Chemistry Rate of Change Quiz

Rate of Change

• Rate of reaction is the speed at which reactants are converted into products.
• Measured by the change in concentration of a reactant or product per unit time.
• Factors affecting rate:
  • Temperature: Higher temperatures increase kinetic energy of particles, leading to more frequent and energetic collisions, thus faster reactions.
  • Concentration: Higher concentration increases the number of reactant particles per unit volume, increasing collision frequency and reaction rate.
  • Surface area: Larger surface area increases the area of contact between reactants, leading to more frequent collisions and faster reaction rate.
  • Catalysts: A catalyst speeds up a reaction without being consumed. It provides an alternative reaction pathway with a lower activation energy.
• Rate equations express the relationship between reaction rate and reactant concentration. The overall order of the reaction is determined by the sum of the orders of individual reactants.
• Different types of reactions have different rate laws.

Chemistry of the Atmosphere

• The atmosphere is a mixture of gases, primarily nitrogen (N₂), oxygen (O₂), and argon (Ar).
• Important atmospheric gases include:
  • Carbon dioxide (CO₂): Plays a crucial role in the greenhouse effect.
  • Water vapor (H₂O): Essential for weather patterns and contributes to the greenhouse effect.
  • Ozone (O₃): Absorbs harmful UV radiation in the stratosphere, but is a pollutant in the troposphere.
• Atmospheric pollution: Sources include:
  • Burning fossil fuels: Releases pollutants like sulfur dioxide (SO₂), nitrogen oxides (NO_x).
  • Industrial processes: Release various pollutants.
  • Vehicle emissions: Release pollutants like carbon monoxide (CO), nitrogen oxides (NO_x), and unburnt hydrocarbons.
• Atmospheric chemistry studies the chemical processes occurring in the atmosphere:
  • Photochemical reactions: Reactions initiated by light absorption, like smog formation.
  • Acid rain: Formation caused by the reaction of sulfur oxides and nitrogen oxides with water in the atmosphere.
  • Greenhouse effect: The absorption of infrared radiation by greenhouse gases, leading to global warming.

Chemical Analysis

• Techniques for determining the identity and quantity of substances in a sample.
• Qualitative analysis: Identifies the components present in a sample.
• Quantitative analysis: Determines the amount of each component in a sample.
• Common techniques:
  • Titration: A technique used to determine the concentration of an unknown solution by reacting it with a solution of known concentration.
  • Spectroscopy: Use of electromagnetic radiation to identify and quantify components of a sample. Different types of spectroscopy include UV-Vis, IR, and NMR spectroscopy.
  • Chromatography: Separates components of a mixture based on their different properties. Common types include gas chromatography (GC) and high-performance liquid chromatography (HPLC).
  • Colorimetry: Measures absorbance of light by a solution to determine the concentration of a colored substance.
  • Atomic absorption spectroscopy (AAS): Measures the absorption of light by atoms in a sample (especially metals).
• Common errors in chemical analysis
• Steps to minimizing error
• Importance of safety in chemical analysis techniques
• Precautions while using chemical reagents.