the acidity or basicity of a solution, calculated as the negative logarithm of the hydrogen ion concentration.

Front

What is the ideal gas law?

Back

The ideal gas law is a relation between pressure (P), volume (V), temperature (T), and the number of moles (n) of a gas, expressed as PV = nRT.

Front

Define enthalpy change (ΔH).

Back

Enthalpy change is the heat content change of a system at constant pressure, often associated with chemical reactions.

Front

What is a catalyst?

Back

A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process.

Front

Describe the concept of equilibrium in a chemical reaction.

Back

Equilibrium is the state in which the rates of the forward and reverse reactions are equal, resulting in constant concentrations of reactants and products.

Front

What is the significance of the mole concept in chemistry?

Back

The mole concept allows chemists to count particles (atoms, molecules) by weighing them, facilitating stoichiometric calculations.

Front

Explain the term 'oxidation' in redox reactions.

Back

Oxidation is the process of losing electrons or increasing oxidation state during a chemical reaction.