Determinationofreactionorder

Determinationofreactionorder

Determination of Reaction Order ⇔ AP Chemistry Lab
Introduction: In this experiment you will measure the time required for magnesium to react with hydrochloric acid of various concentrations. From this data you will calculate the rate of reaction for each experiment and graphically determine the order of reaction with respect to the hydrogen ion concentration. Magnesium ribbon will be cut into six equal pieces. Since the ribbon is fairly uniform in manufacture, the length is proportional to the surface area, and the area for reaction is very nearly the same for each piece. We can assume that the concentration of Mg is the same for each trial and that variations in rate are attributes to variations in acid concentrations. Six, 24 mL aliquots (portions) of HCl, having varying molarities, will be used. These aliquots will prepared by diluting portions of a 6.0 M stock solution. Amounts of 6.0 M HCl used will be calculated according to the equation M1V1=M2V2. For this reaction, the net ionic equitation is Mg + 2H+(aq) → H2 (g) + Mg2+. The general rate equation is rate= k[H+]n where “n” is the order of the reaction and the rate can be expressed in terms of reciprocal time, i.e. rate=1/t. Taking the natural log of both sides of the equation gives ln(1/t) = n(ln[H+]) + ln(k). This has the form of a linear equation y = mx+b. where the slope is the order (n) and the y-intercept is the natural log of the rate constant, k. Objectives: 1. Separation of solutions of hydrochloric acid in concentrations of 0.5M, 1.0M, 2.0M, 3.0M, 4.0M, 5.0M. 2. Reaction of measured amounts of magnesium metal with each of the portions of HCl, with measurement of time necessary for reaction to be complete. 3. Graphing of data and calculation of rate constant, k. Safety precautions: HCl is a strong acid and present in this lab in high concentration. Be careful to avoid skin contact as well as clothing contact. Wear safety goggles and an apron for this experiment. Equipment: Test tubes or...