Verification of the Henderson-Hasselbalch Equation using Buffer Solutions, Lab Reports of Chemistry

Download Verification of the Henderson-Hasselbalch Equation using Buffer Solutions and more Lab Reports Chemistry in PDF only on Docsity! UNIVERSITI TUNKU ABDUL RAHMAN FACULTY OF SCIENCE BACHELOR OF SCIENCE (HONS) CHEMISTRY YEAR 1 TRIMESTER 1 UDEC1224 CHEMISTRY LABORATORY II Name of group members 1. Chan Yong Li (19ADB04214) 2. Foo Yu Cheng (18ADB02613) 3. Loo Xin Tong (19ADB02955) Practical Group P3 Practical Sub-group G3 No. of Experiment Experiment 4 Title of Experiment Verification of the Henderson-Hasselbalch Equation using Buffer Solutions Date of Experiment 15th July 2019 Date of Submission 22nd July 2019 Name of Lecturer Dr Ooi Mei Lee 1.0 Title Verification of the Henderson-Hasselbalch Equation using Buffer Solutions 2.0 Objectives 1. To study the validity of Henderson-Hasselbalch equation to a buffer system. 2. To determine the buffer capacity of a buffer system. 3.0 Results Initial pH of CH3COOH before adding with NaOH = 2.20 Volume of 1M CH3COOH (aq) (x) Volume of 1M NaOH (aq) (y) pH [SALT ] [ ACID ] = y (x− y) log10 [SALT ] [ ACID ] 50 1 2.87 1 50−1 =0.0204 -1.6902 50 2 3.15 2 50−2 =0.0417 -1.3802 50 3 3.45 3 50−3 =0.0638 -1.1950 50 4 3.53 4 50−4 =0.0870 -1.0607 50 5 3.63 5 50−5 =0.1111 -0.9542 50 10 4.01 10 50−10 =0.2500 -0.6021 50 15 4.01 15 50−15 =0.4286 -0.3680 50 20 4.35 20 50−20 =0.6667 -0.1761 50 25 4.53 25 50−25 =1.0000 0.0000 50 30 4.79 30 50−30 =1.5000 0.1761 50 35 5.03 35 50−35 =2.3333 0.3680 50 40 5.25 40 50−40 =4.0000 0.6021 50 45 5.70 45 50−45 =9.0000 0.9542 If a small amount of strong acid is added to the buffer solution, the strong acid will combine with an equivalent amount of the conjugate base and convert it to the weak acid form. Therefore, the concentration of the salt decreases while the concentration of the acid increases. However, the logarithm of the overall ratio does not change significantly. Similarly, if a small amount of strong base is added to the buffer solution, the concentration of the salt increases while the concentration of the acid decreases, but the logarithm of the overall ratio has only an insignificant change. The buffer capacity of the solution is the amount of acid or base that can be added without causing a significant change in pH. This property is determined by the relative concentrations of acid and salt in which the higher their concentrations, the higher the amount of acid or base the solution can accommodate before the relative acid/salt ratio is changed (OSU Chemistry REEL Program, n.d.). The buffer capacity of the acetic acid buffer system is 0.1012. 6.0 Precaution steps 1. Lab coat must be worn whenever one enters the laboratory to provide protection for the arms and the body from any harmful substances. 2. Lab goggles must be worn to prevent liquid splashes to eyes. 3. Glassware must always be handled carefully as glass tubing can easily be broken and can cause severe damage to hands. 7.0 Conclusion The Henderson-Hasselbalch equation is valid from pH of 2.87 to 6.42 and invalid from the pH of 6.42 to 12.08 in the acetic acid buffer system. The buffer capacity of the buffer system is 0.1012. 8.0 References UNC Eshelman School of Pharmacy, n.d. Buffers and Buffer Capacity. [online] Available at: <https://pharmlabs.unc.edu/labs/ophthalmics/buffers.htm> [Accessed 16 July 2019]. OSU Chemistry REEL Program, n.d. Buffer Capacity. [online] Available at: <https:// research.cbc.osu.edu/reel/research-modules/environmental-chemistry/methods/buffer-capacit y/> [Accessed 16 July 2019].