AQA AS Chemistry June 2024 Paper 1 Video Walkthrough

Introduction

• Purpose: Walkthrough of the AQA AS Chemistry June 2024 Paper 1.
• Encouragement to like, subscribe, and comment with questions.

Question 1: Reactions with Potassium Halides

• Experiment Setup:
  • Student adds bromine water to potassium halide solutions (chloride, bromide, iodide).
  • Bromine water added to water acts as a control.
• Observations:
  • Solutions P and R show no change (remain orange).
  • Solution Q turns brown, indicating the presence of iodine.
• Ionic Equation:
  • Iodide ion reacts with bromine to form bromide ions and iodine.
• Oxidizing Ability:
  • Bromine is not strong enough to oxidize chlorine or itself.

Experiment 2: Identifying Halide Ions

• Silver Nitrate Test:
  • Silver chloride (white precipitate), silver bromide (cream precipitate), silver iodide (yellow precipitate).
• Ammonia Test:
  • Dilute ammonia dissolves silver chloride but not silver bromide.

Question 2: Group 2 Elements

• Ionization Energy of Beryllium:
  • Third ionization requires more energy as electron is closer to the nucleus in lower energy shell (1s vs 2s).
• Reaction of Magnesium:
  • With cold water: Produces magnesium oxide and hydrogen gas.
  • With steam: Produces magnesium hydroxide and hydrogen gas.
• Calcium with Water:
  • Redox reaction: Calcium oxidized, hydrogen reduced.

Question 3: Structure and Bonding

• Electronegativity:
  • Ability of an atom to attract electrons in a covalent bond.
• Polarity of C-Cl Bond:
  • Chlorine is more electronegative than carbon, causing a dipole.
• Non-Polarity of CCl₄:
  • Tetrahedral symmetry cancels dipoles.
• Van der Waals Forces:
  • Caused by temporary dipoles due to electron cloud movement.

Question 4: Identifying Solutions

• Tests to identify ammonium nitrate, potassium sulfate, sodium carbonate, and magnesium nitrate.
• Silver Nitrate & Ammonia Tests for halides.
• Reactions:
  • Sodium carbonate with acid forms CO₂ (tested with limewater).

Question 5: Shapes and Bond Angles

• SF₆: Octahedral, 90° angles.
• SF₃⁺: Trigonal pyramidal, 107° angles due to lone pair repulsion.

Question 6: Atomic Structure and Mass Spectrometry

• Electron Configuration of Bromine: Ends in 4p⁵.
• Mass Spectrometry:
  • Bromine isotopes 79 and 81.
  • Equal abundances lead to characteristic mass spectrum peaks.

Question 7: Magnesium Oxide Experiment

• Percentage Uncertainty Calculation using balance readings.
• Moles Calculation of HCl and subsequent reactions in titration.
• Percentage by Mass Calculation of MgO in tablets.

Question 8: Silver Nitrate and Thermochemistry

• Standard Enthalpy of Formation: Formation from elements in standard states.
• Enthalpy Calculations using Hess' Law.
• Experimental Challenges with thermal decomposition.

Section B: Multiple Choice Questions

• Questions cover topics like atom economy, dative covalent bonds, titration accuracy, and electron configurations.
• Explanations provided for each choice.

Conclusion

• Encouragement to use the walkthrough as a study aid.
• Reminder to like and subscribe for more content.