AP Chemistry Laboratory Skills Review

Introduction

• Presenter: Jeremy Krug
• Purpose: Review main lab skills needed for AP Chemistry Exam
• Note: This review complements a full lab program and offers key insights for the exam
• Resources: Further course materials available at UltimateReviewPacket.com

Laboratory Safety

• Safety Precautions:
  • Always wear safety goggles
  • Never touch chemicals with bare fingers
  • Add concentrated acid to water, not the other way around
  • Neutralize acid spills with a weak base (e.g., baking soda)
  • Neutralize base spills with a weak acid (e.g., vinegar)
  • Avoid using strong acids/bases for neutralization due to risk of strong residuals

Colors of Ionic Solutions

• Copper Ions: Blue
• Iron Ions: Yellow or Orange
• Nickel Ions: Green
• Cobalt Ions: Pink
• Chromium Ions: Yellowish or Orange

Lab Equipment and Their Uses

• Pipette:
  • Used to dispense specific volumes (common sizes: 10 mL and 25 mL)
• Buret:
  • Used to measure dispensed liquid volume, especially in titrations
  • Zero mark at the top; read one decimal place between lines
  • Read meniscus at the vertex
• Graduated Cylinder:
  • Used for somewhat precise measurements
• Beaker:
  • Not for precise measurements; used to contain liquids
• Flasks:
  • Florence Flask: Storage for solutions, no measurement marks
  • Erlenmeyer Flask: Narrow neck, used to swirl solutions
  • Volumetric Flask: Used for precise solution concentration preparation

Key Chemistry Experiments

• Acid-Base Titrations:
  • Equation: Molarity (acid) x Volume (acid) = Molarity (base) x Volume (base)
  • Involves using a pipette, indicator, and buret
  • Endpoint indicated by color change
  • pKa equals pH at the titration curve halfway to equivalence point

Separation Techniques

• Filtration:
  • Separates solids from liquids
• Distillation:
  • Separates liquids with different boiling points
• Chromatography:
  • Separates solution components based on intermolecular forces
  • Types: Column and Paper Chromatography

Spectrophotometry

• Select wavelength with highest absorbance
• Use known concentrations to create a calibration curve
• Estimate unknown concentrations by measuring absorbance

Error Analysis

• Experiment Errors:
  • Use algebra to understand effects (e.g., Beer-Lambert Law: A = εbc)
  • Example: Water contamination lowers concentration and absorbance
• Ideal Gas Law Errors:
  • Example: Incorrect thermometer leads to wrong mole calculation
• Percent Error Calculation:
  • Percent Error = |(Calculated - Correct) / Correct| x 100

Conclusion

• Encouragement to engage with additional resources and videos

Call to Action

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