Which one among the following is an example of chemical change?

The correct answer is Mixing of NaOH and HCl.

Key Points

• Mixing of NaOH (sodium hydroxide) and HCl (hydrochloric acid) results in a chemical reaction.
• This reaction is an example of a neutralization reaction, where an acid reacts with a base to produce a salt and water.
• The balanced chemical equation for this reaction is: NaOH + HCl → NaCl + H₂O.
• In this process, new substances (sodium chloride and water) are formed, indicating a chemical change.
• Energy is usually released in the form of heat during this exothermic reaction.

Additional Information

• Chemical Change
  • A chemical change results in the formation of one or more new substances with different properties.
  • Indicators of a chemical change include color change, temperature change, gas production, and the formation of a precipitate.
  • Examples include rusting of iron, burning of wood, and baking a cake.
• Neutralization Reaction
  • A neutralization reaction occurs when an acid and a base react to form water and a salt.
  • These reactions are typically exothermic, releasing heat.
  • Neutralization reactions are important in various industrial processes, laboratory experiments, and even in everyday life, such as in antacid tablets neutralizing stomach acid.
• Exothermic Reaction
  • An exothermic reaction is a chemical reaction that releases energy through light or heat.
  • Common examples include combustion reactions and many oxidation reactions.
  • Exothermic reactions are characterized by an increase in the temperature of the surroundings.
• Balanced Chemical Equation
  • A balanced chemical equation has the same number of each type of atom on both sides of the equation.
  • Balancing equations is essential to follow the Law of Conservation of Mass, which states that mass is neither created nor destroyed in a chemical reaction.
  • Balancing equations ensures that the chemical process is accurately represented.