Purpose Titration is a technique where an unknown solution’s concentration is determined with a solution of a known concentration. In this case, the known solution, NaOH, is dripped into the unknown, unknown #2, with a burette. The NaOH is dripped until the reaction is complete, while measuring the pH per amount of base added. Using the data collected, the equivalence point can be found and the concentration can be calculated. Then the KA can be found at specific points (20%, 40%, etc). After finding the KA’s at specific points the average can be taken and compared with actual KA to determine the identity. Another method used was qualitative methods. 3 indicators were set up with specific ranges of pH for colour change. Each of the indicators
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5 drops of thymol blue, malachite and, crystal violet were added to separate test tubes filled with 5mL of unknown #2. The colour change was observed and compared with the tubes with the acetic acid and its chloro- derivatives with the separate indicators. The identity of the unknown acid was recorded. Then, the pH meter was calibrated with 3 standardized buffer solutions at pH 4, pH 7, and pH 10. Then, 25mL of the unknown acid was added to a 100ml beaker and placed under the burette. The magnetic stirring bar was added and the pH meter’s bulb was placed into the beaker to measure the pH. The first 3ml were added in intervals of 0.1mL and 0.5mL, then at 1mL increments until the pH began to rise noticeably then at 1 drop increments. After the equivalence point 1mL was added until reached 45mL of base added. All while recording pH and burette reading after each addition …show more content…
Because there are 5 things simultaneously present, 5 equations must be made. Two for the equilibrium constants, one mass balance equation for all A containing material and one for Na+, and 1 charge balancing equation as shown in the appendix. Since we are looking for the KA we need the equation in the form of KA = [H3O+][A-]/[HA]. Therefore the 5 equations must be rearranged to fit the equation. Once the equations are rearrange and put into the KA equation then the KA at different points can be calculated. You must calculate the KA at multiple points because the data one collects won`t always be correct and it’s safer to acquire and average to safely call that the KA value because some points on your graphs may be outliers. To calculate the average KA all of the KA`s at specific points are added together and divided by how many points there were. The KA was calculated to be 2.37×10-5 excluding the KA`s at 60% and 100% due to the them being different by an order of magnitude, this would cause the results to veer from one side to another. Comparing with the KA of acetic acid online 1.75 ×10-5 [2] the percentage error was calculated and was 35%. Therefore with the acid is acetic acid. Some experimental errors within this experiment are mostly human errors such as not having the previous group properly clean the test tubes. This causes there to be some residue left over from the
5 drops of thymol blue, malachite and, crystal violet were added to separate test tubes filled with 5mL of unknown #2. The colour change was observed and compared with the tubes with the acetic acid and its chloro- derivatives with the separate indicators. The identity of the unknown acid was recorded. Then, the pH meter was calibrated with 3 standardized buffer solutions at pH 4, pH 7, and pH 10. Then, 25mL of the unknown acid was added to a 100ml beaker and placed under the burette. The magnetic stirring bar was added and the pH meter’s bulb was placed into the beaker to measure the pH. The first 3ml were added in intervals of 0.1mL and 0.5mL, then at 1mL increments until the pH began to rise noticeably then at 1 drop increments. After the equivalence point 1mL was added until reached 45mL of base added. All while recording pH and burette reading after each addition …show more content…
Because there are 5 things simultaneously present, 5 equations must be made. Two for the equilibrium constants, one mass balance equation for all A containing material and one for Na+, and 1 charge balancing equation as shown in the appendix. Since we are looking for the KA we need the equation in the form of KA = [H3O+][A-]/[HA]. Therefore the 5 equations must be rearranged to fit the equation. Once the equations are rearrange and put into the KA equation then the KA at different points can be calculated. You must calculate the KA at multiple points because the data one collects won`t always be correct and it’s safer to acquire and average to safely call that the KA value because some points on your graphs may be outliers. To calculate the average KA all of the KA`s at specific points are added together and divided by how many points there were. The KA was calculated to be 2.37×10-5 excluding the KA`s at 60% and 100% due to the them being different by an order of magnitude, this would cause the results to veer from one side to another. Comparing with the KA of acetic acid online 1.75 ×10-5 [2] the percentage error was calculated and was 35%. Therefore with the acid is acetic acid. Some experimental errors within this experiment are mostly human errors such as not having the previous group properly clean the test tubes. This causes there to be some residue left over from the