Chem chap 3

• What are the two types of changes discussed in the study material?

  Physical changes and chemical changes
• What happens to molecules during a physical change?

  Only the arrangement of molecules changes
• What is the balanced chemical equation for the reaction between magnesium and hydrochloric acid?

  Mg + 2HCl → MgCl₂ + H₂ + heat
• What is electroplating?

  A process that uses electricity to coat one metal with another
• What is the purpose of using electricity in electroplating?

  To obtain a thin coating of a particular metal on other metallic objects
• What are endoergic and exoergic reactions?

  • Endoergic reactions: Absorb energy
  • Exoergic reactions: Liberate energy
• What types of cells are mentioned in the study material?

  • Dry cell
  • Mercury cell
  • Nickel-cadmium cell
  • Lithium ion cell
• What are some uses of the different types of cells mentioned?

  They are used in radios, cameras, toys, and mobile phones
• What is the function of a dry cell?

  It is used in portable electronic devices like radios and torches
• What is the function of a lithium ion cell?

  It is used in mobile phones and laptops
• What is the role of acids in fruit cells?

  They react with metals to produce electricity
• How do chemical reactions relate to energy changes?

  They involve the absorption or liberation of energy
• What types of energy changes are involved in the chemical reactions discussed?

  • Heat energy
  • Light energy
  • Electrical energy
• What are cells used for in terms of energy?

  Cells are widely used sources of electrical energy.
• How is electricity produced in cells?

  Electricity is produced in cells through chemical reactions.
• What are some common types of cells and their uses?

  • Dry cell: Radios, torches
  • Mercury cell: Cameras, clocks
  • Nickel-cadmium cell: Rechargeable torches, cameras
  • Lithium ion cell: Mobile phones, laptops
• What is the chemical formula for sodium?

  The chemical formula for sodium is Na.
• What happens to cells after their use?

  Cells need to be disposed of properly after their use.
• Which types of cells can be recharged?

  Nickel-cadmium cells and lithium ion cells can be recharged.
• What is the purpose of the silver rod and iron ring in the electroplating process?

  The silver rod and iron ring are used to coat the iron ring with a thin layer of silver metal.
• What solution is used to coat copper in the electroplating process?

  Copper sulfate solution is used to coat copper.
• What are endoergic and exoergic reactions?

  • Endoergic reactions: Absorb energy
  • Exoergic reactions: Liberate energy
• What is an example of a chemical reaction that liberates heat energy?

  The reaction between magnesium and hydrochloric acid liberates heat energy.
• What type of reaction is the neutralization reaction between sodium hydroxide and hydrochloric acid?

  The neutralization reaction is an exothermic reaction that liberates heat.
• What are the differences between physical and chemical changes?

  • Physical change: Only a change in the arrangement of molecules occurs.
  • Chemical change: New molecules are formed.
• What happens when you connect a copper rod and a zinc strip to an LED using a conducting wire?

  The LED glows due to the reaction of acids in the lemon with the metals.
• What are electrochemical reactions?

  • Reactions in which electrical energy is consumed or produced.
• What is electroplating?

  Electroplating is the process of obtaining a thin coating of a particular metal on other metallic objects using electricity.