Chemistry HL
6
Chapters
243
Notes
Chapter 1 - Models Of The Particulate Nature Of Matter
Chapter 2 - Models Of Bonding & Structure
Chapter 3 - Classification Of Matter
Chapter 4 - What Drives Chemical Reactions?
Chapter 5 - How Much, How Fast & How Far?
Chapter 6 - What Are The Mechanisms Of Chemical Change?
Chemistry HL
Chapter 6 - What Are The Mechanisms Of Chemical Change?
Unlocking Battery Science: Primary Vs. Secondary Cells Explained
550 words
3 mins read
Last edited on 5th Nov 2024
Table of content
Electrochemical Cells 101 🔋
-
Battery: Combination of two or more electrochemical cells, housed together.
- 💡 Think of a battery as a party where cells come together to provide energy.
-
Primary Electrochemical Cell
- Can't be recharged.
- When it's done, it's done (like a one-time party! 🎉).
- Anode (negative side) gets oxidized; hence, unusable after a point.
- Problem: Polarization; Can stop the reaction (imagine party guests getting stuck at the door 🚪).
- Not good for high-demand activities like car racing. More suited for low-key stuff like household devices.
-
Secondary Electrochemical Cell
- The "come-back" cell – it can be recharged 🔄.
- Handles higher energy demands (like big concerts 🎶).
- But! It self-discharges faster. This means if you buy a new phone battery, charge it first; it lost some juice on the journey to you.
Case Study: Car Batteries - Lead-Acid Battery 🚗
- Main Job: Start the engine and power up car systems.
- When the car works, the battery drains; when the car rests, the battery recharges.
- Components
- Anode: Lead (Pb)
- Cathode: Lead(IV) oxide (PbO2)
- Electrolyte: Sulfuric Acid (H2SO4)
- Reactions
- Discharge
- Anode: Pb + HSO4⁻ → PbSO4 + H+ + 2e⁻
- Cathode: PbO2 + 3H+ + HSO4⁻ + 2e⁻ → PbSO4 + 2H2O
- Overall: Pb + PbO2 + 2H2SO4 → 2PbSO4 + 2H2O
- Charging
- Basically the reverse!
- Continual charging can make hydrogen and oxygen from water, so car batteries occasionally need a refill with distilled water.
Case Study: Lithium-ion Batteries 🔌
- Not just pure lithium, they have lithium atoms in graphite.
- Anode: Lithium in graphite
- Cathode: Lithium-cobalt oxide (LiCoO2)
- Medium: Non-aqueous polymer gel (because lithium + water = 💥).
- Discharge: Li (from anode) + CoO2 (from cathode) → LiCoO2
- Charging: Reverse of discharge. Lithium ions travel back to anode and embed themselves in graphite.
Unlock the Full Content! 
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Chemistry HL
Chapter 6 - What Are The Mechanisms Of Chemical Change?
Unlocking Battery Science: Primary Vs. Secondary Cells Explained
550 words
3 mins read
Last edited on 5th Nov 2024
Table of content
Electrochemical Cells 101 🔋
-
Battery: Combination of two or more electrochemical cells, housed together.
- 💡 Think of a battery as a party where cells come together to provide energy.
-
Primary Electrochemical Cell
- Can't be recharged.
- When it's done, it's done (like a one-time party! 🎉).
- Anode (negative side) gets oxidized; hence, unusable after a point.
- Problem: Polarization; Can stop the reaction (imagine party guests getting stuck at the door 🚪).
- Not good for high-demand activities like car racing. More suited for low-key stuff like household devices.
-
Secondary Electrochemical Cell
- The "come-back" cell – it can be recharged 🔄.
- Handles higher energy demands (like big concerts 🎶).
- But! It self-discharges faster. This means if you buy a new phone battery, charge it first; it lost some juice on the journey to you.
Case Study: Car Batteries - Lead-Acid Battery 🚗
- Main Job: Start the engine and power up car systems.
- When the car works, the battery drains; when the car rests, the battery recharges.
- Components
- Anode: Lead (Pb)
- Cathode: Lead(IV) oxide (PbO2)
- Electrolyte: Sulfuric Acid (H2SO4)
- Reactions
- Discharge
- Anode: Pb + HSO4⁻ → PbSO4 + H+ + 2e⁻
- Cathode: PbO2 + 3H+ + HSO4⁻ + 2e⁻ → PbSO4 + 2H2O
- Overall: Pb + PbO2 + 2H2SO4 → 2PbSO4 + 2H2O
- Charging
- Basically the reverse!
- Continual charging can make hydrogen and oxygen from water, so car batteries occasionally need a refill with distilled water.
Case Study: Lithium-ion Batteries 🔌
- Not just pure lithium, they have lithium atoms in graphite.
- Anode: Lithium in graphite
- Cathode: Lithium-cobalt oxide (LiCoO2)
- Medium: Non-aqueous polymer gel (because lithium + water = 💥).
- Discharge: Li (from anode) + CoO2 (from cathode) → LiCoO2
- Charging: Reverse of discharge. Lithium ions travel back to anode and embed themselves in graphite.
Unlock the Full Content!
Dive deeper and gain exclusive access to premium files of Chemistry HL. Subscribe now and get closer to that 45 🌟
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