Chemistry Notes – Grade 10
National Curriculum Pakistan - NCP
Chapter 4: Electrochemistry
Aligned with National Curriculum Pakistan (Federal Board, NBF, PTB)
- What are electrochemical cells?
Electrochemical cells are devices that convert chemical energy into electrical energy or electrical energy into chemical energy. - Name the two types of electrochemical cells.
Electrolytic cells and galvanic (voltaic) cells. - What is an electrolytic cell?
An electrochemical cell in which electrical energy is supplied from an external source to drive a non-spontaneous chemical reaction. - What is a galvanic cell?
A cell that generates electrical energy from a spontaneous redox reaction. - What are electrochemical processes based on?
They are based on oxidation-reduction (redox) reactions involving the transfer of electrons. - What is a spontaneous reaction?
A reaction that occurs naturally without external energy input, often releasing energy. - What is a non-spontaneous reaction?
A reaction that requires continuous energy input to proceed. - Define an electrolyte.
An electrolyte is a substance that conducts electricity when dissolved in water or molten, due to the presence of free-moving ions. - Give examples of electrolytes.
Sodium chloride (NaCl), potassium chloride (KCl), hydrochloric acid (HCl), and sodium hydroxide (NaOH). - Define a non-electrolyte.
A non-electrolyte is a substance that does not conduct electricity in molten or aqueous state because it doesn’t form ions. - Give examples of non-electrolytes.
Urea, glucose, sucrose, and benzene. - What does an electrolytic cell consist of?
A vessel with electrolyte solution, two inert electrodes (anode and cathode), and an external power source (battery). - What happens at the anode in an electrolytic cell?
Oxidation occurs—anions lose electrons. - What happens at the cathode in an electrolytic cell?
Reduction occurs—cations gain electrons. - Write the general half-reaction at the anode.
X⁻ → X + e⁻ (oxidation) - Write the general half-reaction at the cathode.
M⁺ + e⁻ → M (reduction) - What is Down’s Cell used for?
To extract sodium metal and chlorine gas by electrolysis of molten sodium chloride on an industrial scale. - What are the electrodes in Down’s Cell?
Iron is used as the cathode and carbon (graphite) as the anode. - Write the anode reaction in Down’s Cell.
2Cl⁻ → Cl₂(g) + 2e⁻ (oxidation)
Tags
electrochemical cells
electrolyte examples
electrolytic cell
galvanic cell
non-electrolyte examples
non-spontaneous reaction
redox reaction
spontaneous reaction