H2P04-(aq) H+(aq) + HP042-(aq) For this system, you will rely on pH measurements
ID: 590604 • Letter: H
Question
H2P04-(aq) H+(aq) + HP042-(aq) For this system, you will rely on pH measurements using the universal indicator paper found in your locker. The pH indicates the H' concentration in solution. Relative to pure water, acidic solutions have a higher [H+] and a pH 7. For each solution, record the color of the indicator paper and the approximate pH. 1. Place about 2 mL of the H,Po4/HPO2 buffer solution in a clean, small test-tube. Determine the pH of this solution. 2. Determine the pH of 1 M HCI by placing one drop on a new piece of indicator paper. 3. Add one drop of 1 M HCI to the buffer solution, mix well, and determine the phH 4. Place about 2 mL of distilled water in a clean, small test tube. Determine the pH of the water 5. Add one drop of 1 M HCI to the water, mix well, and determine the pH. 6. Compare the pH of the buffer to that of the distilled water before adding HCl. Then compare the pH after adding HCl. Explain why the buffer had a significantly different response to added H ions than did the water.Explanation / Answer
HCl is a strong acid, Adding of HCL means addition of H+ ions. Due to the addition of H+ ions the above equilibrium will changed as per La chatelier principle. The equilibrium will shifted to left side mean mole of salt is decrease and the mole of weak acid increases. Also, the total volume of the solution is changed. so, mole number of salt and acid including volume is changed, Therefore, concentration will be also changed. According to Henderson equation to determine the pH of buffer solution,
pH = Pka + log {[salt]/[acid]}
pH will be changed significantly due to addition of HCl.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.