Question 1: Define a catalyst and explain its role in chemical reactions.

Answer: A catalyst is a substance that speeds up a chemical reaction without being consumed in the process. It provides an alternative reaction pathway with lower activation energy.

Question 2: Describe how catalysts are used in forensic science to assist investigations.

Answer: In forensic science, catalysts can speed up reactions used to detect or analyze substances, such as speeding up the breakdown of chemicals in samples to identify substances or enhance detection methods.

Question 3: Explain the mechanism by which a catalyst increases the rate of a reaction.

Answer: A catalyst increases reaction rate by providing an alternative pathway with a lower activation energy, making it easier for reactant molecules to convert into products.

Question 1: The activation energy for a reaction without a catalyst is 80 kJ/mol. When a catalyst is added, the activation energy drops to 40 kJ/mol. Using the Arrhenius equation, estimate how much faster the reaction occurs at 298 K with the catalyst compared to without it. (Use: Rate ∝ e^(-Ea/RT), R=8.314 J/mol·K).

Answer: Reaction rate ratio = e^(-Ea_without / RT) / e^(-Ea_with / RT) = e^{(Ea_with - Ea_without)/RT} = e^{(40000 - 80000)/(8.314*298)} ≈ e^{(-40000)/(2477.572)} ≈ e^{-16.13} ≈ 1.07 x 10^(-7). Note: Since the exponential of a large negative number is very small, the reaction with the catalyst is significantly faster, roughly 23 million times faster than without the catalyst.

Question 1: Describe a basic experimental setup to test whether a substance acts as a catalyst in breaking down a specific chemical found at a crime scene.

Answer: Set up two reaction vessels containing the same reactant solution. Add the suspected catalyst to one vessel while leaving the other as a control. Measure the time taken for the reactant to fully react or produce a detectable product, ensuring safety precautions such as wearing gloves and goggles are followed. Compare the reaction times to determine if the substance acts as a catalyst.

Question 2: Identify two variables that should be controlled during an experiment testing the catalytic effect in forensic analysis and explain why.

Answer: Variables to control include temperature and concentration of reactants. Consistent temperature ensures that any change in reaction rate is due to the catalyst, and consistent reactant concentration ensures comparability between tests.

Question 3: List safety precautions that should be observed when working with chemical catalysts in a forensic laboratory.

Answer: Wear protective gloves, goggles, and lab coats; work in a well-ventilated area or fume hood; handle chemicals with care to avoid spills or inhalation; follow proper disposal procedures.

Question 1: In a forensic experiment, two samples containing a suspected catalyst were tested to break down a chemical compound. Sample A showed complete breakdown in 15 minutes, while Sample B took 2 hours. Explain how the presence of a catalyst influenced the reaction rate and what this implies about Sample A.

Answer: The presence of a catalyst in Sample A significantly increased the reaction rate, leading to faster breakdown. This suggests that Sample A contains an effective catalyst that lowers the activation energy, making the reaction proceed much quicker than in Sample B.

Question 1: Describe how catalysts are used in the production of automotive catalytic converters and explain how this relates to environmental protection.

Answer: Automotive catalytic converters use catalysts, such as platinum and palladium, to convert harmful gases like carbon monoxide, nitrogen oxides, and unburned hydrocarbons into less harmful substances like carbon dioxide, nitrogen, and water. This process reduces vehicle emissions, helping to protect the environment and improve air quality.

Question 2: Explain how forensic scientists might use catalysts to speed up chemical reactions when analyzing evidence from a crime scene.

Answer: Forensic scientists may add catalysts to reaction mixtures to accelerate the breakdown or detection of substances such as drugs, toxins, or residues. This speeds up analysis, allowing quicker identification of evidence and aiding timely investigations.