Chemistry Questions et reponses d'entretien
Question 1. What is the purpose of a catalyst in a chemical reaction?
A catalyst speeds up a chemical reaction by providing an alternative reaction pathway with lower activation energy.
Example:
Enzymes act as catalysts in biological systems, facilitating metabolic reactions.
Question 2. Define isotope and provide an example.
Isotopes are atoms of the same element with different numbers of neutrons. Example: Carbon-14 is an isotope of carbon.
Example:
Carbon-14 is used in radiocarbon dating to determine the age of archaeological artifacts.
Question 3. Explain the concept of intermolecular forces.
Intermolecular forces are attractive forces between molecules. They include van der Waals forces, hydrogen bonding, and dipole-dipole interactions.
Example:
Water molecules exhibit hydrogen bonding, leading to higher boiling points compared to similar-sized molecules.
Question 4. What is a redox reaction?
A redox (reduction-oxidation) reaction involves the transfer of electrons between reactants. The substance oxidized loses electrons, while the substance reduced gains electrons.
Example:
The reaction 2H2 + O2 → 2H2O involves the oxidation of hydrogen and reduction of oxygen.
Question 5. Define enthalpy and its relationship with heat in chemical reactions.
Enthalpy is the heat content of a system at constant pressure. In chemical reactions, the change in enthalpy (ΔH) represents the heat exchanged with the surroundings.
Example:
Burning a piece of wood releases heat (exothermic), resulting in a negative ΔH.
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- What is the purpose of a catalyst in a chemical reaction?
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