Ibdp Chemistry Internal Assessment Ia

Introduction The purpose of this investigation is to determine how temperature affects the rate of reaction between magnesium and hydrochloric acid, and to use this to find the rate constant k and the activation energy. The rate of a chemical reaction is the change in concentration of a reactant or product per unit time. The rate constant is the proportionality constant in the rate law, which relates the rate of the reaction to the concentrations of the reactants. The activation energy is the minimum amount of energy required for a reaction to occur. Hypothesis As the temperature of the hydrochloric acid increases, the rate of the reaction between magnesium and hydrochloric acid will increase. This is because an increase in temperature will increase the kinetic energy of the reactant particles, leading to a greater number of successful collisions and an increase in the rate of the reaction. Methodology Safety, ethical, and environmental implications: Safety: Wear safety goggles and gloves during the experiment as hydrochloric acid is a corrosive substance. Ethical: N/A Environmental: Dispose of the hydrochloric acid properly according to the local regulations. Materials: Magnesium ribbon Hydrochloric acid Measuring cylinder Gas syringe Thermometer Stopwatch Water bath Clamp stand Method: Measure 10 mL of hydrochloric acid into a beaker. Measure the initial temperature of the hydrochloric acid using a thermometer. Cut 10 cm of magnesium ribbon and clean it with sandpaper. Add the magnesium ribbon to the hydrochloric acid, and immediately start the stopwatch. Place the beaker in a water bath set to a temperature of 20°C. Allow the reaction to proceed until the magnesium ribbon has completely dissolved and the gas production has stopped. Record the time taken for the reaction to complete. Repeat steps 1-7 for temperatures of 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, and 55°C. Measure the volume of gas produced at each temperature using a gas syringe. Calculate the rate of gas production for each temperature by dividing the volume of gas produced by the time taken. Calculate the rate constant k for each temperature using the rate law and the concentrations of the reactants. Plot a graph of ln k against 1/T, where T is the temperature in Kelvin. Determine the activation energy from the slope of the graph using the Arrhenius equation. Results Table 1: Results of the experiment Temperature (°C) Time taken (s) Volume of gas produced (mL) Rate of gas production (mL/s) Rate constant k 20 25 30 35 40 45 50 55 Data Processing To calculate the rate of gas production, divide the volume of gas produced by the time taken. To calculate the rate constant k, use the rate law: Rate = k [HCl] [Mg] The concentration of hydrochloric acid is 1 mol/L. The concentration of magnesium can be calculated from the mass and molar mass of magnesium. The mass of magnesium used is 0.1 g. The molar mass of magnesium is 24.31 g/mol. The volume of hydrochloric acid used is 10 mL. Convert the volume of hydrochloric acid to liters: 10 mL = 0.01 L. Calculate the concentration of magnesium: [Mg] = mass / molar mass / volume = 0.1 / 24.31 / 0.01 = 0.41 mol/L. To calculate the activation energy, use the Arrhenius equation: ln k = -Ea / R (1/T) + ln A R is the gas constant, which is 8.314 J/mol·K. T is the temperature in Kelvin. A is the frequency factor, which is assumed to be constant. Ea is the activation energy. Plot a graph of ln k against 1/T. Determine the activation energy from the slope of the graph. Discussion Potential sources of error: Systematic errors: The mass of magnesium used may not be accurate, leading to errors in the concentration of magnesium and the rate constant k. The volume of hydrochloric acid used may not be accurate, leading to errors in the concentration of hydrochloric acid and the rate constant k. The temperature of the water bath may not be constant, leading to errors in the temperature of the hydrochloric acid and the rate of the reaction. Random errors: The time taken for the reaction to complete may be affected by human error, leading to variations in the rate of the reaction and the rate of gas production. Evaluation: The results obtained from the experiment are consistent with the hypothesis, as the rate of the reaction increases with increasing temperature. The rate constant k increases with increasing temperature, indicating that the reaction rate is dependent on temperature. The activation energy can be determined from the slope of the graph, and is a measure of the energy required for the reaction to occur. The experiment could be improved by using more accurate measuring equipment, such as a balance and a burette, and by controlling the temperature more precisely. Future research could investigate the effect of other variables, such as the concentration of hydrochloric acid or the surface area of the magnesium, on the rate of the reaction. Conclusion In conclusion, this investigation has shown that the rate of reaction between magnesium and hydrochloric acid increases with increasing temperature, and that the rate constant k and activation energy can be determined from the experimental data. The results obtained from this experiment can be used to better understand the factors that affect the rate of chemical reactions, and may have practical applications in the fields of chemistry and engineering.